EP1021766A1 - Itinerary based agent mobility including mobility of executable code - Google Patents

Abstract

In accordance with the present invention, a mobile agent object (10) executes a first method (18) on a first computer (12), migrates from the first computer (12) to a second computer (14), and executes a second method (20) on the second computer (14). The first and second methods and first and second computers are designated in an itinerary (28). The agent includes both data (22) and executable code (24, 26) which are serialized for transmission from the first computer to the second computer as data. The data containing the agent is then deserialized in the second computer to regenerate the agent in the form of an object. The executable code portion of the agent can be supplemented with code from a home codebase located on another computer.

Description

TITLE OF THE INVENTION ITINERARY BASED AGENT MOBILITY INCLUDING MOBILITY OF EXECUTABLE CODE

CROSS REFERENCE TO RELATED APPLICATIONS A claim of priority is made to U.S. provisional patent application Serial Number 60/030,906, entitled USE AND COLLABORATION OF MOBILE AGENTS IN A COMPUTER NETWORK, filed

November 14, 1996.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

BACKGROUND OF THE INVENTION The present invention is generally related to network computing, and more particularly to mobile objects.

Mobile objects that are transmitted across a computer network are known. Mobile objects are comprised of code and data, both of which are transmitted across the computer network. Technologies such as client-server protocols, remote procedure call protocols, and distributed object technologies are employed to transmit mobile objects across the computer network. These technologies implement either a "push" model or a "pull" model, both of which have drawbacks.

In a "pull" model the code for an executing object iε downloaded from a network source such as a web server. When a particular portion of code becomes necessary for operation, that portion of code is first sought on the local filesystem. If the local filesystem does not include that portion, of the code, a network request is sent to another computer in the network in order to prompt transmission of that portion of code to the local computer. However, as different classes of sub-objects are created, a separate network request must be sent to retrieve code for each class . In the case of a Hyper-Text Transfer Protocol ("HTTP") request, each request must re-establish a Transmission Control Protocol/Internet Protocol ("TCP/IP") socket connection to the web server. Thus, when downloading a large number of classes, a large number of connections must be established and a large amount of network overhead is incurred.

Another drawback associated with the pull model is that as an object travels, the code which enables the object to operate must be re-downloaded at each computer. More particularly, when the object arrives at each a destination computer, the object downloads any code which is required but not present on the local filesystem, even if that code was downloaded at the previous destination computer. Previously downloaded code is not cached. Network overhead is incurred as a consequence.

In a "push" model the code for an executing object is carried with the mobile object. Prior to launching the mobile object, all of the code that will be needed by the object is identified. The code is packaged with the agent and pushed around the network to each destination computer. While the push model reduces network requests in comparison with the pull model, network overhead is still incurred because of the relatively large amount of code that is pushed to every destination computer. In some cases the object will push code for classes that are no longer needed. For example, an agent may create an instance of a particular class of object only in very exceptional circumstances. In such a case it is inefficient for the object to push the code for this class.

Another limitation of known mobile objects is difficulty in examining and predicting destination information. Known mobile objects initiate travel by performing a subroutine call. The method is sometimes given a name such as "go" or "moveTo," and the caller is responsible for specifying a name or Uniform Resource Locator ("URL") indicating the destination computer for the mobile object. When the travel method is called, the execution of the mobile object is halted and the mobile object is converted into a network transmittable form. On the destination computer the mobile object is restored from the network form and restarted. This restart can either occur on the instruction directly following the call to the travel method, or at the beginning of some known method.

BRIEF SUMMARY OF THE INVENTION In order to provide efficient mobility of code for a mobile agent object ("agent"), a "mobile codebase" object is constructed. The mobile codebase travels with the agent and serves as a repository of code for classes that facilitate agent operation. When the agent is launched, the launcher specifies a list of related classes. These classes are retained in the mobile codebase. The launcher also specifies a Uniform Resource Locator ("URL") that points to a network source ("home codebase") from which code can be downloaded.

If the agent is required to instantiate an object comprising code that is not in the mobile codebase, a network request is sent to the home codebase to retrieve that code. Code that is downloaded in this manner is retained in the mobile codebase .

The combination of the mobile codebase and home codebase improve agent operation and reduce network overhead. In a preferred embodiment an agent is launched with a mobile codebase that is preloaded with classes which are certain to be needed. Classes that are unlikely to be needed are stored in the home codebase. Thus the agent with mobile codebase and home codebase provide the desirable features of the push and pull models without the undesirable network overhead incurred by transmitting unneeded classes around the network or re-downloading code.

Agent travels are defined by an itinerary data structure. The itinerary is composed of a list of destinations, each of which includes: (1) the hostname of a destination computer on the network to which the agent should travel, and (2) the name of a method that the agent should execute when the agent arrives at the destination computer. An agent is allowed to modify its itinerary. When an agent modifies its itinerary, the agent owner is automatically notified, thus allowing the owner to "follow" the agent wherever it may travel .

The itinerary provides advantages related to agent and network management. Inspection of the agent itinerary reveals where the agent has travelled and where the agent may travel in the future. Since the itinerary is a standard data structure, an observer can depend on it to be present. Further, since the itinerary is a separate data structure from the agent, the observer does not need special knowledge of the internal structure of the agent in order to examine the itinerary.

BRIEF DESCRIPTION OF THE DRAWING The invention will be more fully understood from the following Detailed Description of the Invention, in conjunction with the Drawing, of which:

Fig. 1 is a block diagram which illustrates agent migration;

Fig. 2 is a block diagram which illustrates agent execution in conjunction with agent migration; Fig. 3 is a block diagram of an agent;

Fig. 4 is a block diagram of agent interaction with agent managers on multiple computers in a network;

Fig. 5 is a flow chart which illustrates agent mobility; Fig. 6 is a block diagram which illustrates agent operation according to an itinerary;

Fig. 7 is a block diagram which illustrates the agent runtime environment; and

Fig. 8 is a flow chart which illustrates agent deserialization.

DETAILED DESCRIPTION OF THE INVENTION Referring to Fig. 1, an agent 10 comprises a mobile object which can travel from a first computer 12 to a second computer 14 in a computer network 16. The agent is generated and stored in memory on the first computer for a specific purpose, and includes both data and executable code. The agent executes on the first computer and then migrates to the second computer by being transmitted across the network. The agent then resumes execution on the second computer. When the agent completes execution on the second computer, the agent acts in accordance with an agent itinerary. For example, the agent will migrate to another computer if the itinerary so indicates.

Referring now to Figs. 1 and 2, the agent executes a sequence of instructions during operation. In particular, a first method 18 is executed on the first computer 12 and a second method 20 is executed on the second computer 14. As a result, migration between computers is transparent from the perspective of the agent .

Referring to Fig. 4, agent mobility is preferably facilitated through use of JAVA agent manager Objects 32 and an Object Serialization facility (a product of Sun Microsystems which is known in the art) . Object Serialization operates to serialize objects such that a representative stream of bytes, i.e., data, is generated therefrom. Object Serialization facilitates transmission of an agent across the network by serializing the agent 10 into a format that is suitable for network transmission. Serialization of the agent may also include serialization of sub-objects which are contained within member variables of the agent. In accordance with the present invention, the serialization process involves the serialization of executable code, data, and an itinerary as hereinafter discussed in greater detail. Once the agent has been serialized, a communication socket to the second computer is opened and the resulting stream of bytes is transmitted to the second computer along the socket.

The serialized agent is regenerated in the second computer 14 upon arrival. In particular, the stream of bytes transmitted along the socket is deserialized in the second computer. Deserialization regenerates the agent in the form in which the agent existed prior to migration, i.e., an object. Following deserialization, the agent executes a predetermined method specified by its itinerary. The predetermined method may prompt interaction with another object 34 located on the second computer. When the method has been executed, the agent is serialized and transmitted to yet another computer, or possibly back to the first computer. The agent is therein deserialized upon arrival and proceeds to execute another predetermined method and interact with that computer. In the case of the agent migrating back to the first computer, such interaction could be with a host application 36 through which an information query was entered. The agent continues migrating across the network in this manner as execution requires. Eventually, the agent is terminated when execution of the itinerary is complete. It should be noted that the agent need not necessarily migrate to the initial host (first) computer after executing on a remote (second) computer. The agent could travel to multiple computers, and may not return to the initial host computer.

Referring to Fig. 3, each agent may include data 22, code 24, sub-objects 26 and an itinerary 28. The data portion 22 includes internal state information associated with the agent. The code portion 24 includes executable code associated with operation of the agent. The itinerary portion 28 specifies destinations for the agent. Sub-objects 26 include code of distinct objects contained within the agent. The agent carries the code for these sub-objects. The code 24 portion of the agent 10 includes a mobile codebase and a reference pointer to a home codebase. The mobile codebase comprises executable code which is retained as part of the agent. When the agent migrates, the mobile codebase is transmitted along with the data, sub-objects and itinerary to the destination. The home codebase is executable code which resides on the computer which originally created and launched the agent or a suitable network server (such as a web server) . The reference pointer to the home codebase is a Uniform Resource Locator ("URL") that allows remote access to the home codebase from other computers in the network. If the agent requires code that is not present in the mobile codebase during execution, the agent retrieves the required code from the home codebase and retains such retrieved code in the mobile codebase.

Referring to Figs. 3 and 6, the itinerary 28 is a data structure which defines agent migration parameters. The itinerary is composed of a list of destinations and the name of a method associated with each such destination. In a preferred embodiment, each destination entry contains the Transmission Control Protocol/Internet Protocol ("TCP/IP") host name of a computer on the network to which the agent is designated to migrate. The method associated with the respective destination is invoked upon arrival at that destination. Hence, each destination represents a location and a task to be performed at the location.

Figs. 4 and 5 illustrate agent mobility. When the determination is made that the agent should migrate, the agent manager 30 examines the itinerary 28 to ascertain the next destination to which the agent 10 is designated to migrate. The agent manager 30 establishes a network connection to the agent manager 32 at the destination computer 14. The agent manager 30 passes the agent and related travel information to the destination agent manager

32. The agent manager 30 then deletes the local copy of the agent, terminates any execution threads which were being used by the agent, and performs other appropriate clean up activities . From the perspective of the destination computer, the agent arrives at the destination computer as illustrated in step 38. As previously described, the agent arrives in the form of data which includes the code, sub-objects, itinerary and other data. Java/Object Serialization assists the de- serialization and reconstruction of the agent as depicted in step 40. The server then spawns a new thread in which the agent will execute as shown in step 42. A persistent local copy of the agent is then made as illustrated in step 44. As depicted in step 46 the agent manager invokes the proper method of the agent for execution in the spawned thread at this node. The itinerary contains information indicating which method should be invoked at each designated destination computer. The agent then executes as illustrated in step 50. When the agent has completed execution of the indicated method, another persistent copy of the agent is stored on the local disk as depicted in step 52 in order to prevent redundant execution in the event that the computer malfunctions before the agent migrates. The agent manager then examines the agent itinerary as illustrated in decision step 54. If the itinerary does not indicate any further destinations then agent execution is deemed complete as shown in step 56. However, if the itinerary indicates further destinations, then the agent manager determines whether the next destination is associated with another computer in decision step 58. If the next destination is not another computer, flow returns to step 44, thereby bypassing network traffic. However, if the next destination is associated with a different agent manager then a network connection to the indicated agent manager is established as depicted in step 60. The destination contains a string which indicates where to travel. The string contains either the name (host name) of a computer or a URL to a distributed object. The agent is then serialized as illustrated in Step 62 and subsequently transmitted to the next agent manager as depicted in Step 64.

Migration in accordance with the itinerary 28 is further illustrated in Fig. 6. The itinerary includes a listing including identification of each agent manager 66 to which the agent is configured to migrate and identification of a method 68 to execute at each respective agent manager. The agent migrates through the agent managers listed in the itinerary sequentially in the order in which the servers are listed, invoking each respective method upon arrival. Such method could be, for example, querying or updating a database on the destination computer.

Fig. 7 illustrates the agent runtime environment. Each computer 70 on the network includes a Java Virtual Machine 72 running therein. A agent manager 74 runs on each respective Virtual Machine 72. The agent manager includes a plurality of threads 76, each thread having an agent 78 associated therewith. In particular, a new thread is formed when a new agent arrives at the server, and the agent executes on that thread. Security mechanisms prevent each agent from operating outside the scope of the associated thread. When agent execution completes, the agent migrates to the next destination identified in the itinerary.

In order for migration and execution to function properly, the agent manager modifies the mechanism by which Java loads classes. The Java standard library provides an object called a "ClassLoader" which can be subclassed by a programmer to modify the rules that Java follows to load classes. The ClassLoader class allows web browsers to download "applets" from a web server. The agent manager provides a specialized ClassLoader which allows the executable code for mobile agents to travel with the agent. During a typical execution of a Java program, a Java interpreter loads classes as needed for execution from a logical file system on the local computer. However, agents become separated from the home computer and the home codebase during migration, i.e., agents are separated from the directory or directories on the filesystem of the home computer where the code is stored. Further, sub-objects sometimes need to be created as the agent executes, either as member variables or as temporary variables within the methods. These sub-objects could be instances of classes which are part of the standard Java packages or they could be instances of new classes written by the programmer of the agent. However, since the agent is executing on a different computer than the home computer following migration, the Java virtual machine may not be able to directly retrieve the code for the particular sub-object. To allow agents to properly load classes and construct objects when remote from the home computer, a special ClassLoader is employed by the agent manager whenever an agent attempts to construct an object. The ClassLoader object first attempts to locate a class on the local file system of the computer. If the class is not on the local file system, the ClassLoader searches the mobile codebase. If such attempt fails, the ClassLoader sends a request back to the home machine of the agent. The agent's travel information contains a reference such as a URL which refers back to the home codebase on the home computer, and by accessing the URL the ClassLoader can retrieve classes from the home computer. Agent deserialization is illustrated in Fig. 8. As depicted in step 80 the serialized agent arrives as a stream of data. Java Development Kit Object Serialization classes then call an agent manager related method to perform deserialization as shown in step 82. The method reads agent related objects from the object stream as depicted in step

84. In particular, the mobile codebase, itinerary and codebase URL are read by the method. A custom Classloader and ObjectInputStream are constructed as shown in step 86. Object Serialization then reads the agent and other objects from the input stream as depicted in step 88 and step 90, respectively. When the related objects are read, the ClassLoader retrieves the classes which comprise the agent as illustrated in step 92.

The new object's class is loaded once the classes are retrieved. As depicted in step 94, if the class is determined to have been previously loaded then the previously loaded class instance is employed (step 96) and the object is instantiated using the loaded class object as shown in step 98. However, if the class has not been previously loaded as determined in inquiry step 94, then inquiry is made as to whether the class is on the local class path of the destination computer as illustrated in decision step 100. If the class is present on the local machine then the class is loaded therefrom as shown in step 102 and the object is instantiated using the loaded class object as depicted in step 98. However, if the class is not found on a local class path as shown in step 100 then an inquiry is made as to whether the class is in the mobile codebase as shown in step 104. If the class is located in the mobile codebase then the class is loaded therefrom as shown in step 106 and the object is instantiated using the loaded class object as shown in step 98. However, if the class is not located in the mobile codebase in decision step 104 then the class is loaded by accessing the home codebase as shown in step 108. If the codebase pointer is an Internet type pointer such as a Hyper- Text Transfer Protocol ("HTTP") URL, as determined in inquiry step 110, then an HTTP request is sent to the local web server as shown in step 112 and the retrieved class is added to the Mobile CodeBase as depicted in step 114. However, if the codebase URL is not a HTTP URL then a remote method request is sent to a RemoteClassLoader object as shown in step 116 and the class is added to the mobile codebase as shown in step 114. In either case, the object is instantiated using the loaded class object as shown in step 98. If more objects exist in the stream to be retrieved, as determined in decision step 118, then another object is read from the input stream as illustrated in step 90. If there are no more objects to be retrieved, flow terminates.

Having described the preferred embodiments of the invention, other embodiments which incorporate concepts of the invention will now become apparent to one of skill in the art. Therefore, the invention should not be viewed as limited to the disclosed embodiments but rather should be viewed as limited only by the spirit and scope of the appended claims .

Λ program listing follows in the attached APPENDIX. Agent. java_l Tue Nov 12 08:01:22 1996 1

1 /* $Header: /com/mei ca/hsl/zones j gents /shared/Agent . Java 13 9/30/9

2

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology America.

5 * All rights reserved. 6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Base class for mobile Agent

11 *

12 * $Log : /com/meitca/hsl/zonesjagents/shared/Agent . Java $

13 *

14 * 13 9/30/96 6:23Ό Walsh

15 * clean up javadoc comments

16 * . 17 * 12 9/29/96 4:09p Walsh

18 * Give Agent access to Agen Package information 19

20 * 11 9/28/96 6:Ξ7p Walsh

21 * Comment out debug println

22

23 * 10 9/09/96 4 : 53p Walsh

24 * Add prepareForTransporc , completedTransport methods 25

26 * 9 9/04/96 3:18p Noemi

27 * Added static initializer. Moved functionality related to collaborat

28 * to new CollaboratorAgent subclass. 29

30 * 8 8/30/96 4:30p Noemi

31 * Changed constructors and_ finalizer to operate on AgentGroup referenc

32 * (rather than AgentGroupIm 1 references) .

33 *

34 * 7 8/28/96 2:45p Noemi 35 * Removed SourceSafe conflict garbage.

36

37 * 6 8/28/96 2:20p Noemi

38 * Added support for AgentGroups .

39 *

40 * 5 8/23/96 3:52p Walsh

41 * Remove live method (superceded by ad-hoc invocation)

42 *

43 * 4 8/22/96 6 : 36p Walsh

44 * Remove parameter to live method

45 *

46 * 3 8/13/96 2:23p Walsh

47 * Add some comments & documentation

Agent. ava_l Tue Nov 12 08:01:22 1996 2

48 *

49 * 2 8/09/96 4:49p Walsh

50 */

51 package com. meitca. hsl . zonesjagents . shared;

53 import Jav .util . *;

54 import Java .net . InetAddress ; 55

56 import com. meitca .hsl . zones;agents . conduit . * ;

57

58

59 /**

60 * A base class representing a traveling agent program. All user defined

61 * agents should be derived from the class Agent. An agent

62 * travels from machine to machine as dictated by its Itinerary. At each stop,

63 * a specified method will be invoked. After the method completes, the Agent

64 * will be sent tc the next host on the itinerary. To develop an agent, a

65 * programmer should derive a class from Agent.

66 * @see ConcuitServer

67 * Ssee AgentGroup

68 * Sauthor Noemi Paciorek 69 * ©author Thoiras Walsh

70 */

71 public abstract class Agent { 72

73 // Class variables

74 /** A counter used to generate the Agent's ID /

75 protected static ir.t agentNu = 0; // counter for agents started on a system 76

77 /** A unique ID representing the host the agent was initiated from*/

78 protected static String host; // unique host ID 79

80 // Instance variables

81 /** A un_gue ID representing the Agent */

82 protected String agent ID; // unique agent ID

83

84 // A reference to the Agent's AgentPackage. This reference will only be

85 // valid when the Agent is actually tavelling. Prior to travel, this

86 // will be a null reference (for example the reference will be null

87 // when the Agents constructor is executing) .

88 private AcentPackage itsPackage;

89

90 // Static initializer

91 static {

92 /*

93 * Try to obtain the host's name and IP address. If this fails,

94 * construct a pseudo-random name and hope for the best! (Of course,

Agent. java_l Tue Nov 12 08:01:22 1996 3

95 * this should never happen.)

96 */

97 try {

98 host = Iπet÷Address .getLocalHost () .toString () ;

99 } catch (Exception e) {

100 hose = " FOSTID " + new Random( ) .nextLong ( ) ;

101 }

102 } ^* 103

104 // Constructors

105 /** Constructs an Agent */

106 public Agent () {

107 /*

108 * Assign a unique agent ID.

109 */

110 try {

111 agentID = host + "/agent" + nextAgentNum( ) ;

112 //System. out. rintln( "Agent ID = " + agentID) ;

113 } catch (Exception e) {

114 System. out .println ( "Agent constructor error: " + e .getMessage ( )

115 e .printStackTrac ( ) ; 116

117 }

118

119 itsPackage = null;

120 } V 121

122 // Class methods

123 private final synchronized int nextAgentNum( ) {

124 return ++agentNum;

125 } 126

127 // Instance methods

128 /**

129 * Retrieves the Agents ' s ID. An AgentID is a unique String

130 * which identifies a particular instance of an Agent.

131 * δreturπ The Agent's ID.

132 */

133 public final String getAgentlDO {

134 return agentID;

135 }

136

137 / **

138 * Converts an Agent to a String. Implementation simply

139 * returns the AgentID.

140 * Sreturn A String representation of the Agent.

Agent. java_l Tue Nov 12 08:01:22 1996

142 public final String toStringO {

143 return geύAgentID( ) ;

144 } 145

146 /**

147 * This is called by the ConduitServer immediatley prior to

148 * the agent being transported to its next destination. Derived

149 * Agents can override this method to perform any final processing

150 * needed before transport

151 */

152 public void prepareForTransport ( ) {

153 } 154

155 /**

156 * This is called by the ConduitServer when the Agent arrives at

157 * its new destination. Derived Agents can override this method

158 * to perform any processing needed on arrival

159 */

160 publ ic void completedTransport ( ) {

161 }

162

163 /**

164 * Returns a reference to the Agents Itinerary. The Itinerary

165 * iε only available when the Agent is traveling. It is not

166 * available during -he Agent's constructor. If the Itinerary

167 * is not available, this method returns null.

168 * øreturr. The Agents Itinerary or null if the itinerary is

169 * not available

170 */

171 public Itinerary getltinerary ( ) {

172 if (izsPackage != null) {

173 return itsPackage .getltinerary () ;

174 } else {

175 return null;

176 }

177 }

178 179

180 * Returns a URL pointing to the Agent's codebase on it home machine.

181 * This URL is used in conjunction with the AgentCodebase class to

182 * retrieve the byteccdes of the Agent and it related classes.

183 * The URL available v;hen the Agent is traveling. It is not

184 * available during the Agent's constructor. If the URL

185 * is not available, this method returns null.

186 * ©return The URL of the Agents codebase or null if the URL is

187 * not available

188 */

Agent. java_l ue Nov 12 08:01:22 1996 5

189 public String getHomeCodebaseURL ( ) {

190 if (itsPackage != null) {

191 return itsPackage .getHomeCodebaseURL) ) ;

192 } else {

193 return null;

194 }

195 } 196

197 /**

198 * This Method is called internally by the ConduitServer to

199 * provide the Agencs with a reference to its package.

200 */

201 public void setPackage (AgentPackage agentPackage) {

202 itsPackage = agentPackage;

203 } 204

205 }

AgentCodebase. java_l Tue Nov 12 08:01:22 1996 1

1 /* $Header: /com/meitca/hsl/zonesjagents/εhared/AgentCodebase . ava 3 11/11/96 5:25p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Class providing accessability to the home codebase of the agent

11 *

12 * $Log : /com/meitca/hsl/ zonesjagents/shared/AgentCodebase . Java $

13 *

14 * 3 11/11/96 5:25p Billp

15 * Made correction to company name

16 *

17 * 2 9/30/96 6:23p Walsh

18 * clean up javadoc comments

19 *

20 * 1 9/28/96 6:35p Walsh

21 * intial version

22 3 */

24 package com.meitca .hsl . zonesjagents . shared;

25

26 import java.net.*;

27 import java.io.*

28 import sun . net . www.MeteredStream; 29

30 import com. meitca .hsl . zonesjagents . remoteloader .* ; 31

32 /**

33 * The AgentCodebase class provides accessability to the "home

34 * codebase" of an agent. As an agent travleε, it may construct

35 * an object whose bytecodes may not be installed on the machine

36 * to which it has travelled. In some cases, the agent may have

37 * already constructed another instance of the same class or, the

38 * user or programmer may have specified that this class was a 39 * "related class" when launching the agent. In both of these

40 * cases, the bytecodes for the class should have already been

41 * loaded into the Agent's MobileCodebase . If the bytecodes for

42 * the new object HAVE NOT already been loaded into the MobileCodebase,

43 * the ConduitServer needs a mechanism for finding an retrieving

44 * these bytecodes . The AgentCodebase provides an mechanism through

45 * which Agents can retrieve code from their home locations.

46 * Ssee Agent

47 * @see MobileCodebase

AgentCodebase . j va_l Tue Nov 12 98:01:22 1996

54 * agents codebase.

55 */

56 static final int UNKNOWN = -1;

57 static final int RMI = 0;

58 static final int HTTP = 1;

59 static final int FILE = 2; 60

61 /**

62 * The protocol to use to retrieve bytecodes from the

63 * AgentCodebase

64 */

65 int itsProtocol; 66

67 /** An URL pointing back to the AgentCodebase */

68 String itsURL;

69

70 /**

71 * A ClassFileLoader ooject which may be used to

72 * retrieve agent bycecod- 3 from the local filesystem

73 * (when a file: url s used to identify the codebase

74 */

75 ClassFileLoader itsClc.εsFileLoader ; 76

77 /**

78 * Constructs an AgentCodebase from the given URL.

79 * Oparan url An URL pointing to the AgentCodebase. This

80 * URL can be;<br>

81 * <ul>

82 * <li>An HTTP url pointing to a location on a web server

83 * (such as <b>http : //host/directory</b>)

84 * <li>An RMI url pointing to a RemoteClassLoader

85 * server (such as <b>rmi : //host/RemoteClassLoader/directory<

86 * <li>A FILE url pointing to a local directory

87 * (such aε <b>file :C : \directory</b>)

88 * <li>An empty string or null which indicates that the agents code

89 * is on the CLASSPATH of this machine.

90 * </ul>

91 * Sexception Malf or edURLException I f the url passed in was invalid

92 */

93 public AgentCodebase (String url) throws MalformedURLException {

94 itsProtocol = -1;

AgentCodebase. java_l Tue Nov 12 08:01:22 1996

95 itsURL = null;

96 itsClaεsFileLoader= null;

97 parseURL (url ) ; 98

99 if (itsProtocol == FILE)

100 itsClassFileLoader = new ClassFileLoader () ;

101 } 102

103 /**

104 * Retrieve the bytecodes for the given class

105 * @param classname The name of the class whose bytecodes to

106 * retrieve

107 * Sreturn The classes bytecodes in the form of a byte array

108 * ©exception ClassNotFoundException If the class could not be loaded

109 */

110 public byte [ ] retrieveCode(String classname) throws ClassNotFoundException {

111 switch (itsProtocol) {

112 case RMI:

113 return RemoteClassLoaderlmpl . retrieveRemoteClass (itsURL, classname);

114 case HTTP:

115 return retrieveHTTPClass (classname) ;

116 case FILE:

117 return itsClassFileLoader . loadClassFileFromDirectory (itsURL, classname);

118 default:

119 throw new ClassNotFoundException ( "Unsupported protocol");

120 }

121 } 122

123 /* Used internally to parse URL passes into ctor */

124 private void parεeUR (String url) throws MalformedURLException {

125 if (url '= null) {

126 int sep = url . indexOf ( ' : ' ) ; 127

128 if (sep != -1) {

129 String protocol = url . substring (0 , sep);

130 if (protocol .equals ( "rmi" ) ) {

131 itsProtocol = RMI;

132 itsURL = url;

133 } elεe if (protocol .equalε ( "http" ) ) {

134 itεProtocol = HTTP;

135 itsURL = url; 136 if ( itsURL. endsWith ( " / " ) ) {

137 itsURL = itεURL.εubεtring(0, itεURL. length { ) -1) ;

138 )

139 } elεe if (protocol . equals {" file" ) ) {

140 itεProtocol = FILE; 141

AgentCodebase.java_l Tue Nov 12 38:01:22 1996 4

142 // strip off the file: portion so all we are left with is

143 // the directory spec of the codebase.

144 itsURL = url . substring (sep+1, url . length ()) ;

145

146 } else {

147 // we will assume file since the user might be trying to specify a

148 // DOS style filename (ie C:\WINNT)

149 itsProtocol = FILE;

150 itsURL = url;

151 }

152 } else {

153 // assume file

154 itsProtocol = FILE;

155 itsURL = url;

156 }

157 } else {

158 // the URL was null. This means that the Agents code iε located somewhere on

159 // the class path of this machine. We will set the protocol to FILE and leave

160 // the url as null

161 itsProtocol = FILE;

162 }

163 } 164

165 /* Used internally to retrieve .class files from a web server */

166 private byte [ ] retrieveHTTPClass (String classname) throws ClassNotFoundException {

167 try {

168 // first we will try to load the agent using its fully qualified class

169 // name. If the HTTP URL was http : //host/Agents and the class name

170 // was test .TestAgent, we will build an URL like the following;

171 // http: //host/Agents/test/TestAgent. class

172 URL classUrl = new UR (itsURL + "/" + classname . replace ('.' , '/') + ".class"); 173

174 MeteredStream stream = (MeteredStream) classUrl . getConten () ;

175 int length = stream. available () ;

176 byte dat [ ] = new byte [length] ;

177

178 stream. read (data) ;

179 return data;

180 } catch (IOExcepticn io rror) {

181 // The fully qualified class name didn't work, so letε try to

182 // εtri off all of the pacakge names and εearch for just the

183 // claεs name. If the HTTP URL waε http: //host/Agents and the class name

184 // was test .TestAgent, we will build an URL like the following;

185 // http: //host/Agents/TestAgent .class

186 int lastSep = classname . lastlndexOf ('.') ;

187 if (lastSep != -1) {

188 try {

AgentCodebase . j ava_l Tue Nov 12 03 : 01 : 22 1996 5

189 URL classUrl = new URL(itsURL + "/" + classname . substring (lastSe-

+ 1, classname. length ( i '. -r ".class"); 190

191 MeteredStream stream = (MeteredStream) classUrl . getConten () ;

192 int length = stream. available () ;

193 byte datat] = new byte [ length] ; 194

195 stream. read (data) ;

196 return data;

197 ] catch (Exception error) {

198 throw new ClassNotFoundException ( "Could not load class " + classname + "frcr " + itsURL) ;

199 }

200 } else {

201 tnrow new ClassNotFoundException ( "Could not load class " + classname + "from " + itr RL) ;

202 }

203 } catch (Exception error) {

204 throw new ClassNotFoundException ( "Could not load class " + classname + "from " + itsURL);

205 }

206 }

207 }

AgentConstantβ. java_l Tue Nov 12 08:01:23 1996 1

1 /* $Header: /com/meitca/hsl/zonesjagents/shared/AgentConstants . Java 2 11/11/96 5:25p Billp $

² 3 ^* * Copyright 1996 Hori zon Systems Laboratory,

4 * Mitsubishi Electric Informat ion Technology Center America .

5 * All rights reserved .

6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Constants used by Java Agents system. 11

12 * $Log: /com/meitca/hsl/zonesjagents/shared/AgentConstants . Java $

13 *

14 * 2 11/11/96 5:25p Billp

15 * Made correction to company ame 16

17 * 1 10/10/96 5:50p Walsh

18 * initial version

19 *

20 */

21 package com.meitca .hsl . zoneεjagents . shared; 22

23 import Java. io .File;

26 * Class contains constants used within the Java Agent System.

27 */

28 public class AgentConstants {

29 /**

30 * Contains the value of the "zones.home" property (which

31 * points to the Zones installation directory)

32 */

33 public static String ZONES_HOME; 34

35 /**

36 * Contains the value of the "zones .user .home" property (which

37 * points to the Zones αser specific directory)

38 */

39 public static String ZONES_USER_HOME ;

47 /**

AgentConstants. java_l Tue Nov 12 03:01:23 1996 2

48 * Contains the path of the Agent subdirectory of the Zones

49 * installation directory.

50 */

51 public static String AGΞNT_DIR,

52

53 /**

54 * Contains the path of the lib subdirectory of the Zones/Agents

55 * installation directory

56 */

57 publ ic stat ic String zιGENT_LIB_DIR , 58

59 /**

60 * Contains the path of the Agent subdirectory of the Zones

61 * installation directory

62 */

63 public static String USER_AGENT_DIR, 64

65

66 /** Static Intializer is jsed to initialize some of the CONSTANTS */

67 static {

68 Z0NES_H0ME = System getPropert (" zones home', File separator + "Zones')

69 if (ZONES_HOME '= null/ {

70 // termina e the directroy name with a separator if

71 // it's not already terminated

72 if ( ' ZO •JES_HOME endsWith (File separator))

73 ZONES_HOME += File separator 74

75 IMAGE_DIP = Z0NES_H0ME + "images' + File separator

76 AGENT_DIR = ZONES_HOME + "Agents" + File separator,

77 AGENT_LIB_DIR = AGENT_DIR + "lib" + File separator,

78 } 79

80 ZONES_USER_HOME = System getProperty( zones user home' )

81 ii (ZONES_USER_-iOME == null) {

82 / / the zones user home Property was not defined

83 // try the user home Property

84 ZONES_USER_HOME = System getProperty( "user home",""),

85 -f (ZONES_USER_HOME ^■= null) {

86 // terminate the directroy name with a separator if

87 // t's not already terminated

88 if ( ' ZONES_USER_HOME endsWιth(Fιle separator))

89 ZONES_USER_HOME += File separator, 90

91 ZONES_USER_HOME += " Zones",

92 }

93 } 94

AgentConstants. java_l Tue Nov 12 03:01:23 1996 . 3

95 if (ZONES_USER_HOME != null) {

96 // terminate the directroy name with a separator if

97 // it's not already terminated

101 USER_AGENT_DIR = ZONES_USER_HOME + "Agents" + File . separator ;

102 103 104 }

ClassFileLoader. java_l Tue Nov 12 08:01:23 1996 1

1 /* $Header: /com/meitca/hsl/zonesjagents/shared/ClassFileLoader . Java 3 11/11/96 5:25p Billp $

2 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Loads a ".class" file off of the local filesystem.

11 *

12 * $Log : /com/meitca/hsl/zonesjagents/εhared/ClaεsFileLoader . Java $

13 *

14 * 3 11/11/96 5:25p Billp

15 * Made correction to company name

16 *

17 * 2 9/30/96 6:23p Walsh

18 * clean up javadcc comments

19 *

20 * 1 9/28/96 6:35p Walsh

21 * intial version

22 *

23 */

24 package com. eitca .hsl . zonesjagents . shared;

25

26 import sun . tools . Java .* ;

27 import Java . io . * ,- 28

29 /**

30 * The ClasεFileLoader class loads a Classes bytecodes off of the

31 * local filesystem. The user can either specify a particular directory

32 * from which the bytecodes should be retieved, have the ClassFileLoader

33 * search the system CLASSPATH or specify a custom Clasε Path which should

34 * be searched for the bytecodes. 35 * ©author Thomas Walsh

³⁶ */

37 public clasε ClassFileLoader {

38 /**

39 * The ClaεsPath which should be εearched for ClassFileε. Thiε could

40 * represent the system CLASSPATH, or a custom ClassPath specified by the

41 * user.

42 */.

43 ClassPath itsClasεPath; 44

45 /**

46 * Constructs a ClassFileLoader obj ect . This constructor sets the

47 * ClassFileLoader up εo that it will search the system' s CLASSPATH .

ClassFileLoader. java_l Tue Nov 12 08:01:23 1996 2

48 */

49 public ClassFileLoader ( ) {

50 itsClassPath = new ClasεPath(System. getProperty ( "Java . class .path" ) )

51 } 52

53 / **

54 * Constructs a ClassFileLoader object. The pathstr parameter specifies

55 * a custom ClassPath from which bytecodes are to be retrieved.

56 * ϋparam pathstr A custom ClassPath from which bytecodes are to be

57 * retrieved

58 */

59 public ClassFileLoader (String pathstr) {

60 itsClassPath = new ClassPath (pathstr) ;

61 } 62

63 /**

64 * Loads a class from the objects class path. Depending on which

65 * version of the constructor was used, this could mean that the

66 * system's CLASSPATH is searched or that a custom user-defined

67 * ClassPath iε searched.

68 * Sparam classname The fully qualified class name of the class to

69 * be loaded.

70 * ϋreturn The bytecodes for the requested class in the form of a

71 * byte array

72 * ^exception ClassNotFoundException If the class could not be located on

73 * the ClassPath

74 */

75 public byte [ ] loadClassFileFromClassPath (String classname) throws ClassNotFoundException {

76 String filename = classname . replace ('.' , File . separatorChar) •*- ".class";

77 ClassFile file = itsClassPath . getFile ( filename) ; 78

79 if (file != null) {

80 try {

81 long length = file. length () ;

82 InputStream stream = file .getInputStream( ) ;

83 byte data [ ] = new byte [ (int ) length] ;

84

85 stream. read (data) ;

86 return data;

87 } catch (IOException e) {

88 throw new ClassNotFoundException (e .getMessage ()) ;

89 }

90 } else {

91 throw new ClassNotFoundException ( "ClassFile not found on ClassPath: " + classname) ;

92 }

93 } 94

JASProperties . j ava_l T-te Nov 12 08 : 01 : 23 1996 1

1 / * $Header / coir /mei tca /r s l / zones j agents / shared /JASPropert ies ]ava 4 11 / 11 / 96 5 25p Bi l lp $

3 ² *^* Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Infer- ation Technology Center America

5 * All rights reserved

6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8 *

9 * DESCRIPTION

10 * Zones Agent Property File implementation

11 * $Log /com/rreitca/hsl_/ zones₃agents/shared/JASProperties ;java $ 12

13 * 4 11/11/96 5 25p Billp

14 * Made correctior to company rame

15 *

16 * 3 10/10/96 5 56p Walsh

17 * Make use of constants in AgentConstarts class 18

19 * 2 10/10/96 2 30p Walsh

20 * Add default corstructor

21 *

28 import ]ava 10 *,

29 import ₃ava util * 30

31 /**

32 * The JASProperties supports the storage of

33 * user specific and server specific proDerties

34 * <ul>

35 * <lι>User specific properties are stored in

36 * zones user homeXAgents directory If the

37 * zones user home System property is not defined,

38 * user properties are stored in the

39 * user home\ ZonesXAgents directory

40 * <lι>Server specific properties are stored in

41 * zones home\Agentε\Lιb

42 * </ul>

43 * @see Properties

44 * Θauthor Joe DiCelie

45 * Θauthor Tom Walsh

46 */

47 public class JASProperties extends PropertyFile {

ClassFileLoader. java_l Tue Nov 12 08:01:23 1996 4

151 }

152 }

ClassFileLoader. ava_l Tue Nov 12 08:01:23 1996 3

95 /**

96 * Loads a class from a particular directory.

97 * @param dir The directory from which to retireve the class. If

98 * this parameter is null or an empty string, the ClassPath

99 * is searched for the class

100 * @param classname The fully qualified class name of the class to

101 * be loaded.

102 * Θretur s The bytecodes for the requested class in the form of a

103 * byte array

104 * Θexcepticn ClassNotFoundException If the clasε could not be located on

105 * the ClassPath

106 */

107 public byte[] loadClaεsFileFromDirectory (String dir, String classname) throws ClassNotFoundException {

108 // if a null or an empty string was passed in for dir, ^"fall back to

109 // searching the class path for the clasε

110 if ((dir == null) || (dir . lengthO == 0))

111 return ioadClassFileFromClassPath(classname) ; 112

113 // place a sperator char on the end of the directory specification

114 // if it does not already have one

115 if (! ir .endsWirh (File. separator) ) {

116 dir = dir + File . separator ;

117 118

119 String fullFilaname = dir + classname .replace ('.' , File.separatorChar) + ".class"; I 120

121 try {

122 File file = new File (fullFilename) ; 123

124 if (file. exists!) ) {

125 long length = file. length( ) ;

126 FilelnputStream stream = new FileInputStream( ile) ;

127 byte data[] = new byte [ (int) length] ; 128

129 stream. read (data) ;

130 return data;

131 } else {

132 int lastSep = classname. lastlndexOf ('.') ;

133 if (lastSep != -1) {

134 String filename = dir + classname. subεtring (lastSep + 1, claεsname. length ( ) " .class" ;

135 file = new File (filename) ;

136 long length = file. length ( ) ;

137 FilelnputStream stream = new FilelnputStream(file) ;

138 byte data[] = new byte [ (int) length] ; . 139 140 stream. rea (data) ;

JASProperties . java_l Tue Nov 12 08 : 01 : 23 1996 2

48

49 /**

50 * This constant should be passed into constructor to

51 * specify that this object will contain <b>Server</b>

52 * specific properties.

53 */

54 public static final int SERVER = 0; 55

56 /**

57 * This constant should be passed into constructor to

58 * specify that this object will contain <b>User</b>

59 * specific properties.

60 */

61 public static final int USER = 1 ; 62

63 private static final String PROP_FILE_SUFFIX = ".properties";

64 private static final String DEFAULT_DESC = "Zones Property File"; 65

66 /**

67 * Opens a Properties file and constructε a JASPropertieε object.

68 * Θparam appName A unique name used to identify the application.

69 * The <i>appName</i> is used in constructing the name of the

70 * filename of the corresponding properties file. The

71 * properties file will have a name of the form

72 * "appName .properties"

73 * @param type Idientifieε the type of propertieε file to open.

74 * This parameter can have the value <b>JASProperties .USER</b>

75 * or <b>JASProperties .SERVER</b>. The <i>type</i> parameter

76 * controls where the proerties file is opened from.

77 * <ul>

78 * <li>Uεer specific properties are stored in

79 •* zones .user .homeXAgents directory. If the

80 * zones .user .home System property is not defined,

81 * user properties are stored in the

82 * user .ho e . ZonesXAgents directory

83 * <li>Server specific properties are stored in

84 * zones .homeXAgentsXLib

85 * </ul>

86 * βpara description A description of this JASProperties object.

87 * The description will be written to the header of the

88 * Properties file if the save method is called

89 * Θparam createlfNecessary If set to true, the JASProperties will

90 * create the Properties file if it does not already

91 * exist. If set to false, then the constructor will

92 * throw a FileNotFoundException if the Properties £ile

93 * does not exists.

94 * Sexcepticn FileNotFoundException If the Propertieε file could not

JASProperties. java_l Tue Nov 12 08:01:23 1996 3

95 * be found and the createlfNecessary parameter is false.

96 * Θexception IOException If an error occurred while attempting to

97 * access the Properties file

98 * @excepticn IllegalArgumentException If the value passes into the

99 * type argument was not valid.

100 */

101 public JASProperties (String appName, int type, String description,

102 boolean createlfNecessary)

103 throws FileNotFoundException, IOException, IllegalArgumentException { 104

105 itsDescription = (description != null) ? description : DEFAULT_DESC;

106

107 // Open the default JAS security properties file.

108 itεFile = locatePropertiesFile (appName, type, createlfNecessary); 109

110 loadProperties ( ) ;

111 } 112

113 /**

114 * Builds an "empty" Properties object. This method can be used

115 * to construct a Properties object which returns only default values.

116 * This behavior may be desired if the Properties file can not be found

117 * and the program wishes to continue execution using its default values

118 * or preferences .

119 */

120 public JASProperties () { 121

122 }

123

124 /*

125 * Builds a prperties filename based on the appName and properties

126 * file type

127 */

128 private File locatePropertiesFile (String appName, int type,

129 boolean createlfNecessary)

130 throws IllegalArgumentException, FileNotFoundException, IOException {

131

132 String propDirNa e;

133 if (type == SERVER) {

134 // We are accessing a server properties file.

135 // Server specific properties are stored in

136 // the directory zones .homeXAgentεXLib.

137

138 propDirName = AgentConstants .AGENT_LIB_DIR;

139 } else if (type == USER) {

140 propDirName = AgentConstants . USER_AGENT_DIR;

141 } else {

JASProperties . java_l Tue Nov 12 08:01:23 1996 4

142 throw new IllegalArgumentException ( "Bad Properties File Type: " + type) 143 144 145 146 // See if the propperties directory exists 147 File propDir = new File (propDirName) ; 148 if ( ipropDir .exiεtε () ) { 149 // The directory does not exiεt. 150 // See if we should create it. 151 if (createlfNecessary) { 152 if ( ipropDir .mkdirs () ) { 153 // We could not create the directory. 154 // Throw an IOException 155 throw new IOException ( "Could create properties directory " 156 + propDir . toStringf j

157 } 158 } elεe { 159 // The directory did not exists . 160 // Throw a FileNotFoundException 161 throw new FileNotFoundException ( "Properties directory " 162 + propDir . toString ( ) + " did not exists"), (/ 163 164 165 \ 166 I I see if the properties file exists 167 File propFile = new F le (propDirName + File . separator + 168 appName + PROP_FILE_SUFFIX) 169 if ( ipropFile. exists () ) { 170 // The directory does not exist. 171 // See if we should create it. 172 if (createlfNecessary) { 173 // create the file. 174 FileOutputΞtream out = new FileOutputStream(propFile) ; 175 PrintStream print = new PrintStream(out) ; 176 print .println ( "#" + itsDescription) ,- 177 prin . close ( ) ; 178 // That εhould have created the file 179 } elεe {

186 return propFile; 187

JASProperties. java_l Tue Nov 12 08:01:23 1996 5

188 }

189

PropertyFile.java_l Tue Nov 12 08:01:23 1996 1

1 /* $Header: /ccm/meitca/hsl/zonesjagents/shared/PropertyFile . Java 2 11/11/96 5:25p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Properties (Preference) File object.

11

12 * $Log: /com/meitca/hsl/zonesjagents/shared/PropertyFile. Java $

13

14 * 2 11/11/96 5:25p Billp

15 * Made correction to company name

16 *

17 * 1 10/07/96 5:07p Walsh

18 * intial versions

19 *

20 */

21 package com.meitca .hsl . zonesjagents . shared;

22

23 import java.io.*;

24 import java.util . * ; 25

26 /**

27 * The PropertyFile object extends the behavior of the Properties class

28 * by associating the Properties with a disk file. The PropertyFile

29 * object automatically loads the Proeprties out of the file (using the

30 * Properties . load method) and supplies a method for saving of any updated

31 * Properties back to disk, called saveProperties .

32 * Θsee Properties

33 * Θauthor Joe DiCelie

34 * ©author Tom Walsh

35 */

36 public class PropertyFile extends Properties {

37

38 /** The name of the properties file corresponding to this Properties object */

39 protected File itsFile;

40

41 /** A description of this Properties object. */

42 protected String itsDescription;

43

44

45 /**

46 * Opens the specified Properties file and constructs a

47 * JASProperties object.

PropertyFile. java_l Tue Nov 12 08:01:23 1996 2

48 * βparam propertiesFileName Name of the Properties file to open

49 * ©param description A description of this JASProperties object.

50 * The description will be written to the header of the

51 * Properties file if the save method is called

52 * Sexception FileNotFoundException If the Properties file could not

53 * be found and the createlfNecesεary parameter is false.

54 * Sexception IOException If an error occurred while attempting to

55 * access the Properties file

56 */

57 public PropertyFile (String propertiesFileName, String description)

58 throws FileNotFoundException, IOException { 59

60 itεFile = new File (propertiesFileName) ;

61 itsDeεcription = deεcription;

62 loadProperties ( ) ,-

63 } 64

65 /**

66 * Protected constructor that can be used by derived classes.

67 */

68 protected PropertyFile ( ) {

69 itsFile = null;

70 itεDescription = n ll;

71 // The actual work of loading properties will be

72 // done by derived class

73 } 74

75

76 // loads Properties from the Properties File

77 protected void loadPropert; es ( )

78 throws FileNotFoundException, IOException { 79

80 // open an input stream to the file specified

81 FilelnputStream in = new FilelnputStrea ( itsFile) ; 82

83 // load the propertieε

84 load (in) ;

85 }

86

87 /**

88 * Saves the Properties to the corresponding Properties File

89 * Sexception FileNotFoundException if the Properties file could not be

90 * located

91 * Sexception IOException if an error occurs while accessing the

92 * properties file

93 */

94 public void savePropertieε ( )

PropertyFile. ava_l Tue Nov 12 08:01:23 1996 3

95 throws FileNotFoundException, IOException {

96

97 // open an input stream to the file specified

98 FileOutputStream out = new FileOutputStream(itsFile) ;

99

100 // load the properties

101 save (out, itsDescription) ;

102 } 103

104 /**

105 * Refreshes the Properties object by re-reading the Properties File. Any

106 * changes made to the Properties object will be lost.

107 * Sexception FileNotFoundException if the Properties file could not be

108 * located

109 * Sexception IOException if an error occurs while accessing the

110 * properties file

111 */

112 public void refreshProperties ( )

113 throws FileNotFoundException, IOException {

114 loaάProperties ( ) ^■

115 } 116

117

118 }

119

120

121

122

AgentClassInfoGatherer. java_l Tue Nov 12 07:44:46 1996 1

1 /* $Header /com/me: .ca hsl/zones₃agents/bootstrap gentClassIn oGatherer ]ava 5 11/11/96 5 13p Billp $

2 *

3 * Copyright 1996 -iorizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America

7 * CONFIDENTIAL AND ^PRO^PRIETARY PROPERT 0" MITSUBISHI ELECTRIC ITA 8

9 * DESCRIPTION

10 * AgentClassInfoGatherer class peeks ιi:o an agents class file to

11 * retrieve information needed for agert icjnchmg 12

13 * SLog ^/com/ e.tca/hsl/zones]age"ts bootstrap/AgentClassInfoGatherer ₃ava $

14 *

15 * 5 11/11/96 5 _-p Billp

16 * Made correction to company name

17 *

19 * fix up ]avadoc

20 *

21 * 3 9/27/96 6 _0„ Dxcelie

22 * Minor cnange to loop uhich verified fi t tne class to be launched was

23 * subclasses from ? ~~ ~

24 *

25 * 2 9/10/96 11 46a Walsh

26 * remove bogus imports that ₃avac illegal 27

28 * 1 8/29/96 5 20o ' lsh

29 * ntiai version 30

31

32 package com n«=^tca hs^"1 zςnes]agents bootstrao 33

34 import }ava 10 *

35 import com meitca hsl zo^esj ge^ s cona..: -gentSkeletor 36 37 /**

38 * This ob₃ect peeks irto the class file of an agent to retrieve

39 * some information needed for launching the agent

40 * AgentClassInfoGatherer verifies that the class file indicated

41 * does contain a class oeπved from Agent and then it verifies the

42 * existence of the agsnt's invocation skeleton and finally loads

43 * the skeleton class ι-tc memory and retreives a list of the

44 * agents methods froi the skeleton

45 * θεee Agent

46 * Sεee Bootstrap

47 * Sεee AgertLa _^nchWizard

AgentClassInfoGatherer. ja-va l Tue Nov 12 07:44:46 1996

48 * Sauthor Tl orras a_^ sh

49 * /

50 public class Ager .ClεsslnfoGatherer {

51 /** The r-mes of tne agents methods */

52 String!] itsAgentsMethods ,

53 54

55 /**

56 * Constructs a AgentClassIn oGatnerer object Loads the agent

57 * and its s eletor Retrieves a list of the agent's methods

58 * (sparan agentDir The directory containing the agent's

59 * class file

60 * (?para:ι agentFilename The name of the agents 's class file

61 * (sexcepti n F_ .eNotFoundΞxcεption Thrown if the class specified

62 * could not oe opened

63 * (Sεycepticr IOException f an 10 error occurs vπle teymg to

64 * access tne agent's class file

65 * ssForrnatErrcr If tne agent's c.ass file αoes

66 * not contain a valid class

67 * ϋeicepticn NotAgentException If the agent's class file does

68 * not contain an agent

69 * (Jexcppticn ClassNotFoundException If an error occured while

70 * trying to access the agents class file

71 * Sexception No^gentSkeletonException If the agent's invocation

72 * skeleton could not be found

73 */

74 public AgentClassIn oGatherer (String agentDir, String agentFilename)

75 thr >ws FileNotFoundException, IOException, ClassFormatErrcr ,

76 NotAgentException, ClassNotFoundException,

77 NoAgentSkeletonException {

78 ' ' let the loadAgentClasεln o method do all of the real work

79 _ dAgentClassInfo (agentDir , agentFilename),

80 } 81

82 /**

83 * Ver-fies tne existence and correctness of the agent class file

84 * and the agert's skeleton Retrieves a list of the agent's methods

85 * Calle ..ntrnalii by the constructor

86 * (sparaπ agentDir The directory containing the agent's

87 * class file

88 * @param agentFilename The name of the agents' s class file

89 * @except4.on FileNotFoundException Thrown if the agent's class

90 * did not exist.

91 * ©exception IOException If an 10 error occurs while teymg to

92 * access the agent's .class file.

93 * ©exception Cla?sFormatError If the agent's class file does

94 * not contain a valid class.

AgentClassInfoGatherer. ja-va_l Tue Nov 12 07:44:46 1996 3

95 * @except_on NotAgentException If the agent's .class file does

96 * not contain an agent.

97 * ©exception ClassNotFoundException If an error occured while

98 * trying to access the agents class file.

99 * ©exception Nc.-.gentSkeletonException If the agent's invocation

100 * skeleton could not be found.

101 */

102 private void loadAcentClassInfo (String agentDir, String agentFilename)

103 throws FileNotFoundException, IOException, ClassFormatError ,

104 NotAgentException, ClassNotFoundException,

105 NoAgentSkeletonΞxception { 106

107 // load the Agent class

108 ScotStrapCLassLoader ClassLoader = new BoctStrapClassLoader (agentDir ) ,

109 Class agent = ClassLoader . loadAgentClassFromFile (agentFilename, true) ; 110

111 '/ ve-ify that it iε actually an Agent

112 L-ass superclass = agent getSuperclass () ; 113

114 '/ STABILITY: Any way to get these hard coded strings out of here'

115 String s perClassName,

116 do 117

118 s-perC assName = superclass getName ( ) ,

119 if (superClasεName . equalε ( "₃ava . lang .Object ") ) {

120 throw new NotAgentException (agentFilename ■>^■ " does not contain an agent");

121 } 122

123 superclass = superclass getSuperclass () ,

124

125 } while ('superClassName equalε("com meitca hsl zones₃agents shared .Agen ")) ,

126

127 '/ ck, we have an agent

.28 // lets t to load the skeleton

_29 try {

130 // first lets strip the " class" from the filename

131 STABILITY: Any way to get tnese hard coded strings out of here''

132 String skelClassFileName = agentFilename . substring ( 0 ,

133 agentFilename . length ( ) - ".class" lengthO),

134

135 // append on the _Skel

136 skelClassFileName = skelClassFileName + "_Skel . class " ; 137

138 // now try to load the skeleton class

139 Class skelClass = ClassLoade . loadAgentClassFromFile (skelClassFileName, true) 140

141 // finally retrieve the agents methods.

AgentClasslnfoGatherer. ava_l Tue Nov 12 07:44:46 1996 4

142 Ager.tSkeleton skel = (AgentSkeleton) skelClass . newlnεtance ( ) ;

143 its gentsMethods = skel .getMethods ( ) ;

144 } catch (Exception e) {

145 throw new ClasεNotFoundException ( "Could not find skeleton for agent " + agentFilename)

146 }

147 } 148

149 /**

150 * Retrieves a list of the agents methods. This list is used

151 * by the Agent Launch GUI in order to preεent the user with

152 * a drop down list containing the eligible methods of the agent.

153 */

154 public String!] getAgentMethods ( ) {

155 return itsAgentsMethods;

156 }

157 }

AgentLaunchlnformati;n.java_l Tue Nov 12 07:44:46 1996 1

1 /* $Header: /com/meitca/hsϊ -'zonesjagents/bootstrap/AgentLaunchlnformation . Java 4 11/11/96 5:13p Billp $ 2

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * AgentLaunchlπformation encapsulates the information needed to

11 * bootstrap the agent into the system.

12 *

13 * $Loc : /com/meitca/hs ../zonesjagents/bootεtrap/AgentLaunchlnformation . Java $ 14

15 * 4 11/11/96 5:I3p Billp

16 * Made correction tc company name. 17

18 * 3 9/33 '96 6:35p Walsh

19 * fix up javaaoc comments 20

21 * 2 9/11/96 4:46p Walsh

22 * add itsAσent member

23

24 * 1 8/29 S o 5:21p Walsh

25 * intial version 26

27 */

28 package com ..r.ei tea . hsl . zonesjagents . bootstrap ; 29

30 import com.meitca .hsl . zoneε;^'agents .conduit . Itinerary;

31 import com.rr.aitca .hsl . zones;agents . shared .Agent ; 32

33

34 /**

35 * The Agent aunchlnformation class encapsulates the information

36 * needed by the Bootstrap class in order to launch and Agent.

37 * This class is used internally by the AgentLaunchWizard and

38 * the Agent command li e launch tool. 39 * ©see Agent 40 * ©see Bootstrap

41 * ©see AcentLaunchVϊizard

42 * ©author Thomas Waiεh

43 */

44 public class AgentLaunchlnformation {

45 /**

46 * The directory (on the local host) containing the agent's

47 * .class file as well as the .class files of any related

AgentLaunchlnformation. java_l Tue Nov 12 07:44:46 1996

48 * classes.

49 '/

50 public String itsAgentDirectory;

51

52 /** The agent's .class file */

53 public String itsAgentFile ;

54

55 /'*

56 * Ar array containing the filenames of any other classes

57 * that should be sent along with the agent. The ConduitServer

58 * has the ability to communicate back to the agents home machine

59 * to retrieve classes needed at runtime (if the RemoteLoader server

60 * is running) . Kith this parameter a programmer can bypass this

61 * and send any needed classes up front.

62

63 public String!] itsRelatedClaεεes ,-

64

65 /** The agents Itinerary */

56 public Itinerary itsltinerary;

67

68 /**

69 * T".e agent itself. This member on needs to be filled in if the

70 * C3_ler wants to call a method on the agent other than the default

71 * constructor. If this field is left blank, then the

72 * Bootstrap . launchAσent method will constuct the Agent contained in

73 * the file itsAgentDirectory by calling its default constructor.

74 * This method gives the programmer the option of constructing an

75 * agent with a ctc other than tne default.

76 */

77 public Agent itsAgent,

78

79 /**

80 * A listing of the agents methods. This member variable need not

81 * be filled in in order to launch the agent, but is uεed internally

82 * ry the Agent aunchWizard

83 */

84 public String!] itsMethods;

85

86 /** Constructs an empty AgentLaunchlnformation object */

87 pub; ic AgentLaunchlnformation ( ) {

88 itsAgentDirectory = new String ("")

89 itsAgentFile = new StringC'");

90 itsltinerary = new Itinerary () ;

91 itsAgent = null;

92 }

93 }

AgentLaunchWizard. ja-va_l Tue Kov 12 07:44:46 1996 1

1 /* $Header. /ccn/meitca/hεl/zoneεjagents/bootstrap/AgentLaunchWizard. ava 10 11/11/96 5 13p Billp $

2 *

3 * Copyright 1996 Horizon Systemε Laboratory,

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA 8 9 * DESCRIPTION

10 * GUI tool for launcmc agents into system

11

12 * $Log com/meιtca/hε l/zones₃agents/bootstrap/AgentLaunchWιzard ]ava $

13

14 * 10 11.11/9-: 5 13p Billp

15 * Made correction to company name 16

17 * 9 10 _'10 '96 5:57p Wals.

18 * Make use of properties JΓ AgentConstants clasε

19 *

20 * 8 10 08/96 10 21a Walsh

21 * Fix name collision oetween bootεtrap StrmgResourceε and

22 * util StπngReεourceε

25 * Save name & ocation o I sst agent launched Reεtart Wizard pointing

26 * at same sgei 27

28 * 6 1C 0^"/ 96 3 55p Walsn

29 * Set up c"ie to look in zones .home\ images for GIF file 30 31 * 5 9, 3 '96 6 35p Walsh

32 * fix up j vadoc comments 33

34 * 4 9/27/96 11:52a Walsn

35 * print exception to stderr on LaunchException 36

37 * 3 9/C9/96 3.46p Walsh

38 * replace gj t .MessageDialog with com meitca. hsl util InfoDialog. Create 39 * Security Manager m am 40

41 * 2 9/C4/96 12-34p Walsn

42 * Pop up c _^alog on any problems launching the agent

43 *

44 * 1 8/2 9 / 96 5 : 21p Walsh

45 * intial vers i on 46

47 * /

AgentLaunchWizard. ava_l Tue Nov 12 07:44:46 1996 2

48 package con ηreitca hsl zores₃agents bootstrap, 49

50 import ₃ava awt *

51 import ₃ava 10 *

52 import ₃ava v-til * 53

54 import com meitca hsl zi x *,

55 import com me¹ tea hsl zoreε;agents secunty *,

56 import com rsitca hεl shared *, 57

58 /**

59 * The AgentLaunchWizard prc-zides a wizard-like GUI for launching

60 * Java Agentε into tne system

61 * ©see Agert

62 * ©see Bootstrap

63 * ©see AgentLaunchlnformation

64 * ©see Wizard

65 * ©author Thomas Walsn

66 */

67 public class AgentLaunc-iWizsrd extends Wizard {

68 /** The launch information */

69 AgentLaunchln ormation ltsAgentlnfo,

70

71 /** Tne filename of the GIF */

72 static final String GIF_FILENAME = AgentConstants IMAGE_DIR + "AgentLaunchWizard gif ' , 73

74 /** Properties (Preference) object */

75 J^SF perties itsProperties 76

77 stati- fin zones agent bootstrap LastAgentDir '

78 static fin ' zones agent bootstrap LastAgentFile'

79 // Static irit_^alxzer 80

81 /**

82 * Constructs an AgentLaunchWizard object Bπngε up the GUI and

83 * sets up the first panel

84 */

85 public AgentLaunch^Wizard ( ) {

86 stper(com meitca hsl zoneε₃agentε bootεtrap StnngResources WIZARD_TITLE

87 GIF_FILENAME) ,

88 ltsAgentlnfo = new AgentLaurchlnformation () ,

89 90 try {

91 itsProperties = new JASProperties (

92 com. eitca hsl zones₃agents bootstrap StnngResources WIZARD_ PPNAME,

93 JASProperties USER,

94 com meitca hsl zones₃agents bootstrap StnngResources PR0P_DESC,

AgentLaunchWizard. java_l Tue Nov 12 07:44:46 1996 3

95 true) ;

96 } catch (Exception e) {

97 itsProperties = null;

98 }

99

100 if (itsProperties != null) {

101 itsAgentlnfo. itsAgentDirectory = itsProperties .getProperty (LAST_AGENT_DIR, "");

102 itsAgentlnfo. itsAgentFile = itsProperties .getProperty (LAST_AGENT_FILE, "");

103 } 104

105 buildPanels ι ) ;

106 f irstPanel ( I ; 107

108 resize(570, 370) ;

109 show ( ) ;

110 } 111

112 /**

113 * Builds the panels of the wizard. The AgentLaunchWizard

114 * contains three panels 1) a panel for specifying the agent's .clasε

115 * ϊiLs (nameε Fi dFilePanel) , 2) a panel for specifying the related

116 * class files for sending with the agent (called RelatedFilesPanel) and

117 * 3) a panel for setting up the agents itinerary (called ItineraryPanel)

118 */

119 protected void buildPanels ( ) {

120 FindFilePanel panell = new FindFilePanel (this , itsAgentlnfo);

121 RelatedFilesPanel panel2 = new RelatedFilesPanel (this, itsAgentlnfo);

122 ItineraryPanel panels = new ItineraryPanel ( his, itsAgentlnfo);

123 } 124

125 /**

126 * The finish method is called by the Wizard base claεε when the

127 * user has successfully filled all the necessary information

128 * into all the panels and haε preεεed the "Finiεh" button. We now

129 * have all of the information we need εo we'll try to launch the agent.

130 */

131 protected void f ir.i εh O {

132 try {

133 // launch the agent

134 Bootstrap. launchAgent ( itsAgentlnfo) ;

135

136 if (itsProperties != null) {

137 try {

138 itsProperties. put (LAST_AGENT_DIR, itsAgentlnfo . itsAgentDirectory) ; 139 itsProperties. put (LAST_AGENT_FI E, itsAgentlnfo . ItsAgentFile) ;

140 itsProperties . saveProperties ( ) ;

141 } catch (Exception e) {

AgentLaunchWizard. java_l Tue Nov 12 07:44:46 1996 4

142 }

143 } 144

145 /.' shutdown.

146 cancel ( ) ;

147 } catch (LaunchException e) {

148 InfoDialog info = new InfoDialog (this,

149 com.meitca. hsl . zonesjagentε .bootstrap . StnngResources .LAUNCH_ERROR_TITLE,

150 com. meitca. hsl . zonesj gents .bootstrap. StringReεourceε ,LAUNCH_ΞRROR) ;

151 info . setBackgroun (Color . lightGray) ;

152 i fo .εhow() ; 153

154 System, err.printlr. (e .getMesεage ( ) ) ;

155 e-printStackTrace () ;

156 }

157 } 158

159 /**

160 * main routine supplied εo that AgentLaunchWizard can be initiated

161 * from the command line

162 */

163 public static void main (String argε [ j ) {

164 / .' Create and install the security manager

165 System. setSecurityManager (new InsecurityManager ( ) ) ;

166

167 AgentLaunchWizard gui = new AgentLaunchWizard () ;

168 } 169

170 }

AgentLaunohWizardPanel . j ava_l Tue Nov 12 07 : 44 : 47 1996 1

1 / * $Header : ,' com/me i tca/hε l / zones j agents /boots trap/AgentLaunchWi zardPanel . J ava 4 11 / 11 / 96 5 : 13p Bi llp $

2 *

3 * Copyright 1596 Horizon Systems Laboratory,

4 * Mitsubiεhi Electric Information Technology Center America.

5 * All rights reserved.

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA. 8

9 * DESCRIPTION

10 * A subclaεs of WizardPanel for use in the AgentLaunchWizard

11 *

12 * $Log : /com/meitca/hsl/zonesjagents/bootstrap/AgentLaunchWizardPanel . Java $

13 *

14 * 4 11/11/96 5:13p Billp

15 * Made correction to company name.

16 *

17 * 3 9/30/96 6:35p Walsh

18 * fix up javadoc comments

19 *

20 * 2 9/10/96 11:46a Walsh

21 * remove bogus imports that javac considers illegal

22

23 * 1 8/29/96 5:21p Walsh

24 * intial version

25 *

26 */

27 package com. eitca .hsl . zonesjagentε .bootεtrap; 28

29 import j av . wt . * ; 30

31 import com.meitea .hsl .util .Wizard,-

32 import com. eitca .hsl .util .WizardPanel ; 33

34

35 /**

36 * AgentLaunchWizardPanel is a base class for the panels of the

37 * AgentLaunchWizard. All of the panels in the launch wizard need

38 * shared access to the AgentLaunchlnformation object describing the 39 * parameters of the launch. This base claεε provideε that

40 * access .

41 * ©see Agent

42 * ©see Bootstrap

43 * ©see AgentLaunchlnformation

44 * ©see AgentLaunchWizard

45 * ©author Thomas Walsh

46 */

47 public class AgentLaunchWizardPanel extends WizardPanel {

AgentLaunchWizardPanel. τ"ava_l Tue Nov 12 07:44:47 1996 .

48 /** The launch parameters of the Wizard*/

49 protected AgentLaunchlnformation itsAgentlnfo;

50

5511 52 Constructs an AgentLaunchWizardPanel. 53 ©parain wizard The Wizard owning this panel (needed by super) 54 ©param info The (shared) reference to the agent launch infomarion 55 */ 56 public AgentLaunchWizardPanel (Wizard wizard, AgentLaunchlnformation info) { 57 super (wizard) ; 58 itsAgentlnfo = info; 59 } 60 61

Bootstrap.java_l Tue Nov 12 07:44:47 1996 1

1 /* $Header: /com/meitca/hsl/zonesjagents/bootstrap/BootStrap . Java 11 11/11/96 5:13p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved. 6

7 * CONFIDENTIAL AMD PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Module for boot strapping agents into the system.

11 *

12 * $Log : /com/meitca/hsl/zonesjagents/bootstrap/BootStrap. Java $ 13

14 * 11 11/11/96 5:13p Billp

15 * Made correction to company name. 16

17 * 10 10/01/96 10:39a Walsh

18 * fix ©exception javadoc tag

19 *

20 * 9 9/30/96 7:33p Walεh

21 * add more javadoc

22 *

23 * 8 9/28/96 6:56p Walεh

24 * Add new version of launchAgent

25 *

26 * 7 9/11/96 4:59p Walsh

27 * allow launchlnfo . itsRel tedClasseε to be null 28

29 * 6 9/11/96 4:46p Walsh

30 * if caller specified Launchlnfo . itsAgent, use that rather than

31 * constructing a new one. 32

33 * 5 9/10/96 11:46a Walsh

34 * remove bogus imports that javac considers illegal

35 *

36 * 4 9/09/96 3:46p Walsh

37 * Move creation of SecurityManager to main to prevent error on multiple

38 * calls to Launch

39 *

40 * 3 9 / 05 / 96 6 : 38p Walsh

41 * Add a main method to handle command line agent launching

42

43 * 2 9/04/96 12:35p Walsh

44 * Add some exception handling. Let ConduitServer handle details of

45 * launching agent. Let RemoteLoader build up the home codebase URL

46 *

47 * 1 8/29/96 5:21 Walsh

Bootstra .java_l Tuβ Nov 12 07:44:47 1996

48 * mtial version 49

54 import ₃ava rπ server StubSecurityManager, 55 import jav rri server MarshalOutputStream, 56 import ₃ava net TnetAddress 57 import ]ava util *, 58 import ]ava 10 *, 59 60 import com meitca hsl zones;agents shared *, 61 import com me tea hsl zones;agents conduit ConduitServer, 62 import com meitca hsl zones; agents conduit AgentPackage, 63 import com meitca hsl zonesπagents conduit Itinerary, 64 import com meitca hsl zoneε;agents conduit MobileCodebase, 65 import com meitca hsl zores;agents conduit ConduιtOb₃ectOutputStream, 66 import com meitca hsl zones;agents conduit Destination 67 import com meitca hsl zones;agents conduit ConduitServerlmpl , 68 import com meitca hsl zonesjagents remoteloader RemoteClassLoaderlmpl 69 import com me_tca hsl zones., gentε security InsecurityManager 70 71 72 73 74 * Bootstrap provides a mechanism for boot strapping (launching) agents 75 * into the system The caxlmg program must provide the launch parameters 76 * in the for^1-' of the Agert_,aunchlnformation object Bootstrap takes this 77 * information and provides the necessary εtepε to launch the indicated agents 78 * This includes building creating the MobileCodebase loading any needed 79 * classes (i ducing the aαent) into the MobileCodebase constructing the 80 * AgentPackage contacting the mtial ConduitServer and sending the agent 81 * ©see Agent 82 * ©see AgentLaunchlnformation 83 * ©author Thomas Walsn 84 */ 85 public class Bootstrap { 86 * * 87 * Launches an agent 88 * ©pararn agent The agent to launch 89 * Θparam itinerary The agent's itinerary 90 * Srara agentCodebaseURL An URL pointing to the codebase of the agent 91 * This URL can take the following forms, 92 * <ul> 93 * <lι>A file URL like <b>fιle C \agents</b> - which indicates that th 94 * agent's code is located on the local machine in the directory

Bootstrap. ava_l Tue Nov 12 07:44:47 1996

95 <b>C \agent</b>

96 <lι>An HTTP URL like <b>http /hostname/agents</b> - which indicates a

97 location on a web server from which the agents code can be

98 retrieved (This is very similar to the codebase modifier

99 which can be added to an HTML <b>&ltapplet&:gt</b> tag) 100 <lι>An RMI URL like <b>rmι /hostname/RemoteClassLoader</b> pointing 101 to a RemoteClassLoader object which can retrieve the agents code <br> 102 Thiε RMI URL could also look like 103 <b>rmι /hostname/RemoteClassLoader/C \agents</b> which indicates that 104 the RemoteClassLoader on hostname should be uεed to retrieve 105 the classes and that the agents code is located in the <b>C \agents</b> 106 directory 107 </ul> 108 * fcaian relatedClasses An array of fully qualified claεεnameε of classes which this agent makes 109 use of Theεe classes will be set up to travel with the agent 110 * ©exception LaunchException is the agent could notbe launched 111 */ 112 public :ιc voic launchAgen (Agent agent, Itinerary itinerary. String agentCodebaseURL, 113 Strmg[] relatedClasseε) throws LaunchExcep- on { 114 try { 115 MobileCodebaεe agentCode = new MobileCodebaεe ( ) , 116 Boo-StrapClasεLoader bootstrap = new BootStrapClaεεLoader (agentCodebaseURL, 117 agentCode) , 118 DootStrap loaαAgentClaεs (agent getClasε() getName(), false), 119 120 if (relatedClaεεes '= null ) { 121 for (int ι=0, ι<relatedClasses length, ι++) 122 Class related = bootstrap loadAgentClasε (relatedClasseε [ l ] , false), 123 } 124 125 String absoluteCodebaseURL, 126 if (agentCodebaseURL ' = null) { 127 if ('agentCodebaseURL startεWith ( 'rmi ") && ' agentCodebaεeURL starts.i th ( "http ")) 128 if (agentCodebaseURL startεWith ( ' f ile ")) { 129 abεoluteCodebaεeURL = RemoteClaεεLoaderlmpl buildCodebaεeURL ( 130 InetAddress getLoca ost() getHostName ( ) ,

131 agentCodebaεeURL εul tring (5, agentCodebaεeURL length ( ) ) ) 132 } else { 133 abεoluteCodebaεeURL = RemoteClassLoaderlmpl buιldCodebaseURL( 134 InetAddress getLoca oεt() getHostName ( ) 135 agentCodebaseURL) , 136

Bootstrap. java_l ?ue Nov 12 07:44:47 1996 4

137 } elεe {

138 absoluteCodebaεeURL = agentCodebaεeURL;

139 }

140 } elεe {

141 absoluteCodebaseURL = RemoteClaεεLoaderlmpl . buildRmiURL (

142 InetAddresε . getLocalHost ( ) . c tHostNameO ) ;

143 } 144

145 AgentPackage agentPackage = new AgentPackage (agent ,

146 agen: Code,

147 iti rary,

148 abεo uteCodebaεeURL) ;

149 150

151 // pass the agent along

152 ConduitServerlmpl . εendPackage (agentPackage) ;

153

154 } catch (Exception error) {

155 throw new LaunchException ( "LaunchΞxception : " + error . getMessage ()) ;

156 }

157 } 158

159 /**

160 * Launches an agent based on the given launch parameters

161 * ©para launchlnfo The launch parameters

162 */

163 public static void launchAgent (AgentLaunchlnformation launchlnfo) throws LaunchException { 164

165 try {

166 MobileCodebase agentCode = new MobileCodebaεe () ^■

167 BootStrapClaεsLoader bootstrap = new BootStrapClassLoader ( launchlnfo . itsAgentDirectory, 168 agentCode) ;

169 Class agentClasε = bootstrap. loadAgentClassFromFile (launchlnfo . itsAgentFile, true);

170

171 if (launchlnfo. itεRelatedClasseε != null ) {

172 for (int i=0; i<launchInfo . itsRelatedClasεes . length; i++)

173 Class related = bootstrap . loadAgentClassFromFile ( launchlnfo . itsRelatedClass [i], true);

174 } 175

176 String codebaseURL = RemoteClasεLoaderlmpl .buildCodebaseUR (

177 InetAddress .getLocalHost () .getHoεtN.'i

Bootstrap. java_l Tue Nov 12 07:44:47 1996

178 launchlnfo . itεAgentDirectory) ;

179

180

181 Agent agent;

182 if (launchlnfo . itεAgent == null) {

183 agent = (Agent ) agentClasε . newlnstance () ;

184 } else {

185 agent = launchlnfo . itsAgent ;

186 }

187 AgentPackage agentPackage = new AgentPackage ( agent ,

188 ager. ^• Code,

189 lau.. hlnfo . itsltinerary,

190 code . aseURL) ;

191

192

193 // pasε the agent along

194 ConduitServerlinpl . εendPackage (agentPackage) ;

195

196 } catch (Exception error) {

197 throw new LaunchException ( "LaunchException : " + error . getMessage ()) ;

198 }

199 } 200

201 /**

202 * Th s method gets invoked when a user tries to launch an Agent from

203 * the command line. The command line should look something like the

204 * fcllowing;<br>

205 * <pre> 206

207 * Usage: bootstrap [ -d hostname, ethod] [-f relatedfile . claεε] [-h] agentfile . class 208

209 * </prexbr>

210 * The user specifies the agent class file as the last parameter to

211 * the command. The destiantions for the Agent are specified with the

212 * <b>-d</b> option. A destination is specified by the hostname followε by a

213 * comma (no space) -followed by the name of the method to invoke.

214 * This could look something like the following; <b>-d hostl, agentMethodl</b> .

215 * The user specifies related class files that should be sent with the

216 * agent using the <b>-f</b> option. Finally, the <b>-h</b> option brings up

217 * some command line help.

218 */

219 public static void main (String args [ ] ) {

220 // Create and install the security manager

Boo strap . j ava_l Tue Nov 12 07:44:47 1996

221 System. εetSecurityManager (new InsecurityManager ( ) ) ; 222 223 // We start by doing some rather brute force parsing of the 224 // command line. The command line args are used to build up 225 // an AgentLaunchlnformation data structure. 226 AgentLaunchlnformation launchlnfo = new AgentLaunchlnformation ( ) 227 Vector destinationStrings = new Vector (); 228 Vector relatedFiles = new Vector (); 229 String agentFile = null; 230 231 for (int i=0; i<args . length; i++ ) { 232 if (argsfi] .equals C-d") ) { 233 String destinationString = args[++i]; 234 destinationStrings .addElement (destinationString) 235 continue; 236 } else if (args [ i] . equals (" -f" ) ) { 237 String fileName = args[++i]; 238 relatedFiles .addElement (fileName) ; 239 continue; 240 } else if (args [i] . equals (" -h" ) ) { 241 System. out .printIn (StnngResources .USAGE) ; 242 return; 243 } else { 244 if (argεfi] .charAt(O) == '-') { 245 System. out .println (StringResources . ILLEGAL_OPTN + argε[i]) 246 System. out .println (StringResources .USAGE) ; 247 return ; 248 } else { 249 agentFile = argε[i] 250 } 251 252 } 253 254 // firεt lets verify that we have a valid agent file, 255 if (agentFile == null) { 256 System. out .println (StringResources . O_AGENT) ; 257 System. out. println (StringResources .USAGE) ; 258 re urn;

259 }

260

261 if ( ! gentFile. endsWith(" .class") ) {

262 System. out.println (StringResources. ILLEGAL_AGENT + agentFile);

263 System. out. println (StringResources. AGENT_HELP) ;

264 return;

265 1

266

267 launchlnfo . itsAgentDirectory = new String!"")

Bootstrap. java_l Tuβ Nov 12 07:44:47 1996 7

268 launchlnfo. itsAgentFile = agentFile;

269

270 for (int i=agentFile . length () -1 ; i>=0; i--) {

271 if (agentFile. charAt(i) == File . separatorChar ) {

272 launchlnfo. itsAgentDirectory = agentFile . substring (0 , i+1) ;

273 launchlnfo. itsAgentFile = agentFile . substring ( i+1, agentFile . length ()) ;

274 break; "

275 }

276 } 277

278 // Now let the AgentClassInfoGatherer verify the existence of the file,

279 t I that the file contains a valid Java Agent and that the skeleton

280 // exists.

281 cry {

282 AgentClassInfoGatherer agentlnfoGatherer = new AgentClassInfoGatherer (

283 launchlnfo. itsAgentDirectory, launchlnfo . itsAgentFile) ; 284

285 launchlnfo . itsMethods = agentlnfoGatherer .getAgentMethods () ;

286 } catch (FileNotFoundException el) {

287 System. out. println (StringResources. ILLEGAL_AGENT + agentFile);

288 System. out .println ( "\t" + StringResources .FILE_NOTFOUND) ;

289 return; i

290 } catch (IOException el) {

291 System. out .println (StringResources . ILLEGAL_AGENT + agentFile);

292 System. out .println (" \t" + StringResources . IOERROR) ;

293 return;

294 } catch (ClasεFormatError el) {

295 Syεte . out .println (StringReεourceε . ILLEGAL_AGENT + agentFile);

296 System. out .println (" \t" + StringResources .BAD_CLASS_FORMAT) ;

297 return;

298 } catch (NotAgentException el) {

299 System. out .println (StringResources . ILLEGAL_AGENT + agentFile);

300 System. out .println (" \t" + StringResources .NOT_AGENT) ; 301 return;

302 } catch (ClassNotFoundException el) {

303 System. out .println (StringResources . ILLEGAL_AGENT + agentFile);

304 System. out .printlnf "\t" + StringResources .BAD_CLASS_FORMAT) ; 305 return;

306 } catch (NoAgentSkeletonException el) {

307 System. out .println (StringResources . ILLEGAL_AGENT + agentFile);

308 Syεtem. out. println( "\t" + StringResources .NO_SKELETON) ; 309 return;

310 } 311

312 / / Lets take a look at the related f iles

313 launchlnfo . itsRelatedClasses = new String [relatedFiles . size ( ) ]

314 for ( int i=0 ; i< relatedFiles . size ( ) ; i++ ) {

BootStra . java_l Tuβ Nov 12 07:44:47 1996 8

315 String fileName = (String) relatedFiles .elementAt (I) , 316 if (fileName endsWιth(" class")) { 317 launchlnfo ltsRelatedClasses [ l] = fileName, 318 } else { 319 System out printl (StringResources ILLEGAL_RELFILE + fileName) , 320 System out println (StringResources RELFILE_HELP) ; 321 return, 322 } 323 i 324 325 I I Finally, lets take a look at those destinations 326 if (destinationStrings sιze() == 0) { 327 System out println (StringResources NO_DEST) , 328 return, 329 } 330 331 for (int ι=0, KdestinationStrmgs sized , ι++) { 332 String destinationString = (String) destinationStrings elementAt (i) , 333 StrmgTokenizer tokenizer = new StrmgTokenizer (destinationString ","), 334 335 if (tokenizer countTokenε ( ) '= 2) {

340 String hostname = tokenizer nextToken ( ) 341 String methodrame = tokenizer nextToken ( ) 342 343 // find out if the methodname actually point to one of the methods 344 // in the Agent 345 irt methodid = -1 346 for (int 3=0 ₃<launchInfo itsMethods length, ₃++) { 347 if (launchlnfo itsMethods [ 3 ] equals (methodname) ) { 348 methodid = 3 , 349 } 350 } 351 352 if (methodid == -1) { 353 System out println (StringResources I LEGAL_METHOD + methodname ) , 354 System out println (StnngResources USAGE) , 355 return , 356 } else { 357 launchlnfo itsltinerary addDestination (new Destination (hostname, methodid)); 358 } 359 } 360 361 // now that we have parsed the command ine and built up t e

Bootstrap. java_l Tuβ Nov 12 07:44:47 1996 9

362 // launchlnfo, we will actually attempt to launch the agent.

363 try {

364 launchAgent (launchlnfo) ;

365 } catch (LaunchException e) {

366 System. out. println (StringResources . LAUNCH_ERROR + ": " + e .getMessage ( ) ) ;

367 e.printStackTrace () ;

368 }

369 }

370 }

BootStrapClassLoader. java_l Tue Nov 12 07:44:47 1996 1

1 /* $Header: /com/meitca/hsl/zones jagents/bootstrap/BootStrapClassLoader . ava 3 11/11/96 5:13p Billp $

2 *

3 * Copyright 1995 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

8 *

9 * DESCRIPTION

10 * ClassLoader used in agent bootstrap process.

11 *

12 * $Log: /com/meitca/hsl/zonesjagentε/bootstrap/BootStrapClassLoader . Java $

13 *

14 * 3 11/11/96 5:13p Billp

15 * Made correction to company name.

16 *

17 * 2 9/28/96 6:56p Walsh

18 * Use AgentCodebase object to retrieve bytecodes.

19 *

20 * 1 8/29/96 5:21p Walsh

21 * intial version

22 *

23 */

24 package com . mei tca . hs l . zones j agents . bootstrap ;

25

26 import java.io.*;

27 import java.net.*;

28 import Java . rmi . Naming; 29

30 import com. meitca . hsl . zoneε jagents . conduit .* ;

31 import com. meitca . hεl . zones]agents . shared .* ;

32 import com. meitc .hεl . zoneεjagents . remoteloader .* ; 33

34

35 /**

36 * BootStrapClassLoader is used internally by the Bootstrap

37 * class to load agent related classes

38 * ©see Agent

39 * ©see Bootstrap

40 * ©see MobileCodebase

41 * ©author Thomas Walsh

42 */

43 public class BootStrapClassLoader extends ClassLoader {

44 /** An URL pointing to the cobease from which class files should be retrieved */

45 String itsHcmeCodebaseURL; 46

47 /** An object representing the home codebase of the agent */

BootStrapClassLoader. j va_l Tue Nov 12 07:44:47 1996 2

48 AgentCodebase itsHomeCodebase;

49^'

50 /** The mobile code base into which to load classes */

51 MobileCodebase itsMobileCodebase;

5

53 /**

54 * object which actually handles the dirty work or retrieving .class

55 * files for a given class.

56 */

57 ClassFileLoader itsClassFileLoader; 58

59

60 /**

61 * Constructs a BootStrapClassLoader.

62 * ©param url The directory from which this ClassLoader should

63 * retrieve .class files

64 */

65 public BootStrapClassLoader (String url) throws MalformedURLException { 66' itsHomeCodebaseURL = url;

67 itsHomeCodebase = new AgentCodebase (url) ;

68 itsMobileCodebase = null;

69 itsClassFileLoader = new ClassFileLoader () ;

70 }

71

72 /**

73 * Constructs a BootStrapClassLoader. When this consturctor is

74 * called, the ClassLoader realizes that their is an associtated

75 * MobileCodebase object. As .class files are read from disk,

76 * they are also written into the MobileCodebase. Once they are

77 * leaded into the MobileCodebase, they are ready to travel.

78 * ©param dir The directory from which this ClassLoader should

79 * retrieve .class files

80 * ©param codebase The associated MobileCodbaεe object

31 * "//

82 p,ublic B_o.o.tStrapClassLoader (String₌ url, MobileCodebase codebase) throws MalformedURLExcep_rtion {.

83 tthhiiss ((uurrll)) ;;

84 itsMobileCodebase = codebase;

⁸ 8⁵6 >

87 /**

88 * Load a class. The classes .class file must be in the directory

89 * that was specified in the constructor. If a MobileCodebase

90 * was specified in the constructor, the class will also be loaded

91 * into that codebase.

92 * ©param name The class name

93 * ©param resolve True if resolveClasε should be called

94 */

BootStrapClassLoader.java_l Tue Nov 12 07:44:47 1996 3

95 public Qlass loadAgentClaεs (String name, boolean resolve) throws ClassNotFoundException {

96

97 byte[] bytecodes = itsHomeCodebase .retrieveCode (name) ;

98

99 Class c = defineClass (bytecodes , 0 , bytecodes . length) ;

100 if (resolve )

101 resolveClass (c) ; 102

103 if (itsMobileCodebase != null)

104 itsMobileCodebase. storeCode (c .getNa e () , bytecodes); 105

106 return c ;

107 } 108

^"109 /**

110 * Load a class from the specified file. The file must be in the

111 * directory that was specified in the constructor. If a

112 * MobileCodebase was specified in the constructor, the class will

113 * also be loaded into that codebase.

114 * ©param name The class filename

115 * ©param resolve True if resolveClass should be called

116 */

117 //STABILITY: Integrate this method with loadAgentClass

118 public Clasε loadAgentClassFromFile (String fileName, boolean resolve)

119 throws FileNotFoundException, IOException, ClassNotFoundException , ClaεsFormatError { 120

121 File file = new File (itsHo eCodebaseURL, fileName);

122 long length = file . length( ) ;

123 FilelnputStream stream = new FilelnputStream (file) ;

124 byte data[] = new byte [ (int) length] ; 125

126 stream. read (data) ;

127 Class c = defineClass (data, 0, ( int) length) ;

128 if (resolve) {

129 resolveClass (c) ;

130 ) 131

132 i f ( i tsMobi leCodebase ! = nul l )

133 i tsMobi leCodebase . s toreCode ( c . getName ( ) , data ) ; 134 return c ;

135 }

136

137 /**

138 * The Java . lang .ClassLoader version of loadClass .

139 * First looks for a standard system class, and then looks for an

140 * agent class in the directory that was specified in the constructor.

141 * If the class is an Agent related class, then its bytecodes are

BootStrapClassLoader. j ava_l Tue Nov 12 07:44:47 1996 4

142 * loaded into the MobileCodebase

143 * ©param name The clasε name

144 * ©param resolve True if resolveClass should be called

145 */ /

146 protected Class loadClass (String name, boolean resolve) throws ClaεεNotFoundException {

147 try {

148 Claεε c = f indSyε emClass (name) ;

149 if (resolve) {

150 resolveClass (c) ;

151 }

152 return c ;

153 } catch (ClasεNotFoundException el) {

154 try {

155 return loadAgentClaεs (name, resolve);

156 } catch (Exception e2) {

157 throw new ClassNotFoundException ( "Could not load " + name) ;

158 )

159 }

160 )

161 )

FindFilePanel. java_l Tue Nov 12 07:44: 7 1996 1

1 /* $Header /com/mei tca/hsl/zones₃agent=;/bootstrap/FindFilePanel ]ava 5 11/11/96 5 13p Billp $

2

3 * Copyright 1996 Horizon Systems Laboratory

4 * Mitsubishi¹ Electric Infcrmation Technology Center America

5 * All r_ghts reserved

6 *

7 * CONFIDENTIAL AND PROPPIETAR PROPEPT> OF MITSUBISHI ELECTRIC ITA 8

9 * DESCRIPTION 30 * The FindF l(?Pan<=l if thp AgentLaunchWizard 11

12 * $Log com/meιtca/h"=;l/zones3agents/bootstrap/Fιnd^t:,ιlePanel ]ava $ 13

14 * 5 ll/ll/°6 5 13p BJ 11D

15 * Made correction to company name 16

17 * 4 10/0 /96 4 44p Wal<=;n

18 * Save name & lo^cation of last agent launched Restart Wizard pointing

19 * at same agent

20 *

21 * 3 9 / 10 / 96 11 46a Wal sh

22 * remove boαus imports that η avac cons iders il l egal

23 *

24 * 2 9/09/96 3 45p Walsh

25 * replace g₃ t MessageDialoσ w/ com meitca hsl util InfoDialog

26 *

27 * 1 8 /2 ° / 9 o 5 21 p Wa l =h

28 * mtial ve- ' on 29

3 0 * /

31 package com ∑oresjagents bootstrap 32

33 import ₃ava a*t *

34 import ₃ava 10 *

35 import g₃t Ut i 36

37 import com me_tca hεl utn Wizard

38 import com me.tea hεl util WizardPanel

39 import com meitca hsl util InfoDialoα 40

41 /

42 * the first panel of the AgentLaunchWizard This panel allows the user

43 * to specify the filename of the class file contaimnα the agent

44 * ©see Agent

45 * ©see AgentLaunchWizardPanel

46 * ©see AgentLaunchWizard

47 * ©author Thomas Wal^n

FindFilePanel. java_l Tue Nov 12 07:44:47 1996 2

48 */

49 public class FindFilePanel extends AgentLaunchWizardPanel {

50 /** The edit field */

51 TextField I tsFileBrowseField , 52

5₃ /** The "Brcwse " button */

54 Button itsFileBrowseButton, 55

56 /**

57 * Construct the FindFilePanel and all of its components

58 * Sparam wizard The wizard to which this panel belongs (needed by

59 * super)

60 * @param wiinfozard The AgentLaunchlnformation descπnging this

61 * agent launch (needed by super)

62 */

63 public FindFilePanel (Wizard wizard, AgentLaunchlnformation info) {

64 super (wizard, info);

65 buildPanel ( ) ,

66 } 67

68 /**

69 * Verify that the information entered into the panel is valid. Called

70 * after the "Next >" button is pressed 71

72 * The method validates the following things .

73 * 1) A class file name is specified

74 * 2) The file name ends with " class'

76 * 4) The file contains valid Java bytecodes

77 * 5) The file contains a class derived from Agent

78 * 6) An invocation skeleton is available

79 * Sreturrε true if the panel contains valid info, false if not

80 */

81 public boolean val idatePanel ( ) {

82 // we want to break the full filename up into the directory portion

83 // and the filename portion. Find the last occurrence of the

84 // directory seperator character

85 String fullName = ltsFileBrowseField getTextO,

86

87 // Verify that someone typed something into the edit control and that

// what they typed in ends with class

89 if (fullName. length () == 0) {

90 InfoDialog info = new InfoDialo ( itεWizard,

91 StringResources. AUNCH_ERROR_TITLE,

92 StringResources. NO_FILENAME) ;

93 ±nfo . setBackground (Color . lightGray) ;

94 info sho ( ) ;

FindFilePanel. java_l Tue Nov 12 07:44:47 1996

95 return false ;

96 )

97

98 if ('fullName endsWithC class")) {

99 IrfoDialog info = new InfoDialog ( ltsWizard,

100 StringResources LAUNCH_ERROR_TITLE,

101 StringResources ENDSWITH_CLASS) ,

102 lrfo setBackground (Color lightGray),

103 lrfo show() ,

104 return false

105 ) 106

107 itsAgentlnfo itsAgentDirectory = new String ('')

108 itsAgentlnfo itsAgentDirectory = fullName 109

110 for (int ι=fullName length()-l ι>=0, ι--) {

111 if (fullName charAt(ι) == File separatorChar ) {

112 itsAgentlnfo itsAgentDirectory = fullName εubstnngtO, l+l),

113 itsAgentlnfo itsAgentFile = fullName substring ( l+l , fullName length!) ) ,

134 break;

115 }

116 }

¹ 1¹1⁷8 // Now let the AgentClassInfoGatherer verify the existence of the file,

119 // tnat the file contains a valid Java Aαent and that the skeleton

120 // exists

121 Ty {

122 AgentClassInf Gatherer agentlnfoGatherer = new AgentClassInfoGatherer (

123 itsAgentlnfo i sAgentDirectory, itsAgentlnfo ItsAgentFile 124

125 itsAgentlnfo ltsM thods = agentlnfoGatherer getAgentMethods ( ) ,

126 return true,

127 ) catch (FileNotFoundExcep ion el) {

128 InfoDialog info = new InfoDialog ( l tshizard,

129 StringResources LAUNCH_ERROR_TITLE, 130 StringResources FILE_NOTFOUND) ,

134 } catch (IOException el) {

135 InfoDialog info = new InfoDialog ( 136 StringResources LAUNCH_ERROR_TITLE,

137 StringResources IOERROR) ,

138 info setBackground (Color lightGray),

139 mfo show( ) ,

140 return false;

141 } catch (ClassFormatError el) {

FindFilePanel. java_l Tue Nov 12 07:44:47 1996 4

142 InfoDialog info = new InfoDialog ( ltsWizard,

14₃ StringResources LAUNCH_ERROR_TITLE,

144 StringResources BAD_CLASS_FORMAT) ,

145 info setBackground (Color lightGray),

146 info show( ) ,

147 return false,

148 } catch (NotAgentException el) {

149 IrfoDialoq info = new InfoDialog ( ltsWizard,

150 StringResources LAUNCH_ERROR_TITLE,

151 StringResources NOT_AGENT) ,

152 info setBackground (Color lightGray),

153 info show( ) ,

154 return false,

155 ) catch (ClassNotFoundException el) {

156 InfoDialog info = new InfoDialog ( ltsWizard,

157 StringResources LAUNCH_ERROR_TITLE,

158 StringResources BAD_CLASS_FORMAT) ,

159 info setBackgroun (Color lightGray)

160 ii fo show( ) ,

161 return false,

162 } catch (NoAgentSkeletonException el) {

163 It foDialog info = new InfoDialog ( ltsWizard,

164 StringResources LAUNCH_ERROR_TITLE,

165 StringResources NO_SKELETON) ,

166 inro setBackground (Color lightGray),

167 info show( ) ,

168 return false,

169 }

170 ) 171

172 /**

173 * Builds the GUI Components for this panel

174 */

175 private void buιldPanel() {

176 setLavout (new GπdBagLayout ( ) ) , 177

178 Label labell = new Label (StringResources FF_TEXT1 , Label LEFT),

179 constrain (this, labell,

180 0, 0, 1, 1,

181 GridBagConstraints HORIZONTAL, GridBagConstraints NORTHWEST, 0 0,

182 0, 0, 0,0),

183

184 Label label2 = new Label (StringResources FF_TEXT2 , Label LEFT),

185 constrain ( his, label2,

186 0, 1, 1, 1,

187 GridBagConstraints HORIZONTAL, GridBagConstraints NORTHWEST, 0 0, 189 0, 0, 0, 0) ,

FindFilePanel. java_l Tue Nov 12 07:44:47 1996

189

190 Label label3 = new Label (StringResources .FF_TEXT3 , Label . LEFT) ;

191 constrain ( this , label3,

192 0, 2, 1, 1,

193 GridBagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 0.0, 0.0,

194 0,0,0,0);

195

196 Label label4 = new Label (StringResources .FF_TEXT4, Label. LEFT);

197 constrain (this, label4,

198 0, 3, 1, 1,

199 Gri BagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 0.0, 0.0,

200 0,0,0,0);

201

202 Panel browsePanel = new Panel ();

203 constrain (.this, browsePanel,

204 0, 4, 1, 1,

205 GridBagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 1.0, 1.0,

206 0,0,0,0);

207

208 browsePanel . setLayout (new GridBagLayout ( ) ) ; v..

209 Label findFileLabel= new Label (StringResources . FF_FIELD_J^βEL, Label .LEFT) ;

210 constrain (browsePanel , indFileLabel , γ

211 1, 0, 1, 1,

212 GridBagConstraints. NONE, GridBagConstraints . NORTHWEST, 0.0, 0.0,

213 0,0,0,0);

214

215 itsFileBrowseField = new TextField (25) ;

216 constrain (browsePanel , i tsFileBrowseField,

217 2, 0, 1, 1,

218 GridBagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 1.0, 1.0,

219 0,0,0,0);

220

221 itsFileBrowseButton = new Button (StringResources .FF_BROWSE_BUTTON) ;

222 constrain (browsePanel , itsFileBrowseButton,

223 3, 0, 1, 1,

224 GridBagConstraints .NONE, GridBagConstraints .NORTHWEST, 0.0, 0.0,

225 0,0,0,0);

226

227 }

228

229 /** Derived from Component .action */

230 public boolean action(Event event. Object what) {

231 if (event .target == itsFileBrowseButton) {

232 doBrowse ( ) ;

233 return true;

234 }

235 return false;

FindFilePanel. java_l Tue Nov 12 07:44:47 1996

236 }

237

238 /**

239 * Ca led in response to selecting the Panel s Browse button Brings up

240 * a Open File Dialog

241 */

242 private void doBrowse() {

243 FileDialor browse = new Fi leDialog (Uti 1 getFrame ( this) , StringResources BROWSE_DLG_TITLE)

244 bro e set^rιle( * class ) 245

246 -f (itsAgentlnfo itsAgentDirectory '= null) {

247 if (itsAgentlnfo ItsAgentDirectory length () '= 0) {

248 browse setDirectory ( itsAgentlnfo ItsAgentDirectory) 2^9 }

250 )

251

252 browse show()

253

254 Stπnq ullFileName - n°k Strmαt )

255

256 if (browse getDirectory ( ) = null) {

257 if (browse getDirectory ( ) length () '= 0) {

258 fullFileName = browse getDirectory ( )

259 )

260 ) 261

262 f (b owse getFιle() '= null) {

263 if (browse getFileO length!) '- 0) {

264 fullFileName = fullFileName + browse getFileO

265 )

266 ) 26-7

268 -f (fullFileName length () '= 0)

269 ltsFileBrowεeField setText ( fullFileName)

270 } 271

272 /**

273 * Initializes the Panel for display

274 */

275 public void displayPanel ( ) {

276 String fullFileName =

277

278 if (itsAgentlnfo ItsAgentDirectory '= null) {

279 if (itsAgentlnfo itsAgentDirectory lengthO '= 0) {

280 fullFileName = itsAgentlnfo itsAgentDirectory 281

282 if ('fullFileName endsWith (File separator)) {

FindFilePanel. java_l Tue Nov 12 07:44:47 1996 7

283 fullFileName += File separator,

284 >

285 }

286 }

287

288

289 if (itsAgentlnfo ItsAgentFile •= null) {

290 if (itsAgentlnfo ItsAgentFile length () '= 0) {

291 fullFileName += itsAgentlnfo itsAgentFile

292 )

293 } 294

295 if (fullFileName length () '= 0)

296 ltsFileBrowεeField setText ( fullFileName)

297 } 298

299 300 }

ItineraryGridDataModel. java_l Tue Nov 12 07:44:47 1996 1

1 /* $Header /co /mei tca/hεl/zones_jagents/bootstrap/I tineraryGridDataModel ₃ava 3 11/11/96 5 13p 2

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America

All rights reservec CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

9 * DESCRIPTION 10 * A Data Model class for use in conjunction with the Roque Wave 11 * Grig class 12 + 13 * $Log /com/mei tea /hsl/zones₃agents/bootstrap/ItmeraryGridDataModel java $ 14 _* 15 * 3 11/11/96 5 13p Billp 16 * Made correction to company name 17 * 18 * 2 9/04/96 12 36p Walsh 19 * Propogate changes to Destination terminology 20 * 21 * 1 8'29/96 5 21p Walsh 22 * mtial version 23 _* 24 */ 25 package com meitca hsl zones]agentε bootstrap 26 27 import com roguewave widgets *, 28 import com roguewave widget^ grid * 29 import ₃ava u _^l Vector, 30 import ₃ava util Enumeration 31 32 import com meitca hsl zoneε;agentε conduit Destination 33 import com meitca hεl zoneεiagents conduit Itinerary 34 35 r 36 * Implements a the necessary com rogue widgets grid * interfaces to 37 * support the display of a Grid object This class is tied to the 38 * Grid control on the ItineraryPanel of the AgentLaunchWizard The 39 * grid is used to specify the Itinerary of the Agent to launch 40 * Osee Itinerary 41 * @see ItineraryPanel 42 * Θsee AgentLaunchWizard

43 * øauthor Thomas Wal εh

44 * /

45 public class ItineraryGridDataModel extends SelectionGridModel {

46 /*^"* The rows displayed in the grid */

47 Vector ltsRows

ItineraryGridDataModel. ava_l Tue Nov 12 07:44:47 1996

48

49 /** The ItineraryPanel thiε object iε tied to. */

50 ItineraryPanel itspanel; 51

52 /**

5₃ * Construct a ItineraryGridDataModel

54 * gparam panel The I ineraryPanel this object is tied to

55 */

56 public ItineraryGridDataModel (ItineraryPanel panel) {

57 itsRows = new Vector () ;

58 itsPanel = panel;

59 } 60

61 /** derived from SelectionGridModel . fetchstrmg */

62 public String etchString ( int row, int column) {

63 try {

64 // vectors are zero based Grids are one based, so we need to

65 // subtract one

66 Destination aRow = (Destination) itsRows elementA (row-1) ;

67 switch (column) {

68 case 1 ^•

69 return aRow getDestinationHost ( ) ;

70 default-

71 return " " ,

72 }

73 } catch (ArraylndexOutOfBoundsException e) {

74 return " " ,

75 )

76 ) 77

78 /** de^rived from SelectionGr ldModel . fetchlnteqer */

79 public int fetchlnteger (int row, int column) {

80 try {

81 // vectors are zero based. Grids are one based, so we need to

82 // subtract one

83 Destination aRow = (Destina ion) itsRows elementAt (row-1) ;

84 switch (column) {

85 case 2 :

86 return aRow. getMethodID( ) + 1;

87 default ^•

88 return 0;

89 }

90 } catch (ArraylndexOutOfBoundsException e) {

91 return 0;

92 )

93 ) 94

ItineraryGridDataModel. java_l Tue Nov 12 07:44:47 1996 3

95 /** derived from SelectionGridModel update */

96 public boolean update (int row, mt column, String value) {

9₇ Destination aRow,

98

99 try { 100 // vectors are zero based Grids are one based so we need to 301 // subtract one

102 aRc = (Destination) itsRows elementAt (row-1 )

103 ) r-Ttch (Arra> IndexOutO BoundsExceotioπ e){

104 aRow = new Destination!)

105 ιt'^Do s insertElementAt (aRow row 1) 106

107 // a new destination has been added to the Itinerary Letε add

108 // a new blank row to the Grid εo that the user has space to type any

109 // more destinations

110 ltεPanel addRowf)

111 } 112

113 switch (column) {

114 case 1

115 aRow setDestinationHoε (value)

116 break

117 default

118 break

119 )

120 return true

121 } 122

123 /** derived from SelectionGridModel update */

124 public boolean upda^te (int row int column int value) { 126

127 try {

128 // are zero based Grids are one based, εo we need to

129 // subtract one

130 aRow = (Destination) itsRows elementAt (row-1 )

131 } catch (ArraylndexOutOfBoundsException e){

132 aRow = new Destination ( )

133 itsRows insertElementAt (aRow, row-1) 134

135 // a new destination has been added to the Itinerary Lets add

136 I I a new blank row to the Grid so that the user has space to type any

137 // more destinations

138 addRow()

139 } 140

141 εwitch (column) {

ItineraryGridDataModel. ava_l Tue Nov 12 07:44:47 1996 4

142 case 2

14₃ aRow setMethodID(value - 1) ,

144 break,

145 default ,

146 break

147 )

148 return true

149 } 150

151 /*

152 * Retreives the Itinerary which has been specifed by the user

153 */

154 public Itinerary get Itinerary ( ) {

155 Itinerary itinerary = new ItineraryO,

156 Enumeration enum = itsRows elements () 157

158 while (enum hasMoreElements ( ) ) {

159 Destination destination = (Destination) enum nextElement ( ) ,

160 itinerary addDes ination (destination)

161 }

162 return itinerary,

163 }

164 }

ItineraryPanel. java_l Tue Nov 12 07:44:47 1996 1

1 /* $Header /com/mei tca/hsl/zones_jagentε/bootstrap/ItineraryPanel java 3 11/11/96 5 13p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved 6

7 * CONFIDENTIAL AND PROPRIETARY PROPEPTY OF MITSUBISHI ELECTRIC ITA

8 *

9 * DESCRIPTION

10 * The ItineraryPanel of the AgentLaunchWizard

11 *

12 * $Log / com/meitca/hsl/zonesjagentε/bootεtrap/ItineraryPanel ava $

13 *

14 * 3 11/11/96 5 13p Billp

15 * Made correction to company name 16

17 * 2 9/10/96 11 46a Walεh

18 * remove boguε imports that javac considers illegal

19 *

20 * 1 8/29/96 5 21p Walεh

21 * mtial version

22 *

23 */

24 package com meitca hεl zoneεjagentε bootstrap

25 import java awt *

26 import java 10 *

27 import com roguewave wιdqet=; grid * 28

29 import com meitca hsl util Wizard

30 import com meitca hsl util WizardPanel 31

32

33 /**

34 * The third panel of the AqentLaunchWizard This panel allows the user

35 * to specify the Itinerary of the agent

36 * Ssee Itirerary

37 * @see AgentLaunchWizardPanel

38 * @see AgentLaunchWizard

47

ItineraryPanel . j ava_l Tue Nov 12 07 : 44 : 47 1996

48 /** _

49 * Construct the ItineraryPanel and all of its components

50 * øparam wizard The wizard to which this panel belongs (needed by

51 * super)

52 * @pararn wimfozard The AgentLaunchlnforma ion d°scnngιng this

5 * agent launch (needed by super)

54 */

55 public ItineraryPanel (Wizard wizard AgentLaunchlnformation info) (

56 super (wizard info)

57 buildPanelO

58 } 59

60 /**

61 * The W zard calls this method right before it is going to display

62 * the panel In thiε case the Panel needs to recreate the Grid

63 * so that the ChoiceColumn of the grid contains the names of the

64 * available methods of the currently selected Agent

65 */

66 public void dιsplay^Danel ( ) {

07 remove ( it Grid)

68

69 // Crate a new grid model

70 ltsDataModel = new ItineraryGridDataModel ( this)

71 // Crate a new Grid in εpreadεheed mode

72 ltεGrid = new Grid (Grid TABLE_MODE ltsDataModel ltsDataModel ltsDataModel ltsDataModel )

73 itsGrid getCel lPanel ( ) setVertLineColor (Color gray)

74 itsGrid getCellPanel ( ) setHorzLmeColor (Color gra )

75 itsGrid editable = true 76

77 // Set the grid column heading panel s attributes //

78 itsGrid setColumnheadmgPanel (new ColumnHeadingPanel ( ) )

79 itsGrid qetColumnhead gPanel ( ) setBackground (Color lightGray)

80 itsGrid getColumnHeadingPanel ( ) setForeground (Color black)

81 itsGrid getColumnhead gPanel () εetThreeDΞtyle (Grid THREED_RAISED)

82 itsGrid getColumnHeadingPanel ( ) setHorzLines ( true)

83 itsGrid getColumnHeadingPanel ( ) setTextL eε ( 1)

85 // Add a text field column to the grid //

86 TextFieldColumnAttribute coll

87 coll = new TextFieldColumnAttribute ( )

88 coll setTitle (StringResources DEST_COL_TITLE)

89 coll εetWιdth(150)

90 ( (TableColumnCollei-tion) itsGrid getColumnCol lection () ) add(coll)

91

92 ChoiceCo LumnAttribu e choiceColu n = new Choκ eColumriAt tribute ( )

93 choiceColumn setTi tie (StringResources ACTION_COL_TITLE)

94 choiceColumn εetWidth ( 150 )

Stinerary anel.java_l Tue Nov 12 07:44:47 1996 3

95 ((TableColumnCollection) itsGrid getColumnCollection ( ) ) add (choiceColumn)

96

97

98 // Set the grid to have 1 row //

99 (itsGrid getRowCollection ( ) ) εetRows(l),

100

101 constrain (thiε, itsGrid

102 0, 6, 1, 1,

103 GridBagConstraints BOTH, GridBagConstraints NORTHWEST, 1 0, 1 0,

104 0,0,0 0), 105

106

107 choiceColumn addltem(' ' ) ,

108 fordnt ι= 0, KitsAgentlnfo itsMethods length, ι++) {

109 choiceColumn addltem( itsAgentlnfo itsMethods [ l ]) ,

110 } 111

112 invalidated

113 validate))

114 } 115

116 /**

117 * Verify that the information entered into tne panel s valid Called

118 * after the Next >' button is pressed

119 * There is no actual verification necessary This method simply

120 * retirpveε the Itinerary from the data model and stuffε it into

121 * the AgentLaunchln o

122 * ^returns true if the panel contains valid info, false if not

123 */

124 public boolean val idatePanel ( ) {

125 itsAgentlnfo itsltinerary = l sDataModel getltinerary!),

126 return true

127 ) 128

129 /**

130 * Builds the GUI Components for this panel

131 */

132 private vo d buildPanelf) {

133 setLayout (new GridBagLayou ( ) )

134

135 Label labell = new Label (StringResources ITIN_TEXT1, Label LEFT),

136 constram(thιε, labell,

137 0, 0, 1, 1,

138 GridBagConstraints HORIZONTAL, GridBagConstraints NORTHWEST, 0 0,

139 0 0 0 0) 140

141 Label label2 = new Label (StringResources II1N_TEXT2 Label LEFT),

ItineraryPanel . java_l Tue Nov 12 07 : 44 : 47 1996 4

142 constrain ( this , label2 ,

143 0 , 1 , 1 , 1 ,

144 GridBagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 0.0, 0.0,

145 0,0,0,0); 146 147

148 Label label3 = new Label (StringResources . ITIN_TEXT3 , Label. LEFT);

149 constrain ( this, label3,

150 0, 2, 1, 1,

151 GridBagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 0.0, 0.0,

152 0,0,0,0); 153

154

155 Label label4 = new Label (StringResources . ITIN TEXT4 , Label. LEFT);

156 constrain (this, label4,

157 0, 3, 1, 1,

158 GridBagConstraints. HORIZONTAL, GridBagConstraints . NORTHWEST, 0.0, 0.0,

159 0,0,0,0); 160

161 Label label5 = new Label (StringResources . ITIN_TEXT5, Label. LEFT);

162 constrain (this, labelδ,

163 0, 4, 1, 1,

164 GridBagConstraints. HORIZONTAL, GridBagConstraints . ORTHWEST, 0.0, 0.0,

165 0,0,0,0); 166

167 Label labelδ = new Label (StringResources . ITIN_TEXT6, Label . LEFT) ;

168 constrain ( this , labelβ,

169 0, 5, 1, 1,

170 GridBagConstraints .HORIZONTAL, GridBagConstraints . ORTHWEST, 0.0, 0.0,

171 0,0,0,0); 172

173 // Crate a new grid model

174 itsDataModel= new ItineraryGridDataModel ( this) ;

175 // Crate a new Grid in spreadsheed mode.

176 itsGrid = new Grid (Grid. TABLE_MODE, itsDataModel , itsDataModel, itsDataModel , itsDataModel ) ;

177 itsGrid. getCellPanel () . setVertLineColor (Color .gray) ;

178 itsGrid. getCellPanel () . setHorzLineColor (Colo .gray) ;

179 itsGrid. editable = true;

180

181 // Set the grid column heading panel's attributes //

182 itsGri . setColumnHeadingPanel (new ColumnHeadingPanel ( ) ) ;

183 itsGrid. getColumnHeadingPanel ( ) . setBackground (Color . lightGray) ;

184 itsGrid. etColumnHeadingPanel ( ) . se Foregroun (Color .black) ;

185 itsGrid. getColumnHeadingPanel () , setThreeDStyle (Grid .THREED_RAISED) ;

186 itsGrid. getColumnHeadingPanel () . setHorzLines ( true) ,-

187 itsGrid. getColumnHeadingPanel () . setTextLines (1) ; 188

ItineraryPanel . java_l Tue Nov 12 07:44:47 1996

189 // Add a text field column to the grid // 190 TextFieldColumnAttribute coll, 191 coll = new TextFieldColumnAttribute () , 192 coll secTitle (StnngResources DE^T_COL_TITLE) 193 coll setWιdth(150) , 194 ((TableColumnCollection) itsGrid getColumnCol lection () ) add(coll), 195 196 ChoiceCclumnAttπbute choiceColumn = new ChoiceColumnAttribute ( ) 197 choiceColumn εetTi ie (StringResources ACTION_COL_TITLE) , 198 choiceColumn setW dth ( 150 ) , 199 ((TableColumnCollection) itsGrid getColumnCollection ( ) ) add (choiceColumn) , 200 201 202 // Set the grid to have 1 row // 203 (itsGrid getRowCσllection ( ) ) εetRowε(l) 204 205 cons tram ( this , itsGrid, 206 0, 6, 1, 1, 207 GridBagConctia ts BOTH GridBagConstraints NORTHWEST, 1 0, 1 0, 208 0,0,0,0),

209

210

211 }

212

213 /**

214 * called by the ItineraryGridDa aModel to signify that a new row should be

215 * added to the Gr d

216 */

217 protected void addRow() {

218 itsGrid getRowCollection ( ) εetRows ( l sGπd getRowCollect ion ( ) count()+l),

219 }

220 )

ItineraryPanel. java_l Tue Nov 12 07:44:47 1996 5

189 // Add a text field column to the grid //

190 TextFieldColumnAttribute coll,

191 coll = new TextFieldColumnAttribute ( )

192 coll setTιtle(StrιngResourceε DEST_COL_TITLE) ,

193 coll εetUιdth(150)

194 ((TableColumnCollection) itsGrid getColumnCollection ( ) ) add(coll), 195

196 ChoiceCclumnAttnbute choiceColumn = new ChoiceColumnAttribute ( ) ,

197 choiceColumn setTi ie (StringResources ACTION_COL_TITLE) ,

198 choiceColumn setWidth (150) ,

199 ((TableColumnCollection) itsGrid getColumnCollection () ) add (cnoiceColumn) , 200

201

202 // Set the grid to have 1 row //

203 (itsGrid getRowCollection ( ) ) setRows(l) 204

205 constrain (th s , itsGrid,

206 0, 6, 1, 1,

207 GridBagConstraints BOTH, GridBagConstraints NORTHWEST 1 0, 1 0,

₂08 0,0 0,0), 209 210

211 }

212

213 /**

214 * called by the ItineraryGridDataModel to signify that a new row should be

215 * added to the Grid

216 */

217 protected void adαRo ( ) {

218 itsGrid getRowCollection ( ) setRows ( itsGrid getRowCollection ( ) count ()+l),

219 }

220 }

ffoAgentSkeletonException.3'ava_l Tue Nov 12 07:44:48 1996 1

1 /* $Header: /com/meitca/hsl/zones jagents/bootstrap/NoAgentSkeletonException . java 2 11/11/96 5 : 13p Billp

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

6 *

CONFIDENTIAL. AMD PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Exception indicating that Agent invocation Skeleton is missing.

11 *

12 * $Log : /com/mei tca/hsl/zonesjagents/boots rap/NoAgentSkeletonException . java $ 13

14 * 2 11/11/96 5:13p Billp

15 * Made correction to company name.

16 *

17 * 1 8/29/96 5:21p Walsh

18 * intial version

19 *

20 */

21 package com. meitca . hsl . zonesjagents . bootstrap;

22

23 /**

24 * Exception indicates that the system could not locate the Agent

25 * method invocation skeleton. This skeleton is used by the conduit

26 * server to invoke the proper method on the Agent when it arrives

27 * at a destination. The skeleton is generated by the Agent Skeleton

28 * Generator.

29 * @see Agent

30 * @see AgentSkeleton

31 * Sauthor Thomas Walsh

32 */

33 public class NoAgentSkeletonException extends Exception {

34 public NoAgentSkeletonException ( ) { 35 super ( ) ;

36 }

37

38 public NoAgentSkeletonException (String s) {

39 super (s) ;

40 }

41 }

NotAgentException. java_l Tue Nov 12 07:44:48 1996 1

1 /* $Header /com/mei tca/hsl/zones₃agents/bootstrap/NotAgentExceptιon ₃ava 3 11/11/96 5 13p Billp

2 *

3 * Copyright 1996 Horizon Syεtems Laboratory

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8 *

9 * DESCRIPTION

10 * Exception indicating that a class File does not contain an Agent

11 *

12 * $Log /com/meιtca/hsl/zones₃agentε/bootεtrap/NotAqentExceptιon ₃ava $

13 *

14 * 3 11/11/96 5 13p Billp

15 * Made correction to company name 16

17 * 2 9/30/96 6 35p Walsh

18 * fix up javadoc comments 19

20 * 1 8/29/96 5 21p Walεh

21 * mtial version

22

23 */

24 package com meitca hsl zones₃agents bootstrap 25

26 /**

27 * Exception indicates the class File specified did not contain

28 * a Java clasε derived riom Agent

29 * @see Agent

30 * Oauthor Thomas

31 */

32 public class NotAgentException extends Exception {

33 public NotAgentException ( ) {

34 super ( )

35 ) 36

RelatedFilesPanel. java_l Tue Nov 12 07:44:48 1996 1

1 /* $Header /com/mei tca/hsl/zones_jagentε/bootstrap/RelatedFilesPanel ]ava 3 11/11/96 5 13p Billp $

2 *

3 * Copyright 1996 Horizon Systemε Laboratory

4 * Mitsubiεhi Electric Information Technology Center America

All rights reserved

6

7 * CONFIDENT!/'. AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8

9 * DESCRIPTION 10 * The RelatedFileεPanel or the AgentLauncnWizarα 11

12 * SLog 'com/meitca/hsl/zonesjagentε/bootεtrap/RelatedFilesPanel ₃ava $

13 *

14 * 3 11/11/96 5 13p Billp

15 * Made correction to company name

16 *

17 * 2 9/10/96 11 46a Walsh

18 * remove bogus imports that javac considers illegal

19 *

20 * 1 8/29/96 5 21p Walεh

21 * irtial version

22 *

23 */

24 package com meitca hεl zonesjagents bootstrap, 25

26 import java av,r * 27 import ]ava lo * 28

29 import com meiira hsl uti- Wizard,

30 import com meitca hsl util WizardPanel 31

32

33 /**

34 * The second panel of the AgentLaunchWizard This panel allows the uεer

35 * to specify the filenames of claεεes that should be sent with the agent

36 * @see Agent

37 * @εee AgentLaunchWizardPanel

38 * @see AgentLaunchWizard

39 * θauthor Thomas Walsh 40 */

41 public class RelateαFilesPanel extends AgentLaunchWizardPanel {

42 /** The list control form which the user selects files */

43 List itεRelatedClasseεList ,

44

45

46 /**

47 * Construct the FindFilePanel and all of its components

RelatedFilesPanel. java_l TUΘ NOV 12 07:44:48 1996 2

48 * @param wizard The wizard to which this panel belongs (needed by

49 * super)

50 * Θparam wunfozar The AgentLaunchlnf ormation deεcπngmg this

51 * agent launch ( needed by super)

52 V

53 public RelatedFilesPanel (Wizard wizard, AgentLaunchlnformation info) {

54 super (wizard, info)

55 buildPanel () ,

56 ) 57

58 /**

59 * The Wizard calls this method right before it is going to display

60 * the panel In this case, the Panel needs to fill the List

61 * with the names of all the class files in the same directory as

62 * the Agent

63 */

64 public void displa Panel ( ) {

65 File agentDir = new File ( itsAgentlnfo itsAgentDirectory)

66 Strιng[] files = agentDir listfnew ClasεFileFilter ( ) ) ,

67

68 ltsRelatedClassesList clear!)

69 for (mt 1=0, Kfiles length, ι+H {

70 if ('fιles[ι] equals ( itsAgentln o ItsAgentFile))

71 ltεRelatedClaεsesList addl tern ( files [ l ] )

72 } 73

74 )

75

76 /**

77 * Vei-fy that the information entered into the panel is valid Called

78 * after the Next >' button is pressed

79 * Thei e is no actual verification necessary This method simply

80 * ret-reves the list of classes and stuffs tnern into the

81 * AgentLaunchlnfo '

82 * ^returns true if the panel contains valid info, false if not

83 */

84 public boolean validatePanel ( ) {

85 itsAgentlnfo l tεRelatedClasseε = itsRelatedClaεsesList getSelectedltemε ( ) ,

86 return true;

87 }

89 /**

90 * Buildε the GUI Componentε for this panel

91 */

92 private void builαPanelf) {

93 setLayout (new GridBagLayou ( ) ) 94

RelatedFilesPanel. java_l Tue Nov 12 07:44:48 1996 3

95 Label labell = new Label (StringResources . RF TEXT1, Label .LEFT) ;

96 constrain (this, labell,

97 0, 0, 1, 1,

98 GridBagConstraints. HORIZONTAL, GridBagConstraints . NORTHWEST, 0.0, 0.0,

99 0,0,0,0) ;

100

101 Label label2 = new Label (StringResources . RF_TEXT2, Label . LEFT) ;

102 constrain (this, label2,

103 0, 1, 1, 1,

104 GridBagConstraints. HORIZONTAL, GridBagConstraints . ORTHWEST, 0.0, 0.0,

105 0,0,0,0); 106

107

108 Label label3 = new Label (StringResources . RF_TEXT3 , Label ."LEF ) ;

109 constrain (this, label3,

110 0, 2, 1, 1,

111 GridBagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 0.0, 0.0,

112 0,0,0,0); 113

114

115 Label label4 = new Label (StringResources . F_TEXT , Label . LEFT) ;

116 constrain (this, label4,

117 0, 3, 1, 1,

118 GridBagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 0.0, 0.0,

119 0,0,0,0); 120

121 Label labelδ = new Label (StringResources . RF_TEXT5, Label . LEFT) ;

122 constrain(this, label5,

123 0, 4, 1, 1,

124 GridBagConstraints. HORIZONTAL, GridBagConstraints .NORTHWEST, 0.0, 0.0,

125 0,0,0,0); 126

127 Label labelδ = new Label (StringResources . RF_TEXT6 , Label . LEFT) ;

128 constrain ( this , label6,

129 0, 5, 1, 1,

130 GridBagConstraints .HORIZONTAL, GridBagConstraints .NORTHWEST, 0.0, 0.0,

131 0,0,0,0); -i

132

133 itsRelatedClassesList = new List(7, true);

134 constrain(this, itsRelatedClassesList,

135 0, 6, 1, GridBagConstraints. REMAINDER, 136 GridBagConstraints. BOTH, GridBagConstraints . ORTHWEST, 1.0, 1.0,

137 0,0,0,0);

138 }

139 } 140 141 /**

RelatedFilesPanel. java_l Tue Nov 12 07:44:48 1996 4

142 * A FilenameFilter object than scans for file ending in .class

143

144 class ClassFileFil ter implements FilenameFilter {

145 public boolean accept (File dir, String name) {

146 return (name . endsWith (". class ")) ;

147 )

148 }

StringResourcas. java_l Tue Nov 12 07:44:48 1996 1

1 /* $Header /ccm/mei tca/nsl/zones_jagentε/bootstrap/StπngReεourceε ₃ava 7 11/11/96 5 13p Billp

2 *

3 * Copyright 1996 Horizon Syεtems Laboratory,

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved c *

6

7 * CONFIDENTIAL AND PROPRIETARY PPOPER I Ϋ OF MITSUBISHI ELECTRIC ITA 8 9 * DESCRIPTION

10 * The String fo the boot slap pacl-age

11

12 * $Log /com, meιtca/hs^"i /zoneεjagentε/bootstrap/StringResources java $

13

14 * 7 11/11/96 5 13p Billc

15 * Made correction to company name 16

17 * 6 10/07/96 4 44p Walsh

18 * Save name & location of laεt agent launched Restart Wizard pointing

19 * at εame agent

20 *

21 * 5 9/15/96 5 lip Walεh

22 * Fix spelling mistakes 23

24 * 4 9/09/96 5 59p Walsh

25 * Make constants final

26 *

27 * 3 9/05/96 6 37p Walεh

28 * Add some strirσ mn=-t?n' ^■=^■ associated with the c mimand line launch

29 * utility 30

31 * 2 9/04/96 12 36p Walεh

32 * Add launch error message 33

34 * 1 8/29/96 5 21p Walsh

35 * mtial version

36 *

37 */

42 // AgentLaunchWizard java

43 public static String WIZARD_TITLE = "Agent Launch Wizard' ,

44 public static String WIZARD_APPNAME = "AgentLaunchWizard",

45 public static String PROP_DESC = 'Properties file for Zones Agent Launch Wizard' 46

47 // FindFilePanel Java

StringResources. ava_l Tue Nov 12 07:44:48 1996

48 public static final String LAUNCH_ERROR_TITLE = "Launch Error"; 49 public static final String NO_FILENAME = "You must specify the filename of the .class file containing the nt. '

50 public static final String ENDSWITH_CLASS = "You must specify a file ending with .class

51 public static final String FF_TEXT1 = "This wizard will assist you in launching Agents";

52 public static final String FF TEXT2 = "Please select the .class file containing the ";

53 public static final String FF_TEXT3 = "agent you would like to launch.";

54 public static final String FF_TEXT4 = "

55 public static final String FF_FIELD_LABEL = "Class File: ";

56 public static final String FF_BROWSE_BUTTON = "Browse...";

57 public static final String BROWSE_DLG_TITLE = "Open Agent Class File";

58

59 //ItineraryPanel . j va

60 public static final String DEST_COL_TITLE = "Destination";

61 public static final String ACTION_COL_TITLE = "Action";

62 public static final String ITIN_TEXT1 = "An agent's itinerary specifies where an agent travels to and";

63 public static final String ITIN_TEXT2 = "what operations the agent performs as it travels. Please

64 public static final String ITIN_TEXT3 = "specify the itinerary below. You should enter the host- ";

65 public static final String ITIN_TEXT4 = "names of the machines you would like your agent to travel " ;

66 public static final String ITIN_TEXT5 = "to as well as the methods you would like called at each stop.";

67 public static final String ITIN_TEXT6 = "

68

69 // RelatedFilesPanel . java

70 public static final String RF_TEXT1 You may specify a list of classes which should be sent with";

71 public static final String RF_TEXT2 the Agent. These should be classes which the Agent is likely"

72 public static final String RF_TEXT3 to use while it is travelling. " ;

73 public static final String RF_TEXT4

74 public static final String RF_TEXT5 Please select any classes you would like sent with the agent."

75 public static final String RF_TEXT6

76

77 // Bootstrap . java

78 public static final String USAGE "Usage: bootstrap [-d hostname, method] [-f relatedfile . class] \n\t [ -h] a tfile. class" ;

79 public static final String ILLEGAL_OPTN = "bootstrap: illegal option -- ";

80 public static final String SYNTAX_ERROR = "bootstrap: syntax error --

81 public static final String ILLEGAL_AGENT = "bootstrap: Illegal agent file -- ";

82 public static final String NO_AGENT = "bootstrap: No agent specified";

83 public static final String AGENT_HELP = "\tThe agent files must be valid Java class file\n\tand must end w . class " ;

84 public static final String ILLEGAL_RELFILE = "bootstrap: Illegal related filename -- ";

85 public static final String RELFILE_HELP = "\tThe related files specified by the -f option\n\ tmust be valid va class files and must end\n\twith .class";

86 public static final String ILLEGAL_DEST = "bootstrap: Illegal destination specification --

87 public static final String ILLEGAL_METHOD = "bootstrap: Illegal method name --

88 public static final String NO_DEST = "bootstrap: You must specify at least destination";

89

90 // shared strings

StringResources. java_l Tue Nov 12 07:44:48 1996 3

91 public static final String FILE_NOTFOUND = "Could not find the file specified

92 public static final String IOERROR = "An error occurred while trying to access the file specified

93 public static final String BAD_CLASS_FORMAT = 'The file specified did not contain a valid Java cl

94 public static final String NOT_AGENT = "The file specified did not contain a Java Agent "

95 public static final String NO_SKELETON = Could not locate the Agent's skeleton ",

96 public static final String LAUNCH_ERROR = 'An error occurred while attempting to launch the Agent

97

98 }

AgentPackage . ava_l Tue Nov 12 07 : 45 : 01 1996 1

1 / _* S_Header ,'com/me ι tca/hε l / zoneε_j agen ts /conduιt /AgentPackage j ava 18 11 / 11 / 96 5 15p Bi l lp $

2 *

3 * Copyright 1996 Horizon Syεtems Laboratory,

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL AND ^DROPRIFTAPY PROPERTY OF MITSUBISHI ELECTPIC ITA 8

9 * DESCRIPTION

10 * Agent tran portation package object

11 *

12 * $Log /com/meitca/hεl/zonesjagents/conduit/AgentPackage Java $ 13

14 * 18 11/11/96 5 15p Billp

15 * Made correction to company name 16

17 * 17 10/28/96 6 31p Walsh

18 * Add more debugging info

19 *

20 * 16 10/24/96 5 15p Walεh

21 * add some cebuggiπg information related to memory usage

25

26 * 14 10/11/96 9 ^6a Wal-h

27 * fix compiler bug

28 *

29 * 13 10/10,96 6 02p Wnl-

30 * Add persistence support 31

32 * 12 9/30/96 7 06p Ualεh

33 * clean up javadoc comments 34

35 * 11 9/29/96 4 08p Walεh

36 * Allow Destination methods to be specified by name

37 * Give Agent access to AgentPackage information

38 *

39 * 10 9/11/96 12 24p Walsh

40 * remove uneeded import of CollaboratorAgent

41 *

42 * 9 9/09/96 4 59p Walsh

43 * Call Agent prepareForTransport, completedTransport methodε

44 *

45 * 8 8/23/96 3 58p Walεh

46 * Add support for ad-hoc method invocation 47

AgentPackage. java_l Tue Nov 12 07:45:01 1996 2

48 * 7 8/22/96 5-45p Walsh

49 * Move the custom marshalling of the agent into the AgentPackage class

54 * 5 8/09/^<!6 4 38p Walεh

55 * Setting up file headers

56 */ 57

58 package com meitca hsl zoneε agentε conduit, 59

60 import java.io * ;

61 import java net.*;

62 import java rmi server MarshalException 63

64

65 import com meitca hεl zones agents shared Agent,

66 import com. meitca hsl util *, 67

68

69 /**

70 * An AgentPackage contains an Agent, its MobileCodebase and

71 * its Itinera^ry The AgentPackage is passes between Condui tServers

72 * when the Agent travels

73 * @see Condui tServerlmpl

74 * Θauthor Thomaε Walεh

75 */

76 public claεε AgentPackage {

77 Agent itsAgent,

78 MobileCodebase ItsMobileCodebase,

79 Itinerary itsltinerary,

80 String l tεHomeCodebaεeURL,

81 int itsOID, 82

83 84

85 /**

86 * Con'.tructs an AgentPackage

87 * @param agent The Agent

88 * Θparam code The Agent's mobile codebaεe

89 * Θparam itinerary The Agents itinerary

90 * ^@param homeCodebasellRL The URL of the Agent 'ε codebase

91 */

92 public AgentPackage (Agent agent, Mobi eCodebase codebase,

93 Itineraiy itinerary, String homeCodebasellRL) {

94 Debug println ( "conduit memory", 3, "AgentPackage " + this + " created"),

AgentPackage. java_l Tue Nov 12 07:45:01 1996 3

95 itsAgent = agent,

96 itsMobileCodebase = codebase,

97 itsltinerary = itinerary,

98 itsHomeCodebaseURL = homeCodebaεeURL

99 ltsOID = 0

100 }

101

102 protected void finalize () thro s Throwable {

103 Debug println (' condui t memory 3 AgentPackage ' + this + ' finalized )

104 "-uper finalize))

105 ) 106

107 /** Retrieves the Agent from the package */

108 public Agent getAgen ( ) {

109 return itsAgent

110 ) 111

112 /** Retrieves the Agent s Mobile Codebaεe from the package */

113 public MobileCodebaεe getMobileCodebase ( ) {

114 return ItsMobileCodebase

115 }

116

117 /** Retrieves the Agent's itinerary from the package */

118 public Itinerary getltinerar ( ) {

119 return itsltinerary

120 ) 121

122 /** Retrieves the Agent ε codebase URL from the package */

123 public String getHomeCodebaseUR ( ) {

124 return I εHomeCodebaseURL

125 ) 126

127 /**

128 * Prepares the Agent package for network transmission This method

129 * performs the conversion of the Agent to a network transmission

130 * format This metiod also calls the Agent 'ε prepareForTransport

131 * method

132 */

133 public void prepareForTransport ( ) {

134 Debug println ( 'conduit ' 2, 'AgentPackage prepareForTransport called'),

1-^L3^J5^:3

136 '/ give the aαent a chance to do any work in preperation

137 // for transport

138 itsAgent prepareForTransport () ,

139 } 140

141 /**

AgentPackage. java_l Tue Nov 12 07:45:01 1996 4

142 * Restores the Agent package for network transmissionfrom its

143 * network transmission format. This method also calls the Agent's

144 * completedTransport method.

145 */

146 public void restoreFromTransportForm( ) {

147 Debug .println ( "condui t" , 2, "AgentPackage . restoreFromTransportForm called");

148

149 // give the agent a chance to do any work in preperation

150 // for arrival at destination

151 itsAgent . completedTransport ( ) ;

152 } 153

154 private void readObject (ObjectlnputStream stream)

155 throws IOException, ClassNotFoundException {

156 Debug .println (" condui " , 2, " AgentPackage . readObject called"); 157

158 itsMobileCodebase = (MobileCodebase) strea . readObject () ;

159 Debug .println ( "conduit " , 4, " read MobileCodebase: " + itsMobileCodebase); 160

161 itsltinerary = ( Itinerary) stream. readObject () ;

162 Debug .println ( "conduit " , 4, " read Itinerary: " + itsltinerary);

163

164 itsHomeCodebaseURL = (String) stream. readObject () ;

165 Debug .println ( "conduit" , 4, " read Codebase URL: " + itsHomeCodebaseURL); 166

167 // do the special deserialization of the Agent using the

168 // ConduitObjectlnputStream class

169 ConduitServerClassLoader ClassLoader = new ConduitServerClassLoader ( itsMobileCodebase, itsHomeCodeh eURL) ;

170

171 // unmarshal the agent, build the AgentPackage and then pass it along to receiveAgent

172 bytef] serializedAgent = (byte []) stream. readObject () ;

173 ByteArraylnputStream bytelnStream = new ByteArraylnputΞtream ( serializedAgent ) ;

174 ConduitObjectlnputStream marshallnput = new ConduitObjectInputStream(byteInStream, classLoaά ) ;

175

176 Debug. println ( "conduit" , 4, " about to read Agent");

177 itsAgent = (Agent )marshallnput . readObject () ;

178 Debug. println ( "conduit" , 4, " read Agent: " + itsAgent); 179

180 // Restore the Agents reference to its Package will be

181 // restored when the agent arrives at the Destination

182 itsAgent . setPackage (this) ,-

183 } 184

185 private void writeObject (ObjectOutputStream stream)

186 throws IOException {

AgentPackage. java_l Tue Nov 12 07:45:01 1996 5

187 Debug .println ( "conduit" , 2, "AgentPackage .writeObject called"); 188

189 stream. writeObject ( itsMobileCodebase) ;

190 stream. writeObject ( itsltinerary) ;

191 stream. writeObject ( itsHomeCodebaseURL) ;

192

193 // do the special deserialization of the Agent using the

194 // ConduitObjectOutputStream class 195

196 // null out the Agents pointer to the AgentPackage. We have to

197 // do this because Java object persistence does not support

198 // isomorphic persistence. Since the AgentPackage has a

199 // reference to the Agent and the Agent has a reference

200 // to the AgentPackage we have a circular reference.

201 // Without isomorphic persistence, this circular referece

202 // vould cause the object serialization code to go into an

203 // infinite loop The reference to itsPackage will be

204 // restored when the agent arrives at the Destination

205 itsAgent setPackage (null ) , 206

207 ByteArrayOutputStream byteOutStream = new ByteArrayOutputStream( ) ;

208 Condui tObj ectOutputStream marshalOutput = new ConduιtObjectOutputStream(byteOutStream) ;

210 // use object serialization to stream the agent to a byte array

211 marshalOutput .writeObject (itsAgent) ;

212 byte[] serializedAgent = byteOutStream toByteArray ( ) ; 213

214 // finally write the serialized agent to the original output stream

215 stream writeObject (serializedAgent ) ^■

216 } 217

218 /** Retrieves the AgentSkeleton object corresponding to the Agent. */

219 AgentSkeleton get AgentSkeleton ( ) throws ClassNotFoundException, InstantiationException, IllegalAccessExce {

220 String agentClassna e = itsAgent getClassO getNamef),

221 String skelClassname = agentClassname + "_Skel",

222 ConduitServerClassLoader classLoader = (ConduitServerClassLoader) itsAgent getClassO getClassLoade

223 if (classLoader '= null)

224 return (AgentSkeleton) ( classLoader loadClass (skelClassname) .newlnstance ()) ,

225 else

226 return (AgentSkeleton) (Class forName (skelClassname) newlnstance ()) ;

227 } 228

229 void setOID(int oid) {

230 itsOID = oid;

231 }

AgentPackage. java_l TUΘ NOV 12 07:45:01 1996 6

232

233 int getOIDO {

234 return itεOID;

235 )

236

AgentSkeleton. java_l Tue Nov 12 07:45:01 1996 1

1 /* SHeader /com/mei tca/hsl /zoneεjagents/conduit/AgentSkeleton java 3 11/11/96 5 15p Billp $

2 *

₃ * Copyright 1996 Horizon Systems Laboratory

4 * Mitsubishi Electric Information Technolog\ Center America

5 * All rights reserved

7 * CONFIDENTIAL ANC PROPRIETAPY PROPERTY 0" MITSUBISHI EijΞCTPIC ITA

8 *

9 * DESCRIPTION

10 * Aqent method invocation ^leleton interface

11

12 * $Log /com/meitca/hsl/zonesjagentε/conduit/AgentSkeleton java $

13

14 * 3 11/11/96 3 15p Billp

15 * Made correction to company name

16 * 3

17 * 2 ^: 8/29/96 5 15p Walεh

18 * Add getMethodε method

19 *

20 * 1 8/23/96 3 ^OD Wal^

21 * Initial versiorε

22 */

23 package com meitca hsl zonesjagents conduit

24

25 import com meitca hsl zoαeεnagents shared Agent

26

27 /**

28 * An interface ret me ι_ho 5 inv cation s)eletcn

29 * The skeleton make a call tr any method within

30 * the Agent At ruitime *-he ConduitServer looks ft the Agent ε Itinerary

31 * and determines ivhat method should be called at the current location The

32 * skeleton allo ε the Concuit Server to call the method

33 * @εee Agent

34 * @εee Condu i tServer

35 * øauthor Thorras Walsh

36 */

37 public interface AgentSkele^ton { 38

39 I * *

40 * Invokes a method on an agent

41 * Θparam agen^1- The agent whoεe method to invoke

42 * Θparam ι The method ID number of the method to invoke

43 V

44 public void invoke (Agent agent int i) thro ε II leqalAcceεεException

4 ^5

46 /**

47 * R triPv^<- a 1 I ^■- 1 f the agont methodε which c in tie invoked h\

AgentSkeleton. java_l Tue Nov 12 07:45:01 1996 2

48 * the skeleton.

49 */

50 public String[ ] getMethodε ( ) ;

51 52

AgentThread. ava_l TUΘ NOV 12 07:45:02 1996 1

1 /* $Header /com' eitca/hεl/zonesjagents/conduit/AgentThread java 4 11/11/96 5 15p Billp $

^Δ 2 *

3 * Copyright 19S6 Horizor Systemε Laboratory

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL ^ D PROPPIETAPY PROPERTY OF MITSUBISHI ELECTRIC ITA 8

9 * DESCRIPTION

10 * provides the thro^d m viich an Agent will executes

11 *

12 * $Log /com/π eitca/rsl/zones jagentε/conduit/AgentThread java $

13 *

14 * 4 11/11/96 5 15p Billp

15 * Made correctior to company name 16

17 * 3 10/29/96 5 ^">8p Wain

18 * Use ErrorLog cla^-ε to report errorε

19 *

20 * 2 10/28/96 6 31p Wa]-n

21 * Add more debugging info

22 *

23 * 1 10/25/96 5 02p Walsn

24 * Make AgentThread public

25

26 */

27 package com meitca ^l zone^iaqentε conαu_^t 28

29 import ava util * 30

31 import com meitca hεl zoneεjaαentε shared *

32 import com meitca h=l util * 33

34 /**

3 5 * A εubc laεs o f Ui^a Agen tThread provides the thread in vihich an Agent wi l l

36 * execute

37 * @εee Agent

38 * @εee ConduitServer

39 * Sauthor Thomas Walεh

40 */

41 public class AgentThread extends Thread {

42 AgentPackage itsPackage 43

44 /**

45 * Constructs an AgentThread

46 * Pparam aσentPackaqe The package containing the agent, its code and

47 * its itinerary

AgentThread. java_l Tue Nov 12 07 : 45 : 02 1996 2

48 */

49 public AgentThread (AgentPackage agentPackage) {

50 Debug println (" conduit memory', 3, "AgentThread " + this + " created"

51 itsPackage = agentPackage,

52 this start ()

⁵ 54³ '

55 protected void finalize () thro ε Throwable {

56 Debug pr int ] n (' condui t Memory 3 Aqentlhread ^ this + " finalized")

58 ) 59

60 / * *

61 * Retrieves a reference to the Agent which is executing within thiε

62 * AgentThread

63 */

64 public Agent getAgent() {

65 return itsPackage getAgent(),

66 )

67

68 /**

69 * Retrieves a reference to the AgentPackage contained within thiε

70 * AgentThread

71 */

72 public AgentPackage getAgentPackage ( ) (

73 return ιt=Package,

74 } 75

76 /**

77 * Begmε the Agent ε execution

78 */

79 public void rjn ( ) {

80 try {

81 ConduitServerlmpl getPerεiεtenceStore ( ) addToStore ( itsPackage)

82 Aσen Skeleton skel = itsPackage getAgentSkeleton ( ) ,

83 Des^tination current = itsPackage qetlt merar ( ) getCurrentLocation ( ) , 84

85 if ( .urrent getMethodID ( ) == Destination UNKNOWN_METHOD_ID) {

86 current convertNameToId ( skel ) ,

37

88 89 εk=l invoke ( ltεPackage getAgentj

90 current getMethodID ()) ,

91 ltεPackage getltinerary ( ) getCurrentLocation ( ) εetCompleted ( ) ,

92 ConduitServerlmpl getPerεiεtenceStore ( ) updateStore ( ltεPackage) ,

93 } catch (Exception error) {

94 ErrorLog println ( "condui AgentThread'

AgentThread. java_l Tue Nov 12 07:45:02 1996 3

95 ErrorLog.SEVERITY_ERROR,

96 "An error occurred while executing Agent:",

97 error) ;

98 } 99

100 ConduitServerlmpl .decrementAgentCounters ( ) ;

101

102 try {

103 // pass the agent along.

104 ConduitServerlmpl . sendPackage ( itsPackage) ;

105 } catch (NoSuchElementException done) {

106 Debug . println ( "conduit " , 1, "AgentThread . un : No more destinations for Agent " +

107 itsPackage .getAgent () .get? tIDO) ;

108 } catch (Exception error) {

109 ErrorLog .println ( "conduit .AgentThread" ,

110 ErrorLog.SEVERITY_ERROR,

111 "An error occurred while transporting Agent:",

112 error) ; 313 }

114

115 // remove the agent from the persistence store

116 ConduitServerlmpl . getPersistenceStore ( ) . removeFromStore ( itsPackage ) ;

117 118

ConduitObjectlnputStream. java_l Tue Nov 12 07:45:02 1996 1

1 /* $Header: /com/meitca/hsl/zones agents/conduit/ConduitObjectlnputStream. java 9 11/11/96 5:15p Billp $ 2

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Specialized Object InputStream used for agent deserialization

11

12 * $Log: /com/meitca/hsl/zonesjagents/conduit/Condui tObj ectlnputStream. java $

13

14 * 9 11/11/96 5:15p Billp

15 * Made correction to company name.

16 *

17 * 8 11/01/96 5:32p Walsh

18 * Modify debugging levels of debug output

19 *

20 * 7 10/21/96 4:26p Walsh

21 * Add debug logging

22 *

23 * 6 9/30/96 7:05p Walsh

24 * clean up javadoc comments 25

26 * 5 9/11/96 6:40p Walεh

27 * fix compiler error

28 *

29 * 4 9/11/96 6:33p Walsh

30 * derive from Marshal *Stream

31 *

32 * 3 8/22/96 2:19p Walsh

33 * Clean up code a little 34 35 * 2 8/13/96 5:09p Walsh

36 * Added comments & documentation. resolveClass now uses

37 * ConduitServerClassLoader

38 *

39 * 1 8/12/96 7 : 17p Walsh

40 * Initial versions

41 */

42 package com. eitca . hsl . zonesjagents . conduit ;

43

44 import java .10. InputStream;

45 import java . io . IOException;

46 import jav . io . StreamCorruptedExcep ion ;

47 import java . lang .ClassNotFoundException;

ConduitOb3ectOutputStream.3'ava_l TUΘ Nov 12 07:45:02 1996 1

1 /* $Header: /com/meitca/hsl/zonesjagents/conduit/ConduitObjectOutputStrea . java 7 11/11/96 5:15p Billp $

² 3 ^** Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA. 8

9 * DESCRIPTION

10 * Specialized MershallnputStream used for agent deserialization

11 *

12 * $Log: /com/meitca/hsl/zonesjagents/conduit/ConduitObjectOutputStream. java $ 13

14 * 7 11/11/96 5:15p Billp

15 * Made correction to company name. 16

17 * 6 11/01/96 5:32p Walsh

18 * Modify debugging levels of debug output

19 *

20 * 5 10/21/96 4:26p Walsh

21 * Add debug logging

22 *

23 * 4 9/30/96 7:06p Walsh

24 * clean up javadoc comments

25 *

26 * 3 9/11/96 6:33p Walsh

27 * derive from Marshal*Stream

28 *

29 * 2 8/22/96 2:19p Walεh

30 * Clean up code a little 31

32 * 1 8/12/96 7 : 17p Walsh

33 * Initial versions

34 */

35 package com. eitc . hsl . zonesjagents . conduit ; 36

37 import java . io . OutputStream;

38 import java . io . IOException ;

39 import java . io .StreamCorruptedException ;

40 import java . lang .ClassNotFoundException;

41 import java . rmi . server .MarshalOutputStream;

42

43 import com.meitca .hsl . util .* ; 44

45 public class ConduitObjectOutputStream

46 extends MarshalOutputStream { 47

ConduitObjectlnputStream. ava_l Tue Nov 12 07:45:02 1996 3

95 Debug .println ( "conduit . classload" , 3, "ConduitObjectlnputStream. resolveClass called for " + classr

) ;

96

97 return itsClassLoader . loadClass (classname) ;

98 }

99 }

ConduitObjectlnputStream. java_l Tue Nov 12 07:45:02 1996 2

48 import java rmi server MarshallnputStream

49 import ava net MalformedURLException

50 import java net URL,

51 import ava rmi server StubClassLoader oz 53 import com meitca hsl util *

54

55 /**

56 * A subclass of Obj ectlnpu Stream which is uεed to handle deserialization

57 * of Agent objects ConduitObjectlnputStream overrides the

58 * ObjectlnputStream resolveClass method As the deserialization process

59 * encounterε object contained within the agent, resolveClass is called for

60 * each unique class resolveClass makes use of a ConduitServerClaεεLoader

61 * object to search the agents MobileCodebase for class bytecodes

62 * Ssee Agent

63 * Θsee ConduitServerClassLoader

64 * @see Ob ectlnputStream

65 * @see MobileCodebase

66 * ©author Thomas Walsh

67

68 class ConduitObjectlnputStream

69 extends MarshallnputStream {

70

71 /** Class loader object uεed for deserializing an agent */

72 ConduitServerClassLoader itsClassLoader 73

74 /**

75 * Constructs a ConduitObjectlnputStream

76 * Θparam is Tie InputS^reara containing the Agent object

77 * @param classLoader A ConduitServerClaεεLoader capable of loading

78 * classes from the Agent's MobileCodebase

79 */

80 public ConduitOb ectlnputStreamdnputStream is ConduitServerClassLoader classLoader)

81 thrcws IOException, StreamCorruptedException {

82 super (is)

87 /**

88 * Resolves a fully qualified class name to a Class object resolveClass uses a

89 * ConduitServerClasεLoader to actually perform the class loading

90 * @param classname Tne classes fully qualified claεε name

91 */

92 protected Claεε resolveClass (String classname)

93 throws IOException, ClassNotFoundException ( 94

ConduitObjectOutputStream. va_l Tue Nov 12 07:45:02 1996

48 public ConduitObjectOutputStrea (OutputStream is)

49 throws IOException {

50 super (is ) ;

51 } 52

53

54 protected vcid annotateClass (Class cl) throws IOException {

55 Debug .println ( "condui . classload" , 3, "ConduitObjectOutputStream. annotateClass called for " + cl);

56 }

57 }

ConduitServer. java_l Tue Nov 12 07:45:02 1996 1

1 /* $Header /com/mei tca/hεl/zoneεjagentε/condui t/ConduitServer java 9 11/11/96 5 15p Billp $ 2

3 * Copyright 1996 Horizon Syεtemε Laboratory,

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA 8 9 * DESCRIPTION

10 * Conduit Server distributed interface

11

12 * $Log /com/meitca/hsl/zonesjagentε/conduit/ConduitServer java $

13

14 * 9 11/11/96 5-15p Billp

15 * Made correction to company name 16

17 * 8 9/30/96 7 06p Walsh

18 * clean up javadoc comments 19

20 * 7 8/27/96 3 51p Walsh

23 * 6 8/22/96 5 45p Walεh

24 * Move the custom marshallinq of the agent into the AgentPackage class 25

26 * 5 8/19/96 5 26p Walsh

27 * Add support for remote class loading 28

29 * 4 8/13/96 11 47a Walεn

30 * Add documentation t< conm°ntε Change signature of receivePackage

31 * method 32

33 * 3 8/12/96 7 15D Walsh

34 * ConduitServer no» performs Marεhalling 35

36 * 2 8/09/96 4 38p Walεh

37 * Setting up file headers

38 */ 39 40 package com meitca hεl zoneε agents conduit,

41

42 import java rmi Remote,

43 import java rmi RemcteException

ConduitServer. java_l Tue Nov 12 07:45:02 1996 2

49 /**

50 * ConduitServer is an RMI distributed interface It provides some RMI glue

51 * that allows conduit εerverε to communicate ConduitServer lε implemented

52 * by the ConduitServerlmpl class Conduit servers provide for Agent travel

53 * and execution

54 * @εee ConαuitServerlmpl

55 * ©author Thomas Walsn

56 */

57 publ i c i n t- prf acp Condu i Sei 'ei ^py '" Pn - R^piri i te { 58

59 /**

60 * Receive an Agent from the previous conduit server in its Itinerary

61 * Sparam aPackage The package containing the agents ltε mobile

62 * codebaεe and it itinerary If a communication error occurs

65 public void receivePackaqe (AgentPackaqe aPackage)

65 throws Re oteEyception

ConduitServerClassLoader. java_l Tue Nov 12 07:45:02 1996 1

1 /* $Header: /com/meitca/hsl/zonesjagents/conduit/ConduitServerClassLoader . java 12 11/11/96 5:15p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Conduit Server ClassLoader subclass

11 *

12 * $Log: /com/meitca/hsl/zonesjagents/conduit/ConduitServerClassLoader . java $

13 *

14 * 12 11/11/96 5 : 15p Billp

15 * Made correction to company name.

16 *

17 * 11 11/01/96 5:32p Walsh

18 * Modify debugging levels of debug output

19 *

20 * 10 10/24/96 5:15p Walsh

21 * add some debugging information related to memory usage.

22 *

23 * 9 10/21/96 4:26p Walsh

24 * Add debug logging

25 *

26 * 8 9/30/96 7:06p Walsh

27 * clean up javadoc comments

28 *

29 * 7 9/28/96 6:37p Walsh

30 * use the AgentCodebase class to retrieve bytecodes 31

32 * 6 8/22/96 5:42p Walsh

33 * Cache Classes we define 34

35 * 5 8/19/96 5:25p Walsh

36

37 * 4 8/13/96 5:09p Walsh

38 * Added comments & documentation. loadClass now looks in MobileCodebase.

39 *

40 * 3 8/13/96 11:19a Walsh

41 * remove obsolete loadMobileClasses method

43 * 2 8/09/96 4:38p Walsh

44 * Setting up file headers

45 */ 46

47 package com. eitca .hsl . zonesjagents . conduit ;

ConduitServerClassLoader. j ava_l Tue Nov 12 07:45:02 1996 2

48

49 import java rmi Naming

50 import java io * ,

51 import java net *,

52 import java util *

53

54 import com meitca hsl zone<-jaqentε shared *

55 import com meitca h<=-l util * 56

57 I * *

58 * A specialized ClassLoaαer object used by the conduct server to manage agent

59 * creation, deserialization, snd sub-object creation ConduitServerClassLoader

60 * eytends the base system class loading behavior by allowing for classes to be

61 * loaded from the MobileCodebase of an Agent For example, an Agent object might

62 * be created on one particular server on a network When it lε created, ltε

63 * bytecodeε are added to the MobileCodebase The aqent nov. travels to a new

64 * εerver The bytecodes for thiε particular agent have not been installed on the

65 * new server Under normal circumstances when the object deserialization code

66 * attmeptε to reconstruct the agent a ClaεεNotFoundException would reεult εince

67 * the agents code ones net exist anywhere on the new server

68 * ConduitServerClassLoader allowε the Java virtual machine to look for an Agentε

69 * code in the Mobi 1 "Codebase vhich allows Agent object to travel and pull their

70 * code with them

71 * @see Agent

72 * Θsee ConduitServer

73 * Θsee MobileCodebase

74 * Θsee ClaεεLoader

75 * @author Thomaε Walεh

76 */

77 public clasε Condui ServerClassLoader

78 extends Cla sLoader { 79

80 /** The MobileCodebaεe corresponding to the Aqent being managed */

81 MobileCodebase l tsMob_ l°Codebase 82

83 /** An URL back to the coebase of this agent on its home machine */

84 AgentCodebase itsHomeCodebase 85

86 /**

87 * A hashtable containing the Clasε objectε we have already

88 * defined during the εeπalizat ion process

89 */

90 Hashtable 1 tsPrevιous lγDef medClasεeε

91

92 /**

93 * Constructs a ConduitServerClassLoader

94 * ^@param codebase The MobileCodebase corresponding to the

ConduitServerClassLoader. va_l Tue Nov 12 07:45-02 1996 3

95 * Agent being managed

96 * @param homeCodebaεeURL An URL back to the codebaεe of this o * agent on its home machine

98 * θexceptirn Malfo ι=dURI Exception if the URL pasεesd in aε the

99 * homeCodebaseURL parameter is invalid

104 1 t'-Mobi leCodebase - codeoase

105 ltεHomeCodebaεe = new AgentCodebase (homeCodebaseURL)

106 ltεPreviouslvDef medClasses = new Hashtable ()

107 } 108

109 protected void finalize () throws Throwable {

110 Debug println ( -onduit memory 3 ConduitServerClassLoader + this + finalized )

111 εuper fmaliz )

118 * @pararn na e Fully qualified name of the class to be loaded (le <b>

119 * java lang String </b>)

120 */

121 public Class loadClass ( String name)

122 throws ClassNotFoundException {

123 return loadClass (name Tue)

124 ) 125

126 /**

127 * Loads a class Inherited from ClassLoader First check on the local

128 * system and then loo^s in the Mobi eCodebase

129 * ^@param name Fully qualified name of the claεs to be loaded (le

130 * java lang String

131 * @param boolean value indicating wether or not the claεs

132 * should be resolved via the ClasεLoader resolveClass method

133 */

134 protected Class loadClass (String name boolean resolve)

135 threws ClassNot^FoundException (

136

137 Debug prιrtln( conduit claεsload 2 ConduitServerClaεsLoader loadClaεε called for +

38 Debug pπrtl conduit classload 2 reεolve is + reεolve)

139

140 // firεt check the cache to see if we have encountered this class

141 // ' ofore Not= A ClassLoader object should always do something

ConduitServerClassLoader. ava_l Tue Nov 12 07:45:02 1996 4

142 // like this In order for Java ' ε type checking to work properly,

143 // everytime a loadClaεs lε called for a particular claεs name, the 344 // EXACT SAME Claεε object muεt be returned

145 Clasε cache = ( Claεε ) itsPre louεlyDef niedClaεεes get (name),

146 if (cache ' = null) {

147 Debug println (' condui t claεεload' 3, "Claεε found in cache"),

148 return cache

149 } 150

151 try {

152 // first check this system

153 Class c = indSystemClass (name) ,

154 Debug print In ( "condui t claεεload", 3, "Clasε found on system"),

155 if (r»solve) {

156 resolveClass (c)

157 )

158 return c,

159 } catch (ClasεNotFoundException e) {

160 // wasn't found on thiε syεtem Check the MobileCodebaεe

161 b\ te [ ] ytecodeε = i sMobi eCodebase getCode (name) ,

162

163 if (bytecodes '= null) (

164 Debug println (' condui t claεεload", 3, 'Clasε found in MoblleCodebaεe" ) , 165

166 // bytecodes for the claεε were found in the MobileCodebase

167 // Try tr- define a clasε from them

168 Claεε c - def meClass (HΛ t erodes , 0, bytecodes length)

169 if [resolve! (

170 ιe"ιlve( lar- ( - ) 171

172 // εtore this claεε in the cache

173 l tεPreviouεlyDef medClass°ε put (name, c),

174 )

175 return c

176 ) elεe {

177 Debug println ( "condui t clasεload', 3, "Looking in home codebase'),

178 return loadClasεFromHomeCodebaεe (name, resolve),

179

180 }

181 }

182

183

184 /**

185 * Loads a clasε using the remote claεε loader

186 * Θparam name Fully qualified name of the class to be loaded tie

187 * ava lang String

188 * Θparam reεolve boolean value indicating ΛPther or not the class

ConduitServerClassLoader. java_l Tue Nov 12 07:45:02 1996 5

189 * should be resolved via the ClassLoader . resolveClass method

190 */

191 protected Class loadClassFromHomeCodebase (String name, boolean resolve)

192 throws ClassNotFoundException {

193

194 Debug . pr int ln ( " condui t . class load " , 2 , " Condu itServerClassLoader . loadClassFromHomeCodebase called f *

" + name) ;

195 Debug .println (" condui t . classload" , 2, "resolve is " + resolve);

196

197 byte [ ] bytecodes = itsHomeCodebase . retrieveCode (name) ;

198

199 // bytecodes for the class were found in at remote location.

200 // store them in the MobileCodebase for future reference

201 itsMobileCodebase . storeCode (name, bytecodes); 202

203

204 // Try to define a class from them.

205 Class c = defineClass (bytecodes , 0, bytecodes . length) ;

206 if (resolve) {

207 resolveClass (c) ; 208

209 // store this class in the cache

210 itsPreviouslyDef inedClasses . put (name, c);

211 }

212 return c ;

213 }

214 }

ConduitServerlmpl. java_l Tue Nov 12 07:45:02 1996 1

1 /* {Header /com/meitca/hsl/zones_jagentε/conduit/ConduitServerlmpl java 23 11/11/96 5-15p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved 6

7 * CONFIDENTIAL AMD PROPRIETARY PROPERTY OF MITSUBISHI ELECTPIC ITA

8 *

9 * DESCRIPTION

10 * Conduit Server implementation

11

12 * $Log /com eitca/hsl /z^neε jagentε/condui t /Condui tServerlmpl Java $

13

14 * 23 11/11/96 5 15p Billp

15 * Made correction to company name

16 *

17 * 22 10/30/96 2 52p Walεh

18 * Allow Debug and ErrorLog settings to be set m propertieε file

19 *

20 * 21 10/29/96 5-28p Walsn

21 * Use ErrorLog class to repoit errors 22

23 * 20 10/28/96 6 31p Walsh

24 * Add more debugg.ng info 25

26 * 19 10/25/96 5 02p Walsn

27 * Make AgentThread public Mcve to own source file

28 *

29 * 18 10/24/96 5 1 _P Wal-n

30 * add some debugσinα information related to memory uracie 31

32 * 17 10/23/96 2 2?p Walsh

33 * add more Debug println ε 34

35 * 16 10/21/96 4 26p Walsn

36 * Add debug logging

37

38 * 15 10/11/96 2 2 Op Walεh

39 * remove reεtarted agents from perεiεtence εtore

40

41 * 14 10/10/96 6 02p Walεh

42 * Add persiεtence εucport 3 *

44 * 13 9/29/96 4 08p Walεh

45 * Allow Deεtination methods to be specified by name

46 * Give Agent access to AgentPackage information 47

ConduitServerlmpl. java_l Tue Nov 12 07 : 45 : 0₂ 1996 2

48 * 12 9/09/96 6 : 02p Walεh

49 * make conεtant final

50

51 * 11 9/04/96 12:32p Walsh

52 * Centralize manipultation of Condui erver ' s RMI URL.

53 * Move test εecurity mnnayer out of this file.

54

55 * 10 8/30/96 3 : 3p Walεh

56 * null out itsPackage (in AgentThrea . run ) to try to nudge the garbage

57 * collector 58

59 * 9 8/23/96 3 : 58p Walεh

60 * Add support for ad-hoc method invocation 61

62 * 8 8/22/96 6:36p Walεh

63 * Add static reference to the one Condui Server that exists. 64

65 * 7 8/22/96 5:45p Walεh

66 * Move the custom marshalling of the agent into the AgentPackage claεε 67

68 * 6 8/19/96 5:26p Walsh

69 * Add support for remote class loading 70

71 * 5 8/13/96 5 : 12p Walεh

72 * Changed signature of receivePackage . Changed marshalling,

73 * un-marεhall ing code to arhεal only Agent and not entire AgentPackage 74

75 * 4 8/13/96 10:35a Walεh

76 * Add εome comments and documentation

77 *

78 * 3 8/12/96 7 : 16p Walεh

79 * ConduitServer now performs Marshalling

80

81 * 2 8/09/96 4:38p Walεh

82 * Setting up file headers

83 */

84 package com. meitc . hsl . zoneε jagents . condui t ;

85

86 import java . rmi . server .UnicastRemoteServer ;

87 import java . rmi . RemoteExcept ion ;

88 import java . rmi .Namin ;

89 import java . rmi .NotBoundException;

90 import java.net.*;

91 import java.io.*;

92 import java. util.*; 93

94 import co .mei tea . hεl . zones agents . shared .* ;

ConduitServerlmpl. java_l Tue Nov 12 07:45:02 1996 3

95 import com meitca hsl util *,

96 import com meitca hεl zonesjaαentε εecurity InsecurityManager, 97

98 /**

99 * An RMI diεtribtted object which provides for Agent travel and execution

100 * ConduitServerlmpl implements th<= ConduitServer mterfa r> ConduitServer

101 * is an RMI distributed interface ConduitServerlmpl is responεible for

102 * receiving incoming agents, providing for execution of aqents, and for

103 * transmitting agents to other d°εt natιonε

104 * @see Agent

105 * @εee ConduitServer

106 * øauthor Thomas Walεh

107 */

108 public class Condui tServei Impl

109 extends UnicaεtRemoteServer

110 implements ConduitServer { 111

112 /**

113 * The conduit server _s a Sentinel object There hill only be one of

114 * them running within a given Java vertual machine The εtatic member

115 * theServer is a pointer to that one Condui Serverlmpl object

116 */

117 εtatic Condui tServerInol theServer,

118

119 /** The conduit servers name */

120 String itsName, 121

122 /** The conduit server proterties fil *_/

123 JASPropert ies i ts Proper t ies , 124

125 /** An object representing the εerverε perεiεtence store */

126 Condui tServerPersiεtenceStore l tεPer=" lεtenceStore 127

128 /** String constants */

129 /**The name to which a conduit server is bound in the RMI Registry */

130 static final String RMI_NAME = "ConduitServer",

131 static final String PROP_DEΞC= 'Properties File for Conduit Server", 132 133

134 I *

135 * The following member variables store some statistical information

136 * about the performan e of the Conduit Server

137 */

138 /** The date and time when this Conduit Server waε εtarted */

139 Date l tsStartTime ; 140

141 /** The number of Aqents currently in the εytem V

ConduitServerlmpl . j ava_l Tue Nov 12 07 : 45 : 02 1996 4 42 lonq i tεCurrentAgen tCount ,

143

144 /**

145 * The total number of Agents to travel through the system

146 * since startup

147 */

148 long itsTotalAgentCount ,

149

150 /**

151 * The largest number of Agent to be in tho εystem at any one time

152 */

153 long itsPeakAgentCount ;

154 155 156

157 /**

158 * Constructs a conduit server

159 * Oparam name The servers name

160 * Oexc^ppticn F°r^t^DException If an error occurs setting up network

161 * communicat ions

162 */

163 public ConduitServerlmpl (String name) throwε RemoteException {

164 ltεName = new String (name)

165 theServer = thiε,

166

167 // intialize the counterε

168 ItsTotalAgentCount = 0,

169 l tεCurrentAgentCount = 0,

170 itsPeakAαentCount = 0 71

17? try {

173 itsProperties = new JASProperties (RMI_NAME,

174 JASPropertieε SER 175 PROP_DESC,

176 falεe) ,

183 // Construct an empty Properties object

184 itsProper ies = new JASProperties () ,

185 }

186

187 // Set up the debug and error logging facilities usinq the

188 // Conduit ^IVPΓ specific properties

ConduitServerlmpl. java_l Tue Nov 12 07:45:02 1996 5

189 Debug . enable ( itsProperties ) ;

190 ErrorLog . initialize ( itsProperties) ; 191

192 itsPersistenceStore = new ConduitServerPersistenceStore ( ) ;

193 } 194 195

196 /**

197 * Send the Agent on to the next conduit server in its Itinerary.

198 * Θparam agentPackage The Agent Package containing the Agent.

199 * ^exception NoSuchElementException If the agent has completed its

200 * Itinerary.

201 * øexception RemoteException If an error occurs communicating with

202 * the next server.

203 * Sexception NotBoundException If the server name indicated as the

204 * next destination in the Itinerary cannot be found on the

205 * network.

206 */

207 public static void sendPackage (AgentPackage agentPackage)

208 throws NoSuchElementException, IOException,

209 RemoteException, NotBoundException{

210

211 // retrieve a remote reference to the next destination

212 ConduitServer nextConduit = (ConduitServer ) Naming . lookup (

213 buildRmiURL (agentPackage .getltinerary ( ) . nextDestination ( ) . getDestinationHost

) ) )

214

215 agentPackage .prepareForTransport ( ) ;

216

217 // pass the agent along

218 nextConduit . receivePackage (agentPackage) ;

219 } 220

221

222 /**

223 * Receive an Agent from the previous conduit server in its Itinerary.

224 * ^@param agentData A stream of bytes containing the serialized

225 * agent .

226 * dparam codebase The agents MobileCodebase

227 * Spararn itinerary The agents Itinerary

228 * ^exception RemoteException If an error occurs communicating with

229 * the prior server.

230 */

231 public void receivePackage (AgentPackage agentPackage)

232 throws RemoteException {

233 Debug. println( "conduit" , 2, "ConduitServerlmpl . receivePackage called");

234 agentPackage. restoreFromTransportFormO ;

ConduitServerlmpl. ava_l Tue Nov 12 07:45:02 1996 6

235 Debug println ( "condui t " , 1, "Agent " + agentPackage getAgent ( ) getAgentlDO +" has arrived"⁾;

236

237 lr crementAgentCounters ( )

238

239 AgentThread neωThread = new AgentThread (agentPackage) ,

240 } 241

242 static public void restartAgent (AgentPackage agentPackage) {

243 Debug println (' condui t " , 1, "Restarting Agent ' + agentPackage getAgent() getAgentlDO), 244

245 lπcrementAgentCounters ( )

246

247 try {

248 if (agentPackage getltinerary ( ) getCurrentLocation ( ) hasCompleted () ) {

249 Debug println ( "conduit " , 1, "\tAgent had completed execution on this Conduit Servei

250 Debug println (' conduit " , 1, Agent to next Destination"), 251

252 decrementAgentCounters ( ) ,

253 sendPackage (agentPackage) , 254

255 // remove the agent from the persistence store

256 getPersistenceStore ( ) removeFromStore (agentPackage) ,

257 } elεe {

258 Debug println! ' conduit" , 1, "\tAgent had not completed execution on this Conduit Se er") ,

259 Debug pr intin (" condui t " , 1, ' \ tRestarting execution"),

260 AgentThread newThread = new AgentThread (agentPackage) ,

261 }

262 } catch (Exception e) {

263 ErrorLog println (' conduit ConduitServerlmpl",

264 ErrorLog SEVERITY_ERROR,

265 "An error occurred while restarting agent ",

266 e) ,

267 } 268

269 }

272 * REtrieves a property from the Conduit Server

273 * ^βparam key The name of the propery to retrieve

274 * ^@param def A default value which will be returned if

275 * the property cannot be found

276 * Oreturn the propery value (a string)

277 */

278 public static String getProperty (String key. String def) {

279 return theServer itsProperties getProperty (key, def),

ConduitServerlmpl. java_l Tue Nov 12 07:45:02 1996 7

280 }

281

282 /**

283 * Returns the conduit εerverε name

284 * Sexception RemσteE> ception If any network error occurs

288 } 289 290

291 /**

292 * This method is used internally to build a full RMI URL for a conduit

293 * server on the given host

294 */

295 protected static String buildRmiURL (String hostname) {

296 return new StnngC'rmi //' + hostname + /' + RMI_NAME) ,

297 }

300 /**

301 * Returns a refernece to the conduit εerverε persistence store

302 */

303 public static ConduitServerPersiεtenceStore getPersiεtenceStore ( ) {

304 return theServer itsPersistenceStore,

305 ) 306

307 /**

308 * Returns the ^ta' up tune I tins conduit servei

309 */

310 public static Date getStartupTime ( ) {

311 return theServer ltεStartTime

312 } 313

314 /**

315 * Returns the uptime of this conduit server (in milliseconds)

316 */

317 public static long getUpTimeO {

318 return (System currentTimeMilliε ( ) - theServer ltsStartTime getTimeO),

319 }

322 * Returns the total number of agents to pass through this

323 * Conduit Server since it was started

324 */

325 public static long getTotalAgentCount ( ) {

326 return theServer i sTotalAgentCount

ConduitServerlmpl. java_l Tue Nov 12 07:45:02 1996

327 ) 328

329 / _{* *}

330 * Returns the number of agents currently executing

331 * in this Conduit Serv°r

332 */

333 public static long getCurrentAgentCount ( ) {

334 return theServer i sCurrentAgentCount

335 } 336

337 /**

338 * Returns the maximum number of agents to be executing

339 * at any ore time in tiiε Conduit Server

340 */

341 public static long getPeakAgentCount ( ) {

342 return theServer itsPeaKAgentCount ,

343 } 344

345

346 /**

347 *

348 */

349 public static synchronized void incrementAgentCounters ( ) {

350 if (theServer '= null) {

351 theServsr ιtsTotalAgentCount++ ,

352 theServer ιtεCurrentAgentCount++

353 if (theServer ltsCurrentAgentCount > theServer itsPeakAgentCount)

354 theServer l tεPeakAgentCount = theServer ltsCurrentAgentCount,

355 }

356 } 357

358 /**

359

360 */

368 * Performs εerver εtartup taskε

369 */

370 void εtartupO (

371 ltsPersistenceStore reεtorePerεiεtedObjects ( ) ,

372

373 // Monitor memory if conduit memory facility is εet to

ConduitServerlmpl. java_l Tue Nov 12 07:45:02 1996 9

374 // debug level 4

375 if (Debug enabled ( "conduit memory watch", 4)) { 76 MemoryWatch watch = new MemoryWatch ( ) ,

377 )

378

379 ltεStartTime = new Dated,

380 ) 381

382 /**

383 * A simple bootεtrap rfnich brings the conduit server into existence,

384 * registers it name with the RMI naming service and begins listening

385 * for Agent requeεtε The main routine allows ConduitServerlmpl to

386 * be intiated from the command line via the java command

387 */

388 public static void main (String args [ ] ) {

389 // Create and install the security manager

390 //System εetSecurityManager (new StubSecurityManager))),

391 System setSecur i tyManager (new InsecurityManager!) )

392

393 try {

394 // construct the εerver and register it with the RMI Naming service

395 Debug print In ( "-ondui " , 1, "Create an Conduit Server");

396 String rl = bui ldRmiURL ( InetAddress getLocalHos ( ) ge HostName ( ) ) , 397

398 Condui tServerlmol server = new Condui tServerlmpl (url ) , 399

400 Debug println (' conduit " , 1, "Bind it to name " + RMI_NAME) ,

401 Kamnq rebmd (RMI_NAMF server) 402

403 server tartupO

404 Debug print In (' condui t , 1, "Conduit Server ready )

405 ) catch (Exception e) {

406 ErrorLog print In (' condui t mam", ErrorLog SEVERITY_FATAL,

407 'an exception occurred during startup-", e) ,

408 )

409 }

410 }

_ConduitServerPersistenceStore.java_l Tue Nov 12 07:45:02 1996 1

1 /* $Header: /com/meitca/hsl/zonesjagents/conduit/ConduitServerPersistenceStore . java 6 11/11/96 5:15p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved.

6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Conduit Server persistence Store

11 *

12 * $Log: /com/mei tca/hsl /zonesjagents/condui t/ConduitServerPersistenceStore . java $ 13

14 * 6 11/11/96 5:15p Billp

15 * Made correction to company name. 16

17 * 5 10/29/96 5:29p Walsh

18 * Use ErrorLog class to report errors

19 *

20 * 4 10/21/96 4:26p Walsh

21 * Add debug logging

22 *

23 * 3 10/21/96 11:38a Walsh

24 * mirror change in Persistence API 25

26 * 2 10/18/96 10:58a Walsh

27 * synch with change to findObject API 28

29 * 1 10/10/96 6:01p Walsh

30 * initial version 31

32 */

33 package com. meitca .hsl . zonesjagents . condui t ; 34

35 import java . io . File ;

36 import java.util.*,- 37

44 * @see ConduitServerlmpl

45 * βauthor Thomas Walsh

46 */

47 class ConduitServerPersistenceStore {

ConduitServerPersistenceStore. java_l Tue Nov 12 07:45:02 1996

48 // String constants representing the propery names of

49 // two properties of interest

50 private static final String ENABLE_PERSISTENCE = " condui t . persistence . Enable " ;

51 private static final String PERSISTENCE_FILE = "conduit . persistence . FileName" ;

52 private static final String DEFAULT_FILENAME = "persist . store" ;

53

54 /** The PersistentStoreManager object used to manager the persistence store */

55 Persisten StoreManager itsStore;

56

57

58 * Constructs the PersistenceStore . Persistence will be enabled only

59 * if the conduit . persistence . Enable Property is set to "true". The

60 * PersistenceStore will be stored in the file named in the

61 * conduit .persistence . FileName property. If this Property is not set,

62 * the store will be placed in the file " zones . home/Agent/persist . store"

63 * only

64 */

65 ConduitServerPersistenceStore ( ) {

66 if (new Boolean (ConduitServerlmpl . getProperty (ENABLE_PERSISTENCE, " false ")) . booleanValue () ) {

67 Debug .println ( "conduit .persistence" , 1, "Persistence enabled.");

68

69 String filename = ConduitServerlmpl . getProperty (PERSISTENCE_FILE, " " ) ;

70 Debug . rintln ( "conduit .persistence" , 3, " condui . persistence . FileName property set to " + f ename) ;

71

72 if (filename. length () == 0) {

73 filename = AgentConstants .AGENT_DIR + DEFAULT_FILENAME;

74 }

75

76 try {

77 // construct the PersistentStoreManager

78 Debug . println ( "conduit .persistence" , 2, "Persistence filename is " + filename);

79 itsStore = new PersistentStoreManager ( filename) ;

80 } catch (PersistentStoreException e) {

81 ErrorLog. print In ( "conduit .Persistence" , ErrorLog . SEVERITY_ERROR,

82 "An error occurred constructing the persiste ce store e) ;

83 ErrorLog .println ( "conduit .Persistence" , ErrorLog . SEVERITY_WARNI G,

84 "Continuing without persistence.");

85

86 // null out the itsStore reference. We will continue

87 // executing with persistence disabled

88 itsStore null;

89

90

91 } else {

92 // null out the itsStore reference. This will

ConduitServerPersistenceStore. java_l Tue Nov 12 07:45:02 1996

93 // disable persistence

94 itsStore = null;

95 } 96

97 }

98

99 /**

100 * Adds an AgentPackage to the persistence store.

101 * Θparam aPackage The package to add.

102 */

103 void addToStore (AgentPackage aPackage) {

104 if (itsStore != null) {

105 if (aPackage. getOIDO == 0) {

106 Debug .println ( "conduit .persistence" , 3, "Adding agent to persistence store: " + aPc. age) ;

107

108 try {

109 int oid = itsStore . insertObject (aPackage) ;

110 Debug .println ( "conduit .persistence" , 4, "Agent's oid is: ". + oid);

111 aPackage. setOID(oid) ;

112 } catch (PersistentStoreDuplicateObjectException el) {

113 try {

114 Debug . println ( "conduit .persistence " , 4, "Agent already in store try g update" )

115 int oid = itsStore . findObject (aPackage^') ;

116

117 if (oid != PersistentStoreManager . INVALID_OID) {

118 Debug .println ( "conduit .persistence" , 4, "Agent found in sto oid : + oid) ;

119 itsStore .updateObject (oid, aPackage) ;

120 aPackage . setOID (oid) ;

121 } else {

122 ErrorLog .println ( "conduit .Persistence" , ErrorLog . SEVERITY_E

OR,

123 "An error occurred adding agent " + aPackag getAgent ( ) .getAgentID( ) +

124 " to the persistence store.");

125

126 ErrorLog .println ( "conduit . Persistence" , ErrorLog . SEVERITY_E OR,

127 "PersistentStoreManager . findObject returned ull even though " +

128 "PersistentStoreManager . insertObject threw

129 "PersistentStoreDuplicateObjectException . " )

130

131 ErrorLog. rintIn ( "conduit . Persistence" , ErrorLog . SEVERITY_W

ConduitServerPersistenceStore. java l Tue Nov 12 07:45:02 1996

NING,

132 'Continuing without persistence "),

133

134 // null out the itsStore reference We will continue

135 // executing with persistence disabled

136 itsStore = null ,

137 }

138 } catch (PersistentStoreException e2) {

139 ErrorLog println (' conduit Persistence", ErrorLog SEVERITY_ERROR,

140 "An error occurred adding agent " + aPackage getAgentO getAgentlDO +

141 ¹ to the persistence store ", e2),

142

143 ErrorLog println (' condui t Persistence" ErrorLog SEVERITY_WAR ING,

144 "Continuing without persistence "),

145

146 // null out the itsStore reference We will continue

147 // executing with persistence disabled

148 itsStore = null,

149 }

150 catch (PersistentStoreException e3) {

151 ErrorLog pr intin (' condui t Persistence'¹, ErrorLog SEVERITY_ERROR,

152 'An error occurred adding agent " + aPackage getAgent

() getAgentlDO

153 to the persistence store ' , e3 )

154

155 ErrorLog println (' conduit Persistence", ErrorLog SEVERITY_WARNING,

156 Continuing without persistence "), 157

158 // null out the itsStore reference We will continue

159 // executing with persistence disabled

160 itsStore = null,

161

162 }

163 }

164 }

165 166

167 * Updates an AgentPackage in the persistence store

168 * Θparam aPackage The package to add

169 */

170 void updateStore (AgentPackage aPackage ) (

171 if ( itsStore ' = nul l ) {

172 Debug println ( "conduit persistence", 3, "Updating agent in persistence store " + aPackage),

173 Debug pVmtln ( "conduit persistence", 3, "Agent's old is ^• " + aPackage getOIDO), 174

175 try {

ConduitServerPersistenceStore. java_l Tue Nov 12 07:45:02 1996

176 itsStore updateObject (aPackage getOIDO, aPackage),

177 } catch (PersistentStoreException e2) {

178 ErrorLog println ( "conduit Persistence", ErrorLog SEVERITY_ERROR,

179 "An error occurred updating agent " + aPackage getAgent() g

AgentID () +

180 " in the persistence store ", e2 ) ,

181

182 '-"rrorLog println ( "condui t Persistence', ErrorLog SEVERITY_WARNING,

183 "Continuing without persistence "),

184

185 // null out the itsStore reference We will continue

186 // executing with persistence disabled

187 itsStore = null,

188

189

190

191 }

192

193 /**

194 * Removes an AgentPackage to the persistence store

195 * Θparam aPackage The package to remove

196 */

197 void removeFromStore (Ager tPackage aPackage) {

198 if (itsStore '= null) {

199 Debug print In (' condui t persistence", 3, 'Removing agent from persistence store " + aPackag

200 Debug println ( conduit persistence", 3, 'Agent's oid is " + aPackage getOIDO),

201

202 try {

203 itsStore deleteObject (aPackage getOIDO),

204 } catch (PersistentStoreException e) {

205 ErrorLog println ( "conduit Persistence", ErrorLog SEVERITY_ERROR,

206 "An error occurred removing agent " + aPackage getAgent () g

AgertlDO +

207 ' from the persistence store ' , e) ,

208

209 ErrorLog println ( "conduit Persistence", ErrorLog SEVERITY_WARNI G,

210 'Continuing without persistence "),

211

212 I I null out the itsStore reference We will continue

213 // executing with persistence disabled

214 itsStore = null,

215

216

217 }

218

219

ConduitServerPersistenceStore. j va_l Tue Nov 12 07:45:02 1996 6

220 * Restores ail Agents m the Persistence Store and

221 * passes them into the ConduitServerlmpl restartAgent method

222 * so that they are restarted

223 */

224 void restorePersistedObj ects () {

225 if (itsStore '= null) {

226 Debug println (' conduit persistence", 3, "Restoring all persisted Agents"), 227 228 Enumeration enum = itsStore getOIDs ( ) ,

229

230 while (enum hasMoreElements ( ) ) {

231 Ob ectID objectID = (ObjectID) enum nextElement () ,

232 int oid = objectID getOIDO, 233

234 Debug println ( "conduit persistence", 4, 'Restoring Agent Old is " + oid);

235

236 if (oid '= 0) {

237 try {

238 AgentPackage aPackage = (AgentPackage) itsStore fetchObject (oid) ;

239 Debug println ( "conduit persistence", 4, "Agent Package is " + aPac age) ,

240 aPackage setOID(oιd) ,

241 ConduitServerlmpl restartAgent (aPackage) ,

242 } catch (PersistentStoreException e) {

243 ErrorLog println ( "conduit Persistence", ErrorLog SEVERITY_ERROR,

244 "An error occurred restoring persisted Agent ", e),

245

246 ErrorLog println (' condui t Persistence', ErrorLog SEVERITY_WARNING,

247 'Continuing without persistence "), 248

249 // null out the itsStore reference We continue

250 // executing with persistence disabled

251 itsStore = null,

252 }

253 } 254

255 }

256 }

257 }

258 }

Destination. java_l Tue Nov 12 07:45:03 1996 1

1 /* $Header /com/meitca/hεl/zoies_jagents/conduit/Destination ava 7 11/11/96 5 15p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

⁶ *

7 * CONFIDENTIAL ANE =R0P^1ETAP^V PROPERTY OP MITSUBISHI ELECTRIC ITA

8

9 * DESCRIPTION

10 * An agents destination Contains RMI UPL of conduit server and

11 * method id of method to irvo e at that location

12 *

13 * $Log /com/ite_^tca /h= i/zonesjagentε/conduit/Deεtmation java $ 14

15 * 7 11/11/96 5 15p Billp

16 * Made correction to company rame 17

18 * 6 10/10/96 6 02p Walεh

19 * Add persistence εuoport 20

21 * 5 9/30/96 ^"" CSp Walεh

22 * clean up javadoc co mεntε

23 *

24 * 4 9/29/96 4 C3p Walεh

25 * Allow Destmatior methods to oe εpecifieα by name informatio

28 * 3 9/04/96 II 31p Walsh

29 * Destination now holds orlv n hostname of the ConduitServer not the

30 * entire RMI URL 31

32 * 2 8/29/96 5 16p Jalεh

33 * add default cons'ructor and εet* methods 34

35 * 1 8/23/96 3 50p Walsh

36 * Initial versions

37 */

38 package com meitca hs¹ zonesjag≤ntε conduit

39

40 import com meitca hεl zonesjagents conduit InvalidMetbodNameExcept ion

41

42 /**

43 * An object representing a Destination in an Agents Itinerary The

44 * Destination is ccmposed of tΛic partε <br>

45 * <ol>

46 * <iι>the nostname of the conduit server in which to travel

47 * <lι> An .dentifer indicating the method of the agent to call

Destination. java_l Tue Nov 12 07:45:03 1996 2

48 * at that ConduitServer This identifier can either be an

49 * number representing a (zero based) ID of the method or the

50 * name of the method in the form of a String

51 * </ol>

52 * @see Agent

53 * @see ConduitServer

54 * Θsee Itinerary

55 * Θauthor Thomas Walsh

56 */

57 public class Destination implemsrts Cloneable {

58 εtatic final int UINKNOWNJ_METHOD_ID = -1, 59

60 /** The hostname of the Conduit Server in which to travel */

61 String itεr-ostName , 62

63 /** The method ID number of the method to invoke */

64 int itsMethodID, 65

66 /** The name of the metiod to invoke */

67 String itsKethodName ,

68

69 /**

70 * A boolean indicating wether execution at this destination

71 * has completed

72 */

73 boolean itεFaεCompleted, 74

75 /**

76 * Constructs a Destination object

77 * @param hostname The hostname of the conduit server in which to

78 * travel

79 * βparam methodNa e The name of tne method to invoke

80 */

81 public Destmatior (String hostname, String methodName) {

82 lts ostName = hostname,

83 ItsMethodID =

84 itεMethodNaire = methodName;

85 it shasCompleted = false;

86 } 87

90 * Constructs a Destination object This constructor is uεed

91 * internally to constrict a Destination

92 * @param hostname The hostname of the conduit εerver in which to

93 * travel

94 * dparam method The method ID number of the method to invoke

Destination. j ava_l Tue Nov 12 07:45:03 1996 3

95 */

96 public Destination (Stri i hostname, int method) { I itsKoεtName = hostname;

98 itsMethodID = mathod;

99 itsMethodName = null;

100 itsKasCompleted = falεe;

101 } 102

103 /**

104 * Construct" an »mpty ^",°εtmatιon object

105 */

106 public Destination ( ) {

107 itεhostName = new String!"");

108 itsMethodID = UNKNOWN_METHOD_ID; 109 itsKethodName = null,

110 itsKasCompleted = false,

111 } 112

113 /**

114 * Retrieve? the hof.i? <=■ of the conduit server in which to travel

115 */

116 public String getDeεtmationHcεt ( ) { 111 return itsHostName;

118 }

119

120 /**

121 * Retπeveε the method ID number of the method to invoke

122 */

123 public int getMethodID ( ) {

124 return itεrethc≤ID,

125 } 126

127 /**

128 * Setε the U^L of th= -onduit server in which to travel

129 */

130 public void εetDest nationKos (String hostname) {

131 itεhostName = hostname,

132 } 133

134 /**

135 * Sets the method ID nimber of the method to invoke

140 } 141

Destination. java_l Tue Nov 12 07:45:03 1996 4

142 /**

143 * Retπeveε the raet-.o name of the method to invoke

144 */

145 public String getMetnod ame ( ) {

146 return itsMethodName,

147 } 148

149 /**

150 * Makes a clone of the Destination object

151 */

152 public Destination clor sDestination ( ) {

153 Destination cone = neiv Destination ( )

154 clore ltsHcεtNa e = ltsHoεtName

155 clone ltsMetno≤ID = itsMethodID ,

156 clore itsMetnodName = itsMethodName,

157 re u n clc-e

158 } 159

160 /**

161 * Se*-s the internal state of the Destination to

162 * incicate that exe^cution has been completed

163 * /

164 void εetCompletedO {

165 itsKasCompleted = true,

166 } 167

168 /**

169 * Checks the interⁿal ^tate of the Destination to

170 * see if execut.c neε been completed

171 */

172 boolean hasCompleted ⁽ ) {

173 return ltεtπaεComDleted

174 } 175

176 /** Uεed internally to convert a method name into a method id */

177 protected void COΓN ertNameToId (AgentSkeleton εkel)

178 throws InvalidMethodNameException {

179

180 if (itεMethodName == null) {

181 throw new InvalidMethodNameException ( "No name εpecified for destination"),

182 } 183

184 String [ ] methoαε = ske l getMethods ( ) ,

185 f or ( int 1=0 , Kmethods length ; 1++ ) {

186 if (itsMethodName equalε (methodε [ 1 ]) ) {

187 ItsMethodID = 1,

188 ltsbethodName = null

Destination. va_l Tue Nov 12 07:45:03 1996 5

189 return;

190 }

191 }

192 throw new InvalidMethodNameException ( "Method name " + itsMethodName + "does not match any methods o agent") ;

193 }

194 }

InvalidMethodNameException. java_l Tue Nov 12 07:45:03 1996 1

1 /* SHeader: /ccm/meitca/h= 1/zonesjagents/conduit/InvalidMethodNameException . java 3 11/11/96 5;15p Billp S

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved. 6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Exception indicating that Method Name speicifed in a Destination

11 * is not a valid name 12

13 * $Log : /com/meitca/hsl/zonesjagents/conduit/Invalid ethodNameException . java $ 14

15 * 3 11/11/96 5:15p Billp

16 * Made correction to company name.

17 *

18 * 2 9/30/96 7:06p Walεh

19 * clean up javadoc comments

20 *

21 * 1 9/29/96 4:C7p Walsh

22 * initial version

23 *

24 */

25 package com. meitca .hsl . zonesjagents . conduit ;

26

27 /**

28 * An exception which indicates that the method name that was specified

29 * in a Destination was not the name of a method of the agent which

30 * is travelling.

31 * @see Agent

32 * @see AgentSkeleton

33 * @author Thomas Walsh

34 */

35 public class InvalidMethodNameException extends Exception {

36 public InvalidMethodNameException ( ) {

37 super () ;

38 }

39

40 public InvalidMethodNameException (String s) {

41 super (s) ;

42 }

43 }

Itinerary. j va_l Tue Nov 12 07:45:03 1996 1

1 /* $Header /com/meitca/hsl/ronesjagents/conduit/Itinerary java 5 11/11/96 5 15p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL AND OR0PF^T-riRY PROPERTY CF MITSUBISHI ELECTRIC ITA 8 9 * DESCRIPTION

10 * Agent itinerary object

11 *

12 * $Log /com/mextca =-ι zones jagents/conduit/Itmerary java $

13 *

14 * 5 11/11/96 5 15D Billo

15 * Made correction to co oa" name

16 *

17 * 4 9/29/96 4 08o walsh

18 * Allow Destination et^oαε to be soecified by name

19 * Give Agent access to ^Λc-~_^Dackage information

20 *

21 * 3 8/23/96 3 58p Walεh

22 * Add εupoort for ad c τ^-^od invocation

23 *

24 * 2 8/09/96 4 38p Wal=h

25 * Setting _UD file ^=>ad-<-_s

26 */

27 package com meitca hsl 28

29 import ava util * 30

31 /**

32 * An object represen^ting a^r Agent s Itinerary The Itinerary

33 * indicated WHERE an agent srould travel and indicated Ϊ'HAT

34 * the Agent should do at eacn stoo

35 * @see Agent

36 * @see ConcuitServer

37 * @see Destination 38 * Sauthor Thomas Walεh

39 */

40 public clasε Itinerary {

41 Vector ltεDestinations 42 int ltεCurrentStop

4 ⁴³4 /**

45 * Construc t " an I t ] lerary obj ec t 46 * /

47 publ i c I t inerary ) )

Itinerary. java_l Tue Nov 12 07:45:03 1996 2

48 ltsDest at ons = new Vector ()

49 ltsCurrent top = -1

50 }

51

52 /**

53 * Adds a nsi dest.ration to the end of the Ageⁿts Itinerary

54 * (?param deεt.-ation The new dest-nat on

55 */

56 oublic void addCestmatior (Destination destination) {

57 .tεOestmatio^s aααEIe-^ent (aesti^vation )

58 ⁱ 59

60 /^»*

61 * Clears all dest_^nat.o-'S from the Agentε Itinerar

62 -/

63 oublic void c.earl _~erary ( ) {

64 i tεDeε ti^-t.cs removeAHΞleme" tε ( )

65 }

66

67 r

68 * Reεetε the Iti-erary back to tne mit.al Destination

69 * This method cc ld ce uεed to force an Age~t to restart

70 * ltε Itinerary c re^_s_t ail Destinations

71 '

72 public void () {

73 tεCurrentS-oo = -"

74 } 75 76 77

78 * Retrieves tne ceεt_-a^~_o-' oojett .de^t^t i^ t-= current

79 * location r the - e--

30 * Θreturns T e Agent ε current locat_c-

31 * Sexcect." NcSuc-rlementExcection If the Age-- aε not 82 * travelled S3 */

84 public Destin tion ge^C-rrentLocat.on ( ) throws NoS_^chΞlementExceotion {

85 try {

86 return (Deεtmati-- ) itεDeεtinationε element t ( itsCurrentStop)

87 } catch (ArraylndexOutOfBoundsException boundError) { thrc new NoSuchElementE^vcep ion ( )

89 }

90 }

91

92 /**

93 * Retrieves the αest.nation object identifying the current

94 * location of the r-σe-t

Itinerary. java_l Tue Nov 12 07:45:03 1996 3

95 * Θreturns The Agent's next destination

96 * @exception NoSuchElementException If the Agent has not

97 * travelled

98 */

99 publ ic Dest i nation getNextDes t mat ion ( ) throws NoSuchElementException {

100 try {

101 return (Des tira ion) ltsDeε tinations elementAt ( l tsCurrentStop+1 ) ,

102 } catch (ArraylndexOutOfBoundsException boundError) {

103 throw new NoSuchElementException ( )

104 )

105 } 106

107 /**

108 * Retπeveε a" enum ration of all of the Destinations ir the

109 * Itinerary

110 * Θreturns An enumeration of all of the Destinations in the

111 * Itinerary

112 */

113 public Enumeration destinations!) {

114 return i tsDestmationε elements (),

115 }

116

117 /**

118 * Makes a clone of the Itinerary If the reset parameter is true

119 * then the new Itinerary is reset to the first destination If

120 * reset is false, t en the new itinerary is set such that its next

121 * destination is tne same aε that of the original

122 * dpararn reset true if the new itinerary srould be reεet to

123 * the first destination

124 * (?returns -v cion= of the oπgi-al Itinerary

125 */

126 puolic Itinerary clo^el tmerary (boolean reset) {

127 Itiⁿerary clone = new Itinerary)) , 128

129 Enumeration enum = itsDeε tinations elements!),

130 while (enum nasMoreEle ents ( ) ) {

131 Destination original = (Destination) enum nextElement ( ) ;

132 Destination cloneDest = (Destination) original cloneDestination ( ) ,

133 clone addDest mat ion (cloneDeεt )

134 }

135

136 if ('reset)

137 clone I tsCurrentStop = l tsCurrent top

138

139 return clone

140 } 141

Itinerary. java_l Tue Nov 12 07:45:03 1996 4

142 /**

143 * Retrieves the next destination to which an Agent should

144 * travel ard increments the Itineraries internal state to

145 * the next destination Thiε method is called internally

146 * by the ConduitServer when it is preparing to transport

147 * the Agent to its next destination

148 */

149 protected Destination nextDes tmation ( ) throws NoSuchElementException {

150 try {

151 return (Destinat on) ltsDestmations elementAt ( ++ ltεCurrentStop) , 152

153 } catch (Ar ylndexOutOfBoundsException boundError) {

154 throw new NoSucnElementException ( ) ;

155 }

156 }

157 }

MemoryWatch. ava_l Tuβ Nov 12 07:45:03 1996 1

1 /* $Header /com/mei ca/hsl /zones _jagentε/conduit/MemoryWatch ava 3 11/11/96 5 15p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubiεhi Electric Information Technology Center America

5 * All πghtε reεerved

6

7 * CONFIDENTIAL ANϋ PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8

9 * DESCRIPTION

10 * Conduit Server implementation

11 *

12 * $Log /com/meιtca/hs_/zoneεjagentΞ/conduιt/MemoryWatch java $ 13

14 * 3 11/11/96 5 15p Billp

15 * Made correction to company name

16 *

17 * 2 10/28/96 6 31p Walsn

18 * Add more debugcirg info

19 *

23 */

24 package com meitca h_sχ zoneεjagerts conduit, 25

26 import ava util * 27

28 import com meitca hsl util ^"* 29

30 /**

31 * The memory <ιatch class provides an minimum priority thread which

32 * reports the total amourt of memory allocated to the Java VM as

33 * well as the amount of tree memory currently available

34 *

35 * To enable the MemoryWatch the Conduit Server should be started

36 * up with the following switch passed into java exe

37 * -DDebug=" conduit memory watch=4 '

38 * Θauthor Thcrras alsn

3 "9 * '/

40 c lass MemoryWatch e den - Thread {

41

42 /** The nunoer of f-illiseconds between pollε of the VM */

43 εtatic int collmglnterval = 5000, // in millisec 44

45 /** Constructs a MemoryWatch object */

46 Memory atch ( ) {

47 Debug pr tln ( 'condui t memory watch 1 Memory Watch t read εtartmg )

MemoryWa ch . j ava_l Tue Nov 12 07:45:03 1996 2

48 setPriority (Thread.MIN_PRIORITY) ; 49 start () 50 } 51 52 /** Performs memory polling */ 53 public void run() { 54 while (true) { 55 Debug .println ( "conduit .memory .watch" , 4, " " ) ; 56 Debug .printlnf "conduit .memory. watch" , 4, "Server up since: " + ConduitServerlmpl . getStartu me ( ) ) ; 57 58 long uptime = ConduitServerlmpl .getUpTime () ; 59 Date up_date = new Date (uptime) ; 60 Date bigBang = new Date(0) ; 61 Debug .println ( "condui .memor .watch" , 4, "Server uptime: " + 62 (up_date .getYear ( ) - bigBang . getYear () ) + " years, " + 63 (up_date .getMonth ( ) - bigBang .getMonth () ) + " months, " + 64 (up_date .getDate ( ) - bigBang .getDate () ) + " days, " + 65 (up_date . getHours ( ) - bigBang . getHours () ) + " hours, " + 66 (up_date .getMinutes ( ) - bigBang .getMinutes () ) + " minutes,

67 (up_date . getSeconds ( ) - bigBang . getSeconds () ) + " seconds.

68

69 Debug . println ( "condui .memory .watch" , 4, "Total number of Agents : \ t\t\ " + ConduitServerlm getTotalAgentCount ( ) ) ;

70 Debug .println ( "condui t . memory .wa ch" , 4, "Current number of Agents :\t\t" + ConduitServerlm getCurrentAgentCount ( ) ) ;

71 Debug . println ( "condui t memory watch", 4, "Peak number of Agents : \ \ \ " + ConduitServerlmp etPeakAgentCount ( ) ) ;

72 Debug .println ( "condui .memory .watch" , 4, "Total memory allocated to system:\t" + Runtime. g untime ( ) . totalMemory ( ) ) ;

73 Debug .println ( "conduit .memory .watch" , 4, "Total free memory available : \t\t " + Runtime .getR ime ( ) . freeMemory( ) ) ;

74 Debug .println ( "condui .memory .watch" , 4, " " ) ;

75 try {

76 sleep (pollinglnterval ) ;

77 } catch (InterruptedException e) {

78 Debug .println ( "condui t .memor .watch" , 4, "Some thread interrupted the MemoryWatch ing sleep. Continuing");

79 }

80 }

81 } 82

83 }

MobileCodebase. java_l Tue Nov 12 07:45:03 1996 1

1 /* $Header.: /com/mei ca/hsl/zonesjagents/condui /MobileCodebase . Java 5 11/11/96 5:15p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubiεhi Electric Information Technology Center America.

5 * All rights reserved.

6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

9 * DESCRIPTION

10 * Agent Mobile codebase object

11 *

12 * $Log: /com/meitca/hsl/zonesjagents/conduit/MobileCodebase . Java $

13 *

14 * 5 11/11/96 5:15p Billp .

15 * Made correction to company name.

16 *

17 * 4 9/30/96 7:06p Walsh

18 * clean up javadoc comments

19 *

20 * 3 8/13/96 11:18a Walsh

21 * Add documentation & comments. Set up use of HashTable for bytecode

22 * storage.

23 *

24 * 2 8/09/96 4:38p Walsh

25 * Setting up file headerε

26 */

27 package com. meitca . hεl . zones jagents . condui t ; 28

29 import java . util . Hashtable ;

30

31

32 /**

33 * Contains the bytecodes for the objects that travel with an Agent.

34 * dsee Agent

35 * Sauthor Thomaε Walsh

36 */

37 public class MobileCodebase {

38 /**

39 * Provides for easy εtorage and retrieval of bytecodes. Bytecodes

40 * are stored in a Hashtable and are accessible by fully qualified

41 * Clasε name (ie " ava . lang . String" ) .

42 */

43 Hashtable i tsByteCodes ;

44

45 /**

46 * Constructs a MobileCodebase object

47 */

MobileCodebase . j ava_l Tue Nov 12 07 : 45 : 03 1996 2

48 public MobileCodebase!) {

49 itsByteCodes = new Hashtable ();

50 }

51

52 r

53 * Stores an objects bytecodes into the MobileCodebase

54 * βparam name The fully qualified Class name (le

55 * <b>"java lang Stπng"</b>)

56 * Θparam code The Class's bytecodeε

57 */

58 public void storeCode (String name, byte[] code) {

59 itεByteCodes put (name, code),

60 } 61

62 /**

63 * Retrieves an objects bytecodes from the MobileCodeoaεe

64 * Θparam name The fully qualified Claεs name (le

65 * <b>"java lang Stπng"</b>)

66 */

67 public byte [ ] getCode (String name) {

68 return (byte[J) itsByteCodeε get (name),

69 )

70 )

RemoteClassLoader. ava_l Tue Nov 12 07:45:14 1996 1

1 /* $Header: /com/mei tca/hsl /zonesjagents/remoteloader/RemoteClassLoader . Java 4 11/11/96 5:15p Bⁱll

2

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America.

5 * All rights reserved. 6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8 *

9 * DESCRIPTION

10 * Remote claεε loader distributed interface

11

12 * $Log : /com/mei tca/hs l / zones jagentε / remote loade /RemoteClassLoader . j ava $

13

14 * 4 11/11/96 5:15p Billp

15 * Made correction to company name

16 *

17 * 3 9/28/96 6:39p Walsh

18 * Add new parameter to ret r ieveClass method 19

20 * 2 8/27/96 4:10p Walsh

21 * retrieveClaεs throws ClassNotFoundException (compiler games)

22

23 * 1 8/19/96 5:28p Walsh

24 * Initial version

25 */

26 package com. meitca .hsl . zones agents . remoteloader ; 27

28 import java . rmi . Remote ;

29 import Java . rmi . Remo eExcep ion ; 30

31

32 /**

33 * RemoteClassLoader is an RMI diεtributed interface. It provideε a

34 * mechanism by which conduit servers can retrieve bytecodes for classes

35 * that exist on machines other than the one on which the conduit

36 * server iε loading.

37 * Θsee Condui Server

38 * Θauthor Thomas Walsh

39 */

40 public interface RemoteClasεLoader extends Remote {

41

42 /**

43 * Retrieve the bytecodes for the εpecified class.

44 * Θparam classURL An URL εpecifying the claεε to be loaded.

45 * This εhould be of the form /directory_path/classπame

46 * Θreturn The bytecodeε for the claεs.

47 * Sexception RemoteException If an error occurs communicating.

RemoteClassLoader. java_l TUΘ Nov 12 07:45:14 1996 2

48 */ 4 499 public byte[) retrieveClaεε (String codebaεeURL, String className) throws RemoteException,

5 500 ClassNotFoundException; 51 )

RemoteClassLoaderlmpl. java_l Tue Nov 12 07:45:14 1996 1

1 /* SHeader /com/mei tca/hs 1 / zones _jagen ts/remoteloade /RemoteClassLoade Impl java 8 11/11/96 5 15p Billp $

2 *

3 * Copyright 1996 Horizor Systems Laboratory

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL ΛIID PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA 8

9 * DESCRIPTION

10 * Remote class loader implementation

11 *

12 * $Log /com/meitca/hsl/zonesjagents/remoteloader/RemoteClassLoaderlmpl java $ 13

14 * 8 11/11/96 5 15p Billp

15 * Made correction to company name

16 *

17 * 7 10/29/96 5 31p Walsh

18 * Use ErrorLog class to report errors 19

20 * 6 10/21/96 1 26p Walsh

21 * Add some debug output

22 *

23 * 5 9/28/96 6 40p Walsn

24 * Use AgentCodebase class to load byte codes

25 * Add retr leveRemoteClass to encapsulate RMI code 26

27 * 4 9/04/96 12 33p Walsh

28 * Centralize manipulation or RMI URL Use the test security manager 29

30 * 3 8/27/96 4 18p Walsh

31 * Add silly constructor (because Sun compiler wants it) 32

33 * 2 8/23/96 3 59p Walεh

34 * Add logging message

35 *

36 * 1 8/19/96 5 28p Walsh

37 * Initial versior

38 */

39 package com meitca hsl zonesjagents remoteloader

40

41 import java rmi Remote,

42 import java rmi RemoteException

43 import java rmi server Unir a tRemoteServet

44 import java rmi server StubSecurityManager,

45 import ₃ava rmi Naming

46 import java io *,

47 import java lang Clas NotloundExcept ion

RemoteClassLoaderlmpl. java_l Tue Nov 12 07:45:14 1996

48 49

50 import com meitca hεl zoneεjagentε εecurity *,

51 import com meitca h=l zoneε agents shared *,

52 import com meitca hεl util *,

53

54 **

55 * An RMI distributed object which provides for remote retrieval of clasε

56 * bytecodeε Remoter l aεεLoederlmpl implementε the Remot°ClassLoader interface

57 * Θsee RemoteClassLoader

58 * Θauthor Thomas Walsh

59 */

60 public class RemoteClassLoade lmpl

61 extends Unicast emo'-eServer

62 implements RemoteClasεLoader ( 63

64 /**The name co whic ti a conduit εerver is bound in the RMI Regiεtry */

65 static String RMI_NAME = 'RemoteClassLoader",

66

67 /**

68 * object which actually handleε the dirty iork or retrieving class

69 * files for =a given class

70 */

71 ClassFileLoader ItsClassFileLoader 72

73

74 public RemoteClassLoader Impl ( ) throws Pemo teExcept ion {

75 itsClassFileLoader = new ClassFi leLoader ( )

76 ) 77

78 /**

79 * Retrieve the bytecodes for the specified claεs This method is invoked

80 * by RMI The calling program on the other side of the RMI connection

81 * usually invokes the RMI by calling the

82 * RemoteClassLoader ret leveRemoteClass method below

83 * Sparam claεεJRL An URL specifying the class to be loaded

84 * This εhould be of the form /dιrectory_path/classname

85 * Θreturn The bytecodes for the clasε

90 Debug println (" remoteloader ' , 2, "loading " +

91 c 'stJame t- ' from ' + codebnse_dιr ) 9?

93 if ( (r odeb?se_dιr =- null) | | (codeb εf _ ir length!) == 0)) {

94 Doturj print In ( r not e 1 _t> κ]< t ' 1 ' 1 > id i πcj f t om r\ Λ ,'TΛ ] II ' ) ,

RemoteClassLoaderlmpl . j ava_l Tue Nov 12 07 : 45 : 14 1996 3

95 ' return i tsClaεsFi leLoader . loadClasεFi leFromClaεεPath ( c lassName ) ,

96 ) elεe {

97 Debug println (" remoteloader " , 3, "loading from directory");

98 return _l εClaεεFileLoader loadClasεFileFromDirectory (codebase_dιr , className),

99 } 100 }

101

102 /**

103 * Retrieve the bytecodeε for the specified clasε from the remote

104 * codebaεe specified by codebase_URL This method lε called internally

105 * by the Java agent system whenever an object wants to retrieve code

106 * from a RemoteClassLoader Thiε method hideε the details of the RMI

107 * Θparam codebase_URL An URL specifying the class to be loaded.

108 * This should be of the form /directory_path/claεεname

109 * Θparam className The fully qualified class name of the class whose

110 * bytecode should be retrieved

111 * Θreturn The bytecodes for the class

112 * Θexception RemoteException If an error occurs communicating

113 */

114 public static byte[] retrieveRemoteClaεε (String codebaεe_URL, String clasεName)

115 throws ClassNotFoundException {

116

117 Debug pr in In '" remoteloader " , 2, ' ret r loveRemoteClass ^• loading " +

118 class lame + ' from " + codebase_URL) ,

119

120 irt count = 0,

121 int index = 0,

122 whi le (count < 4) (

123 index = codebaεe_URL indexOff ', index),

124 if ( index == -1)

125 break, 126

127 count++ ,

128 indeχ++;

129 ) 130

131 String rmiURL,

132 String code_dιr;

133

134 if (index '= -1) (

135 rmiURL = codebase_URL εubεtrιnq(0, (index - 1));

136 code_dιr = rndehase_URI, =-ubsr t i ncj ( l ndex , eodoba '. URL length!)),

137 ) elεe { 138 rmiURL = codebaεe_URL,

139 code_dir - null,

140 ) 141

RemoteClassLoaderlmpl. java_l Tue Nov 12 07:45:14 1996 4

14 Debug pri t In i, "remoteloader " , 3, "remote object URL " + rmiURL) ,

143 Debug println ( ' emoteloader " , 3, "remote code dir " + code_dιr) ,

144

145 tr {

146 RemoteClassLoader remote = (RemoteClasεLoader) aming lookup (rmiURL⁾

147

148 return remote retr leveClaεε (oode_dιr , className)

149

150 ) catch (Exceotion e) {

151 throw new ClaεεNotFoundExcept ion ( Cound not load ' + className + e getMessage ^{( ) )}

152 }

153 } 154

155

156 /**

157 * This method is used internally to build a full RMI URL for a remote

158 * class loader on the given host

159 */

160 public static String buildRmiURL ( tring hostname) {

161 return new String ("rmi //" + hostname J- /' + RMI_NAME)

162 }

163

164 /**

165 * This method is used internally to build a full RMI URL for a remote host

168 public static String buildCodebaseURL (String hostname, String codeDir) {

169 return new r ing (bu l ldRmiURL (hoε tπame ) f / + codeDir) ,

170 } 171

172 /**

173 * A simple bootstrap which bπngε the remote clasε loader into existence,

174 * registers it name with the RMI naming service and begins listening

175 * for recuests The mam routine allows RemoteClassLoaderlmpl to

176 * be intiated from the command line via the java command

177 */

178 public static void maιn(Stnng args [ ] ) {

179 // Create and install the security manager

180 System εetSecuri yManager (new InsecurityManager!) ) ,

181 182 try {

183 // construct the εerver and regi^st r it with the RMI Naming service

184 Debug println ( "remoteloader " , 1, Create an RemoteClassLoader )

185 RemoteClassLoaderlmpl loader = new RemoteClassLoaderlmpl!), 186

187 Debug println ( " remoteloader ' , 1, "Bind it to name ' + R I_NAME) ,

188 Naming rebmd lRMI_MAME, loader),

RemoteClassLoaderlmpl. java_l Tue Nov 12 07:45:14 1996 5

189

190 Debug print In (" remoteloader " , 1 , "RemoteClassLoader Impl ready "),

191 ) catch (Exception e) {

192 ErrorLog print In (" remoteloader main", ErrorLog ΞEVERITY_FATAL,

193 "an exception occurred during startup-", e),

194 }

195 } 196

197 )

Generator. java_l Tue Nov 12 07:45:33 1996 1

1 /* $Header: /ccm/meitca/hs 1/zones_jagents/skeleton/Generator . java 5 11/11/96 5-16p Billp $

2 *

3 * Copyright 1996 Horizon Systems Laboratory,

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8 *

9 * DESCRIPTION

10 * Agent Skeleton Generator 11

12 * $Log /com/mei ca/hsl/ zonesjagents/εkeleton/Generator java $

13 *

14 * 5 11/11/96 5 16p Billp

15 * Made correction to ccmpany name 16

17 * 4 9/30/96 7 20p Walεh

18 * add javadoc comments

19 *

20 * 3 9/29/96 4 32p Walsh

21 * Allow agents to be in packages 22

23 * 2 9/12/96 ll-OOa Walsh

24 * Automatically commie the εkeleton file 25

26 * 1 9/06/96 4 54p Walεh 27

28 */

29 package com meitca hεl zoneε agents skeleton, 30

31 import sun toolε Java *,

32 import εun tools javac * 33 import Java io *,

34 import ava util *,

35

36

37 /**

38 * The Generator cl?εε generates an Method Invocation Skelton for an

39 * Agent A Method Invocation Skelton allowε the ConduitServer to

40 * dynamically invoke any method of an Agent The Skeleton εerves a

41 * similar purpose as does an RMI εkeleton or an RPC server side stub

42 * Before any Agent can travel, it is requires that a Skeleton be

43 * generated by it A programmer can generate a skeleton by executinq

44 * Generator with a ommand line like the iollowinq, - br ^

45 *<pre>

46 * java com meitca hεl zones jagents skeleton Generator agentClassname

47 * </pre>

Generator . java_l Tue Nov 12 07:45:33 1996

48 * The agentclassrame paramter should be the fully qualified class

49 * name of the agent

50 * @see ConduitServer

51 * @see Agert

52 * @εee AcentSkeleton

53 * @author Thomas Walsn

54 */

55 public class Generator {

56 57 * the main method allows Generator to be called Lrom the command 58 * line 59 */ 60 public static void main (String [ ] args) { 61 // Sanity check the command line arguments 62 f (args length < 1) { 63 Syεtem err println (StringResources NO_AGENT) 64 System err println (StringResources USAGE) 65 return 66 67 68 (args length > 1) { 69 Syεtem err print In (StringResources TOO_MANY) 70 System err print In ( tringResources USAGE), 71 return 72 73 74 String agentClassName = args[0] 75 String packageName, 76 String εhor tClaεsName 77 78 irt lastSep = agentClassName las tlnαe 0 ( '), 79 if (lastSep '= -1) ( 80 packageName = agentClassName subεtπng(0, lastSep) , 81 εhor ClaεεName = agentClassName substring ( lastSep + 1, agentClassName length!) ), 82 ) else { 83 packageName = null, 84 shortClassName = agentClassName, 85 86 87

92 String (J methodε = f indAgentMethods (agentClassName) , 93 PnntStream out = new Pr lntΞtream (new FιleOutputStream(skelFιleName) ) 94

Generator . j ava_l Tue Nov 12 07:45:33 1996

95 96 gererateSkel ₍agentClassName, packageName, εho ClassName, methodε, out⁾ 97 co pileSkel (εkelFileName) , 98 catch (ClaεεNotFound el) { 99 Syεte err println (StringResources N01_FOuND + agentClassName⁾ , 100 catch (IOExueption e2) { 101 System err prin In (Str ingReεources IO_ERPOR + εkelFileName) , 102 Syεtem err pπntln(e2 getMeεεage ( ) ) 103 e2 pπntStackTrace ( ) , 104 105 106 107 static void generateSkel (S r ing agentClaεεName, 108 String packageName, 109 String εhortClassName, 110 StπngU methods, 111 PrintStream stream) ( 112 113 // Ok This is going to be a fairly brute force approach 114 // First lets put a comment on the file 115 stream p int In ("/ /Skeleton for " + agentClassName) ; 116 stream pr ιr in ("/ /Generated by com meitca hεl zonesjagents skeleton Generator") 117 118 // The package statement 119 if (packageName '= null) 120 stream p int In ( "package + packageName + 121 122 stream println ( ' ) , 123 124 // Now some imports 125 stream pr l nt I (' impor java lang II l»cn lΛr c-essExcept ion , " ) , 126 stream println! 'import com meitca hsl zonesjagents shared Agent,"); 127 s^tream print In (" import com meitca hsl zonesjagents conduit AgentSkeleton,"), 128 stream print In (" import " + agentClassName + ", '), 129 stream println!""). 130 131 //now the class itself 132 stream print In ( "public final class + shortClaεsName + "_Skel implementε AgentSkeleton { 133 134 135 136 / define the static member variable containing the names of 137 // the objects methods 138 String methodsMember = "\tstatic public String methodε[] = { 139 for (int ι=0, i<methodε length, l+ ( 140 if (l ' = 0) { 141 methodsMember = methodsMember + " ,

Generator. java_l Tue Nov 12 07:45:33 1996 4

142 }

143 methodsMember = me hodsMember + "new Stnng(\"" + methodsfi] + "\"⁾"^,

144 }

145 methodsMember = methodsMember (- " },",

146 stream println (methodsMember ) ;

147 stream prmtln(""); 148

149

150 // now the invoke method

151 stream prin In (" \ tpubl _IC void ιnvoke(Agent agent, int i) throws IllegalAccessException {"⁾,

152 stream. println ( "\t\tswitch (l) {");

153 for (int i=0, Kmethods length, ι++) {

154 stream printin (" \ t\ t\ tease " + l + " ") ,

155 stream pπntln( "\t\t\t\t (( " + shortClassName + "(agent) " + methods[ι] + "⁽⁾,"⁾,

156 stream p intln ( " \ t \ t\ \ tbreak ; " ) ,

157 }

158 stream. rintln! " \ t\ t\ tdefaul t ")

159 stream println (" \ t\ t\ t\ throw new IllegalAccessException ( \ "Method \" + i + \" out of range \ "⁾,"⁾, 160

161 // close the switch

162 stream println (" \t\t} ') , 163

164 // close the invoke method

165 stream pr in t In ( " \ t } " ) ,

166 stream println!""), 167

168 // now the getMethods method

169 stream p int n {" \ tpubl ic String [] getMethods!) {')

170 stream. println (" \t\ t return methods,"),

171 // close the getMethods method

172 stream println (" \t} ") , 173

174 // close the class definition

175 stream. println ("}") ;

176 } 177

178 static String [] f indAgentMethods (String agentClassName) throws ClassNotFound {

179 ClassDeclaration classDecl = new ClassDeclaration ( Identi ier . lookup (agentClassName) ) ;

180 BatchEnvironment env = new BatchEnvironment (new ClassPath (System getProperty (" java class pal ))),

181 ClassDef lπition classDef = classDecl getClassDe mi tion (env) ,

182 Vector agentMethods = new Vector!); 183

184 FieldDe inition fieldDef = classDef . getFirstField () ;

185 while (fieldDef '= null) {

186 if (f leldDef . isMethod() && ' fieldDef . isConstructor ( ) && fieldDef . isPublic () ) {

187 Type argTypes [ ] = fieldDef getTypef) getArgumentTypes ( ) ;

Generator. java_l Tue Nov 12 07:45:33 1996 5

188 if (argTypes length == 0) {

189 if (fieldDef getType!) getReturnType ( ) == Type tVoid) {

190 agentMethods addElement ( fieldDef getNamef) toStringO⁾

191 }

192 )

193 }

1 94 f j.e ldDe f = f i e ldDe f ge tMextF ie ld ( )

195 ) 1 96

197 //turn it into an array

198 String!] arra = new String [agentMethods size!)]

199 for (int ι=0 KagentMethods size!) ι++) {

200 array[ι] = (String) agentMethods elementAt ( l) ,

201 ) 202

203 return array

204 }

205

206 εtatic void compi leSkel (St ing skelFileName) (

207 Main compiler = new Mam(Syεtem out, "javac")

208 String (] params = new String [1]

209 params [0] - skelFileName,

210 if ('compiler compil (paramε) ) {

211 System err p int I 'StringResources COMPILE_ERROR + skelFileName)

212 }

213 )

214 }

StringResources. java_l Tue Nov 12 07:45:33 1996 1

1 /_* SHeader /ccm/me _l tea_/ hs 1 / zones _jagents/skeleton/Str lngResources java 3 11/11/96 5 16p Billp $ 2

3 * Copyright 1996 Horizon Systems Laboratory

4 * Mitsubishi Electric Information Technology Center America

5 * All rights reserved 6

7 * CONFIDENTIAL AND PROPRIETARY PROPFRTY OF MITSUBISHI ELECTRIC ITA

8

9 * DESCRIPTION

10 * The String Resources for the skeleton package 11

12 * $Log /com/rrei tca/hsl / zonesjagents/skele ton/ tringResources ava $ 13

14 * 3 11/11/96 5 16p Billp

15 * Made correction to company name 16

17 * 2 9/12/96 11 00a Walsn

18 * Automatically compile the skeleton file

19 *

20 * 1 9/06/96 4 54p Walsh

21 *

22 */

23 package com meitca hsl zonesjagents skeleton 24

25 class Str ngResources { 26

27 // Generator java

28 public static String USAGE = Us qe generator agent c lasεname

29 public static String N0_AGEN1 = generator You must specify an aqent class name '

30 public static Strirg TOO_MANY - generator Too many parameters specified "

31 public static String NOT_FOUND = generator Agent class not found -- ',

32 public static String IO_ERROR = 'generator IO error while attempting to write the skeleton file --

33 public static String COMPILE_ERROR = generator Anb error while attempting to compile the skeleton file -

34 }

Mitsubishi Electric ITA

Patent Disclosure for

Dynamic Synchronous Collaboration

Framework for Mobile Agents

November 12, 1996

Horizon Systems Laboratory

Mitsubishi Electric ITA

1432 Main Street

Waltli m, MA 02154

Mitsubishi Electric ITA Confidential Patent Disclosure for Dynamic Synchronous Collaboration I- .amework for Mobile Agents

Patent Disclosure for Dynamic Synchronous Collaboration Framework for Mobile Agents

1. Introduction

This document serves as a patent disclosure on the invention enlitledDy/z .nic Synchronous Collaboration Framework for Mobile Agents. This document includes a discussion of: prior art. problems with prior art. details of the invention, and improvements of this invention over prior art.

2. Prior Art

"Agent^" is one of the most overused terms in the soltvvare industry today. Although the term may be used in a wide variety ol contexts, software Agents can be classified into two major categories: Intelligent Agents and Mobile Agents. Although the two differ in scope and capabilities, both types of Agents are able to perform work asynchronously and autonomously on behalf of their owners. Intelligent Agents are endowed with some degree of reasoning and learned behavior and may make decisions on behalf of their owners. These Agents are generally stationary and execute on a single system. Mobile Agents, on the other hand, may be transported across nodes in a network, performing computations as they migrate.

The original concept for Agents stems horn the Artificial Intelligence community. The behavior of Intelligent Agents may be determined by programming or by decisions made by the Agents on behalf of their owners. As an example, an Intelligent Agent may search a database for unusual outdoor scenery, making its own decisions as lo whether or not each scene meets the specified criteria.

Intelligent Agents generally employ both synchronous and asynchronous modes of communication. Agent communicalion may take the form of queries or collaborative computations. In the realm ol Agent computing collaboi ai ion may be del ined as "the coordination of the computations of multiple Agents to achieve a desired result" (e.g.. to solve a complex problem). Collaboration often results from discovery (i.e. the need to

Mitsubishi Electric ITA Confidential

1 - Λ ST - Patent Disclosure for uynamic Synchronous Collaboration rramework for Mobile Agents

collaboiate with a specific Agent lcgarding a certain subiect is not known a priori, but is. rather, detcimincd as a result ol the Agent's computations )

Both the inlet action between these Agents and the context in which they execute must be tormally specilicd. Standaidi/ation has not yet been achieved lor these objectives Howevci , the pievalent means loi accomplishing these results is via implementing a usei model and specilying queues and asseitions by using a knowledge lepiesenlation language, the most populai ol which is cuiiently Knowledge Queiy Manipulation Language (KQML), and by developing Ontologies. 01 vocabulai ies ol common tcims to be utilized by mteiacting Agents KQML is compnsed ot both a language, with a syntax unlike piocedural 01 ob)ect-oπented languages, and a communications protocol. An Ontology is delined as "an explicit specilication ol a conceptualization" The syntax and semantics ol an Ontology aie generally extensions oi a tirst-oidei picdicate calculus, typically the Knowledge Inteilace Format (KIF)

The combination ol KQML. KIF. and Ontology development is a complex task Some implementations utilizing these mechanisms aie being developed in the Aitificial Intelligence community But this approach has not caught on in other soltvvare applications

In contiast to Intelligent Agents. Mobile Agents aie usually explicitly piogrammed to accomplish a speed ic task. As an example, a Mobile Agent could migrate to travel agencies on the Woild Wide Web and determine the lowest cost air tare between two cities In this case, theie is no need loi learned behavioi oi complex reasoning

However, the amount ol lnlonnation accessible on distributed systems, including databases, the Internet and Intianets. is growing at a staggering pace and much ot it is available in incompatible stoiage lormats. The need to tiltei lnlormation and make decisions based on its content is lncicasing, and with it, the need for increased cυllaboi ation among Mobile Agents

The need toi collaboiauon is lllustiated by extending the above navel agency example A Mobile Agent may need to clone itself and instinct each ol its counterpaits to migrate to a dillcrcnt travel agency site to obtain the best package for a trip to one or more ski resorts meeting certain paiameleis. lrcludmg an laic, lodging, me.'l.s bi t tickets, and cai lental rui thei moie, tiie inhu mation may, itsell, be . oied m dilletcnt foimals (databases, etc.) necessitating some amount ot tiltcπng and data reformatting Once the Agents have obtained their intormation, they need to collaboiate with each othci to con elate their icsulls and determine the best package available at each resou l oi difteicul tiavel dates ana the overall best deal.

Mobile Λgc'iis aie e /olving to .nckide i" .ιcu.>ed mtelli C . and collaboiauon Some lescaich organizations have begun lncoipoiating KQML and Ontologies into Mobile

Mitsubishi Electric ITA Confidential 2 - Λ Sζ> - Patent Disclosure for Dynamic Synchronous Collaboration Framework for Mobile Agents

Agent implementations, while other utilize different knowdedge representation languages to implement Agent communication. Still, others use proprietary object languages.

3. Problems with Prior Art

The KQML/Onlology mechanism and other knowledge representation languages arc ill- suited for general-purpose soltware applications. They require programmers to learn multiple languages to formally specify communications and to develop complex dictionaries of teπns - a task that is currently ill-defined. The knowledge representation languages are also extremely unlike the procedural and object-oriented languages utilized in building business and general-purpose software applications.

The need to support asynchronous collaboration adds significant complexity to Agent systems implemented via knowledge representation languages (e.g. KQML) and Ontologies. Furthermore, there exists a class of Mobile Agents which solely require synchronous collaboration, e.g.. the travel agency application described above. This type of Agent application essentially subdivides a larger task into smaller pieces and creates Agents to migrate throughout the network lo accomplish it. For these Agents, there is no benefit in die added complexity of coding in multiple languages and developing Ontologies, nor in the support for asynchronous communication. A synchronous collaboration framework in the Agent^'s language is the best means for these Agents to coordinate their results and implement adaptive behavior.

4. Some Details of the Invention

The dynamic synchronous collaboration I amework utilizes a distributed synchronization point plus object-oriented abstractions to provide synchronous collaboration for Mobile Agents in a distributed system. The lramewoik simplifies collaboration for applications which subdivide a complex problem into several pieces and farm out the work to multiple Mobile Agents.

This framework enables Mobile Agents within an application lo perform synchronous collaboration with one or more affiliated Agents in the application's native language. This is accomplished via [hcAgenr Group abstraction. Agents wishing to collaboiate with each other must belong to one (or more) ol the same Agent Groups. The fundamental principle behind Agent Group collaboration is that Mobile Agents perfonning sub-computations, possibly on different nodes in a distributed system, will need to periodically correlate their results, and potentially adapt their behavior based on the rcsulLs of the correlation. The Agent Gioup acts as a distributed synchronization point ioi i is type of syncluonous collaboration.

Mitsubishi Electric ITA Confidential

3 _ S ^ _ Patent Disclosure for uynamic Synchronous Collaboration f-ramfev ork fornΛobue Agents

The dynamic natuie of the Agent Group enables Agents lo join and leave the group at will. Hence no a pπoi i knowledge ol the actual Agents comprising a group is lequπed and gioup membeiship may change over time

A distnbuted name space maintains a teterencc to each Agent Gioup Hence, Agent Gioups may be located via then entiy the name space When an Agent Gioup is cieated. U is automatically added to the name space.

The Agent Gioup s pnmaiy lesponsibilily is to lacilitale synchi onous collaboration foi Mobile Agents I lowevei, it also selves as a cential point loi disliibuting asynchi onous events to Agents in the gioup A typical event may be the teimination ol a paiticulai Agent. As a side etlect, the Agent Group also tracks the n avels ol its constituent Agents throughout the netwoik

The tiavel agency example lllustiates the lunclion ol Agent Gioups The pioblem to be solved can be stated as f ollows A usei wishes to deiei mine the best package lor a trip to a ski iesoil T he Agents must deiei mine the best navel date and time (e.g any week in Februaiy stai tmg on a Satuiday, and f lying bef ore noon) and lodging must meet certain ciitcna (e.g , a two-bedioom condominium) The tup includes all expenses (e g.. an faic. lodging, meals, li anspoi tation. and lift tickets) The usei may also speedy several possible tiavel destinations

This application is composed of multiple Agents -- each is lesponsiblc loi querying one oi more data souices (in peihaps dilferent loimats) loi specil ic inloi mation (e g , scaiching a pai ticulai tiavel agency^'s database ol promotional tups to deiei mine it any meet the catena specilied by the usei ) Some Agents may queiy legacy database systems, whereas otheis may sea: ch ODBC compliant databases (The actual mechanisms loi handling dilleient data souices is beyond the scope ol this invention )

Belore the Agenls aie tianspoitcd thioughoul the netwoik they join a new Agenl Gioup The Agent Gioup Hacks Us Agents^' navels thioughoul the netwoik. At any point, an Agent may be in one of several stales Figure 1 depicts thiec Agents in an Agent Group perloi ing computations and one Agenl in-transit between nodes

At dil leient points din ing then migiauoii. Agents may wish in ( υnelate then lesults. and potentially change then migiation plans oi behavioi Suppose each Agent migrates lo a local travel agency Bcloie migrating to tiavel agencies in dilfcicnt cities, the Agenls mav wish lo coiK'lale then lesulls and potentially adjust then behavioi Suppose one of the Agenls dctei imnes that a paiticulai ^ιkι iesoi l. say Taos, has no iwo-bedioom condominiums available dunng Febuiai y The Λgents in the gioup may wish lo di np al' luilher queues about tups lo Taos

Agent Gioup collaboration is implemented via a distnbuted synchronization point (also known as a collaboiauon point) and a soltwarc loutine to analyze the results 01 each

Mitsubishi Electric ITA Confidential 4 - ΛSX -

Patent Disclosure for Dynamic Synchronous Collaboration Framework for Mobile Agents

Agent's computation The Agent Gioup abstiaction provides the distnbuted synchronization point Fach application need only provide its own sollwaie method to analyze the results and potentially allow each Agent to adapt its behavioi

The disliibuled synchiomzalion scheme lequnes thai each Agenl auive at the collaboiauon point bcloie collaboiauon may commence Hence, it is best suited to applications that subdivide a complex pioblem into many sub-tasks that need to con elate their lesulls As each Agenl ai rives at the collaboiauon point, it posts the icsults ol its computations to the Agent Gioup. and blocks until all the olher Agents in the gioup aπive Figuie 2 depicts one Agent in the group waiting lo collaborate while three others aie still perloπning computations

The Agenl Group collects the icsults ol each Agent's sub-computation When all Agents have arrived at the collaboiauon point, as shown in Figuie 3, the Agenl Gioup nolihes them lhat collaboiauon may commence When it unblocks the waiting Agents, the Agent Gioup passes the collected lesulls lo each Agent Each Agent then calls the apphcation- specilic method lo analyze the icsults and potentially adapt its behavioi Figure 4 shows that all Agents have ainved al the collaboiauon point and aie now in the analysis stage

The synchionous collaboiauon hamewoi k suppoits both paiallel and serialized collaboiauon analysis Figuie 4 depicts a parallel analysis implementation. Figure 5 illustrates a sci ialized collaboration analysis, which one Agent is in the Analysis state. while the iesl lemain wailing in the Collaboiate slate

The distnbuted collaboiauon point may be implemented via an ob|ect tianspoi t oi by an RPC mechanism It may also be implemented in any piocedural oi ob|ccι-oncnted language Olηeci-oπented languages simplif y the implementation, as the application need only subclass the Agenl Group abstraction and piovide a concrete method to analyze the lesulls and potentially adapt the Agent's lutuie behavior

The Agenl Gioup cnsuies that all Agents in Ihe gioup aiπve at the synchronization point by H acking the Agent s migiation thiough Ihe netwoik In the current implementation, as part of a mobile Agent system, a scivcr (known as the Conduit Server) on each node manages the Agent^'s migiation and infoims each ol Us Agent Gioups when the Agent ai rives and departs Should an Agent lail to ainve al a coϋaboiation point in a pie- deleimiued. conliguiable length ol lime. Ihe Agent Gioup will "ping" Ihe Agent by sending a message to ensuie lhat it is still alive, as shown in Figuie 6. (In the cunenl implementation, this is peilormed via the Conduit Servei on the node whcie the Agent is executing II the Agent f ails lo respond to the ping, the Agent Gioup notifies (lie other membeis ot the gioup by distributing a Collaboiauon Failed asynchronous cvcnl to them lhat indicates thai a pai ticulai Agenl is not lesμondmg l^'lie Agents may then indicate whelhci or not they wish to proceed with the collaboration Figure 7 depicts the Agent Gioup^'s distiibution of a Collaboiauon Failed event followed by the remaining Agents

Mitsubishi Electric ITA Confidential

5 Patent Disclosure for Dynamic Synchronous Collaboration Framework for Mobile Agents

indicating that they wish lo continue the collaboiauon Alternatively the Agents could decide to abort the collaboiauon

T he Agent Group also implements deadlock detection b means ol the time-out mechanism and Agent ping descπbed above T he ping aciuallv letuπvs the state ot the Agent in question (via the Conduit Sei vei ) II the Agent is aheadv in the Collaborate stale but has not aiπved at this collaboi auon point a deadlock has occuned 1 his is shown in Figuie 8 In this case the Agenl Gioup will aboit the collaboration and notily the Agenls in the gioup ol the deadlock b sending them a Deadlock F v ent as shown in I lguie 9 Note that since Agenl Gioup collaboi auon is designed loi closely coordinated Agents the existence oi a deadlock is generally a lesult ol a programming erroi Hence, the Agent Group does not need to employ a ote sophisticated scheme tor deadlock detection or avoidance

Agent Gioups piovide reliability by saving the state ol each Agent in the gioup to peisistent storage If the Agent Gioup should terminate unexpectedlv. it is icstaited and leads the slate ol the group members liom peisistent stoiage The Agenl Group s icslart is tiansparcnl to the Agenls They actually communicate with an Agent Gioup Proxy (instead ol an Agent Gioup) which shields them liom Agent Gioup failures

Figure 1 1 illusuates the How ol a typical collaborating Mobile Agenl Each Agent cieaies an Agent Gioup Pi oxy loi each Agenl gi oup ii wishes lo join I he pioxv s pnmaiy responsibility is to maintain an aclive connection to us associated Agenl Gioup and to re establish the connection oi ic cieale the Agent Gioup as needed dui g Agenl Gioup lailuies

When the Agent Gioup Proxy is initialized it establishes a connection with the appiopπate Agent Gioup It lust attempts to l ind a icleience to u in ihe name space II this tails, it cieaies the Agent Group and enteis a icleience to it into the name space The algonlhm guarantees the atomicity ol this operation

Altei the proxy has cieated the Agent Gioup oi established a connection lo it the Agent continues its compulations and migrations 1 ventuallv it may allempt lo collaboiate its results T his is accomplished by means of the APCIU Gi oun Proxv II the Agent Gioup has failed oi is in a unknown state, the pioxy wil' be unable to contact ii If this occuis Ihe Agent Gioup Pioxy letπcs the communication If al this point ihe proxy is still unable to communicate with the Agent Gioup, it lecieates it and updates the name space with a rclcicnce to the new Agent Gioup Hie ic cication ol the Agent Gioup is serialized lo pievcnt multiple Agenl Gioup Pioxies liom simultaneously doing so II a pioxy detei mines lhat the vgent Gioup is in the pioces¹- ol being ic ueaied u simplv waits until U can tind a reference to the new group in uic name s t., '.⁾:ICL the Agenl Gioup has been ie-created the pioxy retries the collaboiauon

Mitsubishi Electric ITA Confidential G _ λ _>o- Patent Disclosure for Dynamic Synchronous Collaboration Framework for Mobile Agents

As mentioned earlier. Agent Groups provide a distributed events mechanism in addition to the synchronous collaboration framework. The distributed events mechanism enables the Agenl Group to notify members of Ihe group of outstanding events, such as the termination of an Agent, or ihe detection of a collaboration deadlock. Agents may build on this mechanism lo lorwai d application-generated events to other members in the group Hence, if an Agent catches an application-generated exception it may notify the other Agenls in the group before terminating. Figure 10 illustrates how the Agent Group forwards an Exception Event, generated by one of its Agents, to the rest to the group.

Currently, the Agent Group handles distributed events by maintaining a (possibly remote) reference to an event queue associated with each Agenl. The Agent Group forwards all events it receives to the other members of the group by enqueuing it. The Agent Group may be implemented without a remote referencing capability, but this would add significant complexity. In the cuireni implementation, each Agent contains an events thread which is responsible for dequeuing ihe event and calling the application-specific event handler. (This thread could easily be a process, if threads were not available.)

In addition to forwarding events to members of the group, the Agent Group may generate its own events and distribute those lo the group members. As an example, the Agent Group distributes a Deadlock Event to the group members when its detects a deadlock situation, as illustrated in Figure 9.

As mentioned earlier. Agent Groups track the migrations of their constituent Agents, with help from the Conduit Server (in ihe current implementation). If an Agenl is in transit when the Agent Group is forwarding events, il queues Ihe events locally, as shown in Figure 10. Once the Agent arrives at its destination, il notifies the Agent Group, via the Conduit Server. The Agent Group then flushes the events it stored locally for that Agent.

_*

Agenl Groups implement varying levels of persistence, as defined by the actual configuration. Memberships and Agent stales arc updated infrequently, so^'they are generally written to persistent storage. However, local queues maintained on behalf of in- transit Agents may also be saved in persistent storage, if desired.

Implementation of Ihe Agent Group in an object oiienied language enables applications io extend its functionality, if required, by subclassing the Agent Group object.

5. Benefits of the Invention

The work described above provides several benefits. It greatly simplifies the implementation oi synchi onous collaborating Mobile Agents, especially loi applications that subdivide a complex task into a series of rclaled sub-tasks. There is no need for application developers lo learn knowledge query representation languages, such as KQML, or to develop complex Ontologies. The dynamic synchronous collaboration framework provides a natural programmatic implementation that may be programmed in a

Mitsubishi Electric ITA Confidential 7 - ΛQ. K - Patent Disclosure for uynamic Synchronous Collaboration Frame αrK, for Mbbile Agents

number ol languages An added benefit of this scheme is that collaboration is implemented as part ot the application, programmed in the same language as the rest ol the application The cuiient implementation in an objeci-oπenied language (Java) also enables the technology to be easily extended so that moie complex intelligence schemes may be supported.

Agenl Gioups tacihtate Mobile Agent H cking and may also be queued by tools thai monitoi Agents In addition, collaboration may be peiloimed thiough discovery, as with many knowledge lepiesentation languages

Agent Gioups also otlei reliability by piovulmg peisistent Agenl Gioup membership and Agent state inloimation Fuitheimoie, Agenl Gioup shield Agents liom ihe ettects ot Agent Gioup tailuies They delect an Agenl Gtoup's lailuie and automatically lestail the lailed Agent Group (which then lestores ihe state ot its membership lrom persistent storage) and retry the cuirent operation (e g , collaboration) The algorithm also guarantees the atomicity ol Agent Gioup cieation and le-crealion

An Agent Group also delects Agent iailutes and deadlocks and toiwauls this information to the othei membeis ot the group via its distnbuted events mechanism Fuiihermoie, this mechanism allows Mobile Agents lo asynchionously notity associated Agenls ol ielevani events, such as the catching ol an exception

ImplementUion ol Agent Gioups in an ob]ect-oπented language also enables additional application-specific functionality to be easily added via lnheπtance and polymorphism.

Mitsubishi Electric ITA Confidential 8 Patent Disclosure for ijynamic Synchronous Collaboration Framework for Mobile Agents

6. Figures

Compute Compute

Aaeiit (Node Λ) Λsieiu (Node B )

Λgent Group ( Node Λ)

In-iransil

( 'ompute

Asient (Node !))

Agent (Node C

1 igure 1 Agents in Compute and In-ir.insii Stale

Compute Comptiie

Aaent (Node A) Agent (Node B)

Λgent Group (Node A)

Compute

Collaboiate

ΛuenKNode D)

Λ^»eni ( Nod C)

^■igure 2 Agents in Compute and Collaboration Wait Slates

Mitsubishi Electric ITA Confidential 9 Patent Disclosure for uynamic Synchronous Collaboration Framfe.«ork for Mobile Agents

Agent (Node C) Agent (Node D)

Figure 3: Agents in Collaboration Wait Slate

Mitsubishi Electric ITA Confidential 10 - Λ &« - Patent Disclosure for dynamic Synchronous Collaboration Framework for Mobile Agents

Agent (Node C) Agenl (Node D)

1 lgine 4 Agents m Parallel Analysis Slate

Collaborate Analysis

Λ»eni (Node Λ) Agenl (Node B)

Agenl Gioup (Node A)

Collaborate Collaborate

Agent (Node C) Agent (Node D)

^•igure 5 One Agent tn Serialized Analysis Stale, Others in Collaboration Wail Stale

Mitsubishi Electric ITA Confidential 11 Patent Disclosure for dynamic Synchronous Collaboration Framev.urk for Mobile Agents

Agent (Node A) A«ent (Node B)

i

Λuent (Node C Λϋeiil ( Node I ))

Figure 6. Agent Group Pings Agenl Λl iei Collaboiauon Tunes Oui

Mitsubishi Electric ITA Confidential 12 Patent Disclosure for uynamic Synchronous Collaboration Framework for Mobile Agents

Agent (Node A) Agent (Node B)

Collaborate Unknown

Collaboration Collaboration Failed kveni Failed F.venl

Agent Group ( Node A )

Collaboration Collaboration Continue Failed Fveni Con_liiuie tailed F.venl

Collaborate Collaborate

Agent ( Node C ) Agent (Node I ))

1-ιguιe 7 Co iiinued ( 'ollaborati in Despue the Failure ( 1 An Ag :nι to Respond

Mitsubishi Electric ITA Confidential 13 Patent Disclosure for Dynamic Synchronous Collaboration Framev.urk for Mobile Agents

Agent ( Node A) Agenl (Node B) Agent (Node A) Agent (Node C)

Collaboiate Collaborate Collaborate Collaborate

Agent Group 1 (Node A) Agent Group 2 (Node C)

Collaborate Collaborate Collaborate

Agenl (Node C) Agent (Node D) Agent (Node D)

Figure Collaboration Deadlock (1 'ai l 1

Mitsubishi Electric ITA Confidential 14 Patent Disclosure for uynamic Synchronous Collaboration Framework for Mobile Agents

Λaent (Node A) Λϋcnt (Node B) Agent (Node A) Λucni (Node 0)

Λ'_ent (Node C) Λaent ( Node D) Agent (Node D)

Fiaure ') Collahoraiion Deadlock (Pan 2)

Mitsubishi Electric ITA Confidential 15 Patent Disclosure for uynamic Synchronous Collaboration Framework for Mobile Agentε

<\:>ent (Node A)

Agent (Node B)

Compute

In-iransu

Fxeeplion Fvent

Queued

Agent Group (Node A) Fxeepuon

F.venl

Exception ixception Event Fven I

Compute Exception

Agent (Node C) ΛuenKNode D)

FigurelO. Fxeepuon Propagation via Agent Group Distnbuted Events

Mitsubishi Electric ITA Confidential 16 Patent Disclosure for uynamic Synchronous Collaboration Framtwork for Mobile Agents

Mitsubishi Electric ITA Confidential

17 Mitsubishi Electric ITA

Design Specification for Java Agent Coordination

Version 0.2 November 12, 1996

Horizon Systems Laboratory

Mitsubishi Electric ITA

1432 Main Street

Waltham, MA 02154

Mitsubishi Electric ITA Confidential ; Mitsubishi Electric ITA Confidential

Design Specification for Java Agent Coordination

Version 0.2¹

1. Introduction

Java agents have the capability ot αxirdinating their activities I bis coordination takes two mam loi ms synchronized collaboration and asvnclironoiis notilϊcauons t hese modes ol communication complement each other and their i plementations aie related

Collaboration he collaboration paradigm is implemented as lollows

• multiple agents pcrtorm compulations at dillereiu nodes die network,

• alter perlorming all or a subset ol their operations, agents wail al a distributed synchroni/auon point until all agents have "arrived^",

• agenis coordinate bv potentially serialized execution ol a synchionized method

Coordination can take ihe loπn ol perlorming coinpuiaiions on intermediate results and/or updating agenl itineraries

Notification

I he notification scheme uses a distributed events mechanism to communicate agenl state changes that occur asynchronously It is mainly utilized lor distributed exception handling, but may also be used to nouly related agenls ol events, such as another's termination

As described alx)ve, agent coordination utilizes distributed synchronization and event handling However. Java possesses neither of these Actually, its synchronization primitives a> e limited ιυ cntical sections on a single system and a notilicalion scheme that can only handle a single ι ρc ol event Hence, a great deal ol the complexity in the task ot agenl coordination is comprised ot implementing mechanisms to overcome Java's unsuitability tor distributed processing These mechanisms aie described in ihe remainder of this document, along vvnh ihe new objects lhat implement them

' Revision Histoiy

07/26/96 Version 0 1 Initial lcvision

1 1/12/96 Version 0 2 Ma|or changes lo Notifications and hxceptions and Collaboration sections to retlecl aeiual implementation Removed Events section

■lava Agent Collaboration/Exception Handling (11/12/96) itsubishi Electric ITA Confidential

2. Synchronization

Λs mentioned above, agent coordination requires distributed synchronization mechanisms, such as locks and events Since Java does not provide any distributed locking, we are laced with the following choice

1 Utilize a centralized locking scheme

2 Develop our own distributed locking paradigms

3 Use Java's native methods to intei lace with the operating system's synchronization primitives

The latter choice is unacceptable because it compromises the portability ol our agent intrasiructure, whereas the first option may potentially introduce considerable network overhead The second alternative also requires significant development ellorl even to implement a well-known solution to the problem

In the interest ot expediency (as required by the tightness ol our schedule), the initial Java agent intrasiructure uiihzes RMI to implement a centralized locking scheme Locking is implemented via method invocations on a potentially remote object (called an AgentGioup See Section 3 lor detail ) Λgeni coordination is implemented hv (remote) invocations on a method which requires synchronized access (See Section 3 )

3. CollaboratorAgent and AgentGroup

Agents that may wish to eollalxirate their icsults subclass CollabυiatoiA i'ent, an abstract class derived Iroin Agent Collaborator Λgeni contains a minimum ol two threads - one to perlorm computation and to travel and another to handle asynchronous event notifications Applications that contain collaborating agenls subclass CollaboratorAgent and, ot course, these derived classes may implement several computation ilueads

F.ach collaborating agent belongs to one or moie agent groups, which are descπbed by Agent ( ii oup oh|ccis Agenl ( Si oup is actually a distributed RMI object AgentGioup defines the intei lace, AgeiuGivuplmpl, an abstract base class derived Iroin PerusientEvenlGiouphtφ provides Ihe implementation (See Design Speajicat.υn Jar Di stubnied Java Events for a description ot Persistent! '.venlCiroupImpl )

An AgentGroup is essenually a unit ol coordination Hence agents may coordinate: with all die othei agents m an Λgi-niGi up They may also create new ΛgentGroups on demand, and join and leave groups at will ( In practice, AgentGroup must be subclassed lo implement agent collaboiauon However, this document does not distinguish between the base class and us derived classes and refers lo them collectively as AgentGroups )

An ΛgeniGi oup is an ob|ecl lhat is essentiall y shai ed among Ihe memlx'rs o! an agent cooidiiiution gioup It is owned by the Agent dial initially ci eaies ihe gioup (an agenl group is created by instantiating AgentGroup) and accessed via a potentially remote RMI reference.

The relationship between CollaboraiorAgenl and AgentGroup is similar lo dial of Thread and ThreadGroup A ThreadGroup maintains reierences lo the Threads composing ihe group, an AgentGroup maintains a similar list ol its CollaboratorAgents Both ThreadGi oups and AgenlGroups form a hierarchy and each contains a reference to its parent group Thread's constructors are eidier passed a reterence to a I^'hreadGroup or they save a

Java Agent Collaboration/Exception Handling (11/12/96) 3 Mitsubishi Electric ITA Confidential

reference to die parent^'s ^'I bread^'s group Likewise, CollaboratorAgent's constructors may be passed one or more AgentGroups or save a relcrence to AgentGroup ol ns parent, il it exists

However, there is one noticeable dif ference between ihe two types ol groups A 1 bread mav only belong to one I hi eadGroup at a nine, whereas a Collaboraloi Agent ay simulianeotish lie a member ol several Ageuldroups. which constitute a hierarchy Hence, 1 hi cads contain a reterence to then associated l hrcαdCu oup, bin CollaboratorΛgcnts maintain a list ol references lo iheir AgentGroups

Support loi multiple AgentGroups facilitates cooidinaiion among related gi oups ol agents and also enables the creation ot an AgentGroup hierarchy through which communication may be propagated 'I he pilot application may utilize multiple agenl groups, as shown in figuie 1

This figure portrays an example ol two AgentGroups AgentGroup A consists of three agents - one on each LAN in ihe system, whereas AgentGroup B contains agents on multiple nodes on LAN 3 A distributed application running on a configuration such as this typically creates multiple Ageuldroups w hen it needs to travel sc the WAN In ibis case, 3 agents are ci eaied in AgentGioup A one lor each LAN Once ihev arrive on a node, ihese agents clone themselves, creating more agents lo be distributed across ntκles on the LAN (e g , AgentGroup B) I his approach minimizes network iratlic over die WAN and lorms a multilevel hierarchy ol Ageuldroups Agents in the intra-LΛN groups (e g , AgentGroup B) can communicate then iesuhs, which can ihen Ix; coordinated with the inter-LAN group (1 e , AgentGioup )

Java Agent Collaboration/Exception Handling (11/12/96) Mitsubishi Electric ITA Confidential

By default, RMI passes all local objects by copy. However, the above scheme requires lhat each Agent actually maintain (remote) references to its AgentGroups. Hence, the agent infrastructure overrides some of RMI^'s object serialization methods to generate tlie required references.

4. Notifications and Exceptions

Boϋi asynchronous notification and collaboration are implemented via the associated AgentGroup object. 1 he following description serves as an example of asynchronous notification handling via distributed events. (See Design Specification Jor Distributed Java Events for more details on event handling.)

1. An agent catches an exception and wishes to noiily the other members of the group.

The agent posts an A to the AgentGroup via the group^'s postEvent method The AgentHxceptionliveni indicates ie type of exception that occurred

3 The AgentGroup posts the Λgenihxcepuonhvcni to Ihe oilier agenls in ihe group

4. Lach agent^' s F.venl Handler performs application-specific handling of the πxceptionLvent.

If the agent that caught ihe exception wishes to notily another associated Λgeni Group, it repeals the above procedure with the next AgentGroup object.

Occasionally, ihe Agent Group may genei ate events that it directly lot wards lo a member of the group (e.g., lo "ping^" il after it tails to arrive at a collaboration po i ) or others that it "multicasi.s" to its members (e.g., an Ageiu^'s failure to reply to a ping).

5. Collaboration

Agent collaboration is more complicated than asynchronous notifications. It is implemented as follows:

1. An ageni performs some computation and arrives at a synchronization poini. o The agent performs a (remote) invocation of the AgeniGroup's collaborate method, passing ii an AgentSiams object.

3. If no collaboration is in-progress (i.e., this is ihe first agent thai has requested collaboration), collaborate calls Us synchronized beginCollabυraie method, which initializes the number of agents to wail for before collahoraiion may Iwgin (i.e., n- \ for an H-agent group. ) (Race conditions are handled by checking if ihe agent cotinl has been initialized (i.e.. it is non-zei o) hef^'oi e continuing. A l ace implies that Iwu agenls aie attempting to iniiiaie the same collahoraiion. Otherwise the application is semantically incorrect.) This routine saves die requesting agent^'s unique II) (obtained from the AαentStatus object) and starts a collaboration timer (with sufficient time for agents to arrive across tlie WAN) by passing a configurable lime-out value lo the AgeniGroup^'s wait method.

4. Otherwise (i.e., if a collaboration is in-progress), collaborate calls the synchronized decrenientCollaborate method to add the requesting agent^'s unique ID lo the list of

Java Agent Collaboration/Exception Handling (11/12/96) Mitsubishi Electric ITA Confidential

agents arriving at the collaboration point and to decrement the waiting agent counter. If the counter is non-zero, ilns method hhxks with no time-out value Otherwise, ihe Agent Group awakens the other threads waiting lor collaboration to commence

5 If the timer expiies, all agents did not arrive ai ihe collalxiration point in lime Tins may occur because an agenl received an uncaughi exception and terminated unexpectedly oi because a deadlock condition exists (Since agenls may belong to multiple groups, overlapping collaboiations could result m deadlock However, a properly coded application will not generate dcadhx'ks because the collalxiration points must be known a priori and must be executed in ihe same order among collaborating agents, i e , collalxiration must fu st handled at the leal Agent Group and propagated up the hierarchy ) It a time-out exxurs, Ihe Agent Group thread initialing the collalxiration (on behall of its associated CollaboratorAgent) is awakened and perlorms (he lollowing.

• It calls Ihe AgeniGroup^'s c liet k Ciillaborate method which returns the collalxiration slate (cither CollaboiatiυnSmcecded or CollaboiauυnFailed, depending on the value ot the waiting agenl count)

• If the collaboration tailed, ihe collaborate method calls recovei Collaborate ^'I bis nietluxl attempts to communicate with the agents that did not arrive at the collaboration point by "pinging ^' them (Il determines these agents by comparing (he list ot arrived agents with the group membership ) The ping is actually perlormed via a message to the Conduit Server on Ihe node where each agent was last known to be executing II the agents are kxatcd and any ol them is in the Collaboiate state and but has not arrived at tins collalxiration point, a collalxiration deadlock has occurred and the collaboration state is sel to CollaborationDeadlock It any ot the agents cannot be located, the collalxiration stale is sel to Cυllaborauonl'ailed Otherwise, it is set to CollaboiatioiiRein and the Agent Group thread retries the collaboi auon up to a configui able number ol nines (atier which Ihe siale will Ix; sel lo Collaboiatioiil-ailed it tlie collaboiauon slid limes oui )

• The initialing Agent Gioup thread wakes up (he oilier blocked threads by calling notijvAll on the Λgentt iroup

6 Once all the collaborating Agent Gioup threads have been awakened, (euher because the counter has dropped to 0 or a time-oui occurred), they call ihe AgeniGroup^'s checkCollabυiate method II this nietluxl returns a stale other the CollaborationSucceeded, each thread returns the appropriate exception (I e , either CollaborattonFailedException or ColkώoiatiυnDeadlockl. xception) to its invoking CollaboratorAeeni

7 II ihe collalxiration slate is CollaboraiionSucceeded, collaboration commences by executing a potentially synchronized applicaiiυn-specific nietluxl, unal zeResults, to perform the collaboration analyzekesiilts is an absiiact AgentGroup nietluxl lhat must be implemented by derived classes to pri loi ni application-speci fic collalxiration As a result ol collaboiauon, agαit uineiai .es may be updaicJ

8 As each thread completes its collahoraiion, it replies to the remote collaborate invocation, passing any stale specilied by Ihe implementation, (e g , updated itineraries) The agents then continue execution on their current inxle and travel as required by dieir itineraries

Java Agent Collaboration/Exception Handling (11/12/96) ~ \y-\ _^-

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As descπbed above, collaboration requires complex mechanisms However, most of these are necessitated by the limited synchronization primitives provided by Java

Java Agent Collaboration/Exception Handling (11/12/96) Mitsubishi Electric ITA

Design Specification for Distributed Java Events

Version 0.2 November 12, 1996

Horizon Systems Laboratory

Mitsubishi Electric ITA

1432 Main Street

Waltham, MA 02154

Mitsubishi Electric ITA Confidential ; Mitsubishi Electric ITA Confidential

Design Specification for Distributed Java Events

Version 0.2

1. Introduction

This document describes a general-purpose solution to distributed event management.

2. Overview

This section provides a high-level description of Ihe objects that implement the distributed events Iiaine ork

2.1. Objects

Events

Hvents are descrilied by classes that derive from EvciitTxpe l -.ach HventType objeci includes: a unique ID (a Siring) generaled by Ihe constructors and a description of ihe eveni (a String) optionally passed to die constructors.

Event Handler

The Eventtiandler interface specifies the liandleEveiuO method which implements an livent Handler, l-ach application must provide its own F.venl Handler to perform application- specific event management.

Event Notification

The EveniPυst interface specifies the postEvenK ) nietluxl which implements event notification. Several of die classes described below implement this interface.

Eveni Gueufi

Any objeci receiving notification D( events must own an I -.vent Queue and an associaied thread that manages ihe queue. The I -.vent Queue^'s constructor is passed an kventl landler stub. It instantiates an Eveni iteueTinead (a proiecicJ class derived from Tliread) to manage the queue and passes ihe fan ici siuli to its constructor. Tlie EventQueueThread^'s ninQ mediod removes events from the queue and calls the handlelZventO method.

' Revision History:

09/26/96 Version 0.1 Initial revision.

1 1/12/96 Version 0.2 Expanded discussion of F.veiH Manager and livcnl (iroup. Added Reliability

Features and Garbage Collection sections.

Distributed Java Events (11/12/96) Mitsubishi Electric ITA Confidential

An Event Queue is a distributed RMI objeci F.vcniQueuelmpl implements the EventPost interface by appending the specified HventType object to the queue and calling the associated EventQiteneTliread^' nietluxl I ins action wakes up the hveniQueuc^'I hread tit it was blocked) I he thread then proceeds to dequeue each pending event and pass it to the handlehventO method

Event Manager

The hvent Manager handles ihe registration, posting, and notification ol events When objects request notification ol specilic event lypes, they must pass the hvent Manager a reterence to their EventPost interlace. I he I -.vent Manager saves the reference in a hash table that it uses to map event types to Iheir notification requests When an object posts an event (via the hvent Manager^'s posiEveniO meiluxl), ihe l-.vent Manager obtains Ihe list ol objects lo notily Irom ihe hash table and calls each ol their posihveniO methods

The hvent Manager also maintains a hsl ol objecls lhat have i cquested notification ol all events Whenever it i cceives an eveni, the hvent Manager also loi wards it to these objects, by calling each ol their posthventO methods hveiuManager is an RMI distributed oh|eci E\ entMana^eι dcscπlx;s the interlace, whereas EveniManagerlmpl provides the implementation hveiuManager defines methods lo manage event registrations (e g , add and delete legislations) hventManagerlmpl also lmplemenis the EventPost interlace Its posthventO nietluxl is passed an event Irom its oπginaioi and notifies ie leeipienis ol ihe event by invoking their posthventO methods

Λt most one hvent Manager runs on each nixie in Ihe Agent system A relerence lo il can be obtained via the RMI Registry

Event Group

A group ol objects interested in a common set ol notifications may lorm an Event Group hveniCiroup is a distributed RMI object EveniGroiψ defines ihe interlace, enιGrouplιnpl consists ol the implementation hvenlGroup defines methods that manage the group (e , add and remove members)

Whereas the Event Manager filters posted events on behall ol Us clients, lorwarding them only die events they requested, the hvent Group perlorms no filtering hveniGroupImpl implements the EventPost interlace However, its posthventO nietluxl torwai ds each event it receives lo every member ol Ihe group (by calling their posthventO methods)

In piacttce, Event Groups should he IHCCI spai ingly becau se (key could allow .in abusive application io gcnci aic unwanted notifications ^'I he Agent h amework does utilize (his mechanism, but n lfi s that all events are genei aied bv a group niembei and it only uiilr/es the Event Gioup fo^r some well-known events, such as ihe term ination ol an Agent hach hvent Group is ldentilied by a unique name either s e u< us const, u ioi or assigned by it. Objects may obtain a handle lo a particular hvent Group by presenting the RMI regislry widi this unique name

2.2. Reliability Features

The Distributed Events framework uicoi porates several reliability features These generally lake the lorm ol persistent slate and pioxy objects

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Event Manager

The Distributed Evenls iramew k shields objects li om ihe ellects ot Event Manager tailures in two ways

• by sav ing its stale ( i e , eni icϋistralions) to pei sistent storage, and

• bv encapsulating us lunclionaliiN in a prow ob|ecl

The Event Managei saves ihe follow ing items in ihe pei sistent store

• the hash table mapping specilic types to the objects registered to receive Ihein and

• the list ot obiecis to be notif ied ol all events

I ach time an ol ecl either registers or iinregistei s ns interest in receiving anv (or all) events, Ihe Event Manger writes ihe updated event registrations (1 e , either the hash table or the list ol objects, but not both) to persistent storage \ ιa the Persistent Storage Manager l hese are lairlv lntrequeni operations, so the pei lorinance impact ol this process should be negligible (See Design Spec ific ation loi Aqent Pei sisienc e Package lor details on the Persistent Store Manager j

Whenever the 1 vein Manager is started, 1 is mitiah/aiion code attempts to recover anv existing event registi auons Irom persistent stoi gc Hence, registrations are not lost when the Event Manager lads

In addition, the 1 vein Managei Pi ow also pievulls Objects Irom experiencing the e llects ol 1 \ ent Manasei laihnes II aeis as a wiappei olηcci lor the 1 vent Manager 1 ach Object w ishing lo communicate wiih the 1 s ent Managei nnisi first create an / object I he proxy obtains a relerence lo the 1 vein Manager via the RMI Registry It, at am [loini, the proxv is unable to communicate with the 1 \ enι Manager, il will attempt to obtain a new relerence Irom the rcgistn It will reti v this operation several times belore throwing an exception

Furthermore, il the 1 vent Managei should la , it will automatically be re-stai ted b\ the Java Agent System

Persistent Event Group

I he Dismbuied 1 veins l jncwι„ ,_^ rrovuιc> a ener al purpose implementation oi 1 vent Groups (l e , 1 veniGroupl, as descnbed ,iπo\ e i lowevci a also piovidcs ,ι reliable implementation ol Eveni Groups I'ersislcnl I vein Groups l'ei st cnt I wnt Group is a distributed RMI object thai extends EveniGroup the interface is defined bv PeiststeniEventGioiip and Ihe implementation is piovided by Peii entLventGioiψl ipl, a subclass ol EveniGioisnlinpl ei sisieei 1 veni Gioup mili/es persistent storage in much ιh( same manner as die livent Manager Whenever an Object joins or leaves the gioiφ, it s ve a reference to it in persisienl storage

Each Persistent Event Group is also encapsulated m a proxy object PersislentEvenlGwupProπ Hits proxy operates somewhat dillereuily than die Event Manager Proxy, depending on how u is constructed In some cases, it will attempt to locate a named Persistent Event Group in the RMI registry If a name is not supplied to the constructor, it will cieate a new Persistent Event Group and register it

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Since Eveni Groups are temporary objecls, unlike the Event Manager, which is a persistent server, their proxies cannot expect their associated Persistent E.vent Groups to be automatically re-stai ied upon failure. Hence, a proxy may i c-creaie Ihe group if it is unable to obtain a reference lo il alter sul licieiil ictries.

This, however, introduces a race condition wherein multiple |)roxy objects may simultaneously attempt lo re-ci eale the Persistent E.vent Group. This is handled by ihe following mechanism:

• If ihe owner of the Persistent Event Group delects the failure, it re-creates the group. (The owner is defined as ihe proxy that initially created the group.)

• If the owner does not detect the failure m a configurable length of time, otfier proxies may attempt to re-create it.

• ^'I he Persistent Event Group is re-created via the following steps:

• Attempt to create a temporal y binding in the RMI name pace with a well-known name derived from the Persistent Event Group's unique name.

• If the binding dtx;s not return an AlreadxIknindE.xcepiion, proceed to re-create the PersistentEventGroiip and then remove the temporary binding. (Otherwise, another proxy is re-creating it. So wait for its completion.)

2.3. Garbage Collection

Both Ihe Eveni Manager and Eveni Group ob|ccιs musi Ix: prcjinred to garbage collect stale references. This is simply pei loi med by deleting any objects (i e., EventPost stubs) thai il cannot communicate with. Hence their posiEventO inethixls handle gai bage collection alter notifying all interested objects ol ihe eveni.

3. Changes to Agent Implementation

CollaboratorAgent

The Collaborator A qeiU class contains a reference to an event tjueue (i.e., an Evcnt'. ucuelmpl object), which is instantiated by us constructors.

The Event Queue dcxi.s not persist across an Agent's travels. Hence, its prcpareE^'orTransiH ) method Hushes the queue and voids Ihe Agent's relerence to the queue before it travels. Its associated Agenl Groups save any events that occur while the Agent is in-transit. The conψletetl^'l^'raitspoili ) method, called al^'lei Ihe Λgeni amves al us destination, consli ucts a new EveniQueueln.pl object and i lnsl-i s an evenu _a-. -.d by the associated Agent Groups while the Agent was in-transit.

AgentStatus

The AgentStatus class contains a reference to the EventPost interlace implemented by the CollaboratorAgent^'s Event Queue. It also contains an Agent's unique II) and current status. Hence, it will serve as both an Event Queue and a status indicator.

Distributed Java Events (11/12/96) Mitsubishi Electric ITA Confidential

AgentGrouplmpl

The AgentGrouplmpl class derives Irom PersisicniEventGroupImpl Thus, it not only enables Agent collaboration, but also provides reliable group event handling

As a result, Agent (jroups may implement dillei ent levels ol pei sistence Group niemhoi ship is always written lo persisient storage, bin queued events lor in-transit agents will also be saved il Ihe Agent Group^'s conliguiation allows it

Occasionally, Ihe Agent Group may generate events that it diiecily torwards to ^■> member ol the group (e g , to "ping" it alter it tails to aπ ive at a collalxiration point) or others lhat it "multicasis ^' to its members (e g , an Agent^'s lailure to l eply to a p g) Group members mas also broadcast an event to ihe group (e g , an Agent may inlorni the group that it has encountered an exceptional condition)

AgentEvent

T he A t>entEvenι class is the superclass of all events generaled by Agents It includes the Agent^'s unique ID

Distributed Java Events (11/12/96) AgentGroup. java_l Mon Nov 11 16:25:52 1996 1

1 /* $Headeι • /com/me_ tca/hs.. zones_jagent 'col labcrate /AgentGroup ₃ava 5 10/01/96 3-40p Noemⁱ $

2 *

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology C^3rιter America

5 * All rights reservec 6

7 * CONFIDENTIAL ANT, PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8

9 * DESCRIPTION

10 * Agent Group distributed interface 11

12 * $Log 'cora/reitca/ sl ' zonesjagents , collaborate/ AgentGroup . java $

13

14 * 5 10/01/96 3 40p Noemi

15 * Added some ₃avad;c comments 16

17 * 4 9/10/96 5 0^"p Nor-π

18 * Changed return value of collaborate method from a void to an Object 19

20 * 3 9/06/96 3 34p Noemi

21 * Added UpdateAger method. changed argument to addAgent

22 *

23 * 2 8/30/96 4 24p N~emι

24 * Added addAgent, reraoveAge t, and getGroupSize metnodε

25 *

26 * 1 8/28/96 2 : 13p Noer

27 * Basic AgentGroup f j.ictical i ty No F ipport for remote groups or agent

28 * mobility yet

29 */ 30

31 package com.meitce '-si zoreε;agents collaborate,

32

33 impor t j ava . ut i l K ~SuchE emfc i tExcept i on ,

34

35 import j ava . rmi . Remo te ;

36 import j ava . rmi . Rerac ieExce . i :n ;

37

38

39 /**

40 * AgentGroup is an RMI distributed interface The actual

41 * implementation o^-' AgentGro p is handled by AgentGrouplmpl

42 * This class provides RMI glue that enables Agents to invoke

43 * (remote) operations on on associate agent gioup 44

45 * Agents may belong to one c r more agent coordination groups

46 * (AgentGroups), which act as focal points for distributed

47 * synchronous agent collaboration and asynchronous notifications

AgentGroup. ava_l Mon Nov 11 16:25:52 1996 2

48 * among members of the age it gioup

49 *

50 * ©see Agent

51 * @see AgentGr n.ulmpl

52 * ©author Noemi Par orek

53 */ 54

55 public interface AτentGrcuo

56 extends Remote 57

58 // Instance methods

59 /**

60 * Collaborati n interface

61 * @param resu.t Ti; result of the agent's computation

62 * RemoteException If an error occurrs setting up network

63 * connections

64 * (sexception •ⁱcιentGrc pFv cept ion If the collaboration imes out

65 * ©return An ODject tnat describes the result cf collaboration

66 */

67 public Object collaborate ( AgentResult result)

68 throws RemoteException AgentGroupExcep ion

69

70 /**

71 * Adds an Agent to the gro p

72 * Θparam status The AgentStatus object that describes the Agent

73 * ©exception RemoteException If an error occurrs setting up network

74 * connections

75 */

76 public void adα^gent ₍Age Status status-)

77 throws RerroteExceotio 78

79 /**

80 * Locates ana removes the AgentStatus object cortairing the specified ID

81 * ©param agentID An Agent's unique ID

82 * ©exception Renott-rxc-ction It an error orcur^vs retting up network

83 * connections

84 * ©exception NoSuchElementException If the AgentStatus object does

85 * not exist

86 */

87 public void removeAgent (Sti mg agentID)

88 throws Rem^oteException, ArraylndexOutOfBoundsExcep ion, NoSuchElementExcep ion

89

90 /**

91 * Replaces the AgentStatus object for the specified ID

92 * This method may be used to change an Agent's status, ID, or both

93 * ©param c-gentID An Agent's unique ID

94 * ©param newStatus An AgentStatus object to replace the existing one

AgόntGroup. ava_l Mon Nov 11 16:25:52 1996 3

95 * ©exception RemoteExcep on If an error occurrs setting up network

96 * connectior,;-

97 * ©exception NoSuchElementException If the AgentStatus object does 98 * not exist

99 */

100 public void ^• dateAgent (S "r mg agentID, AgentStatus status)

101 throws Rferc eExceptio , ArraylndexOutOfBoundsException, oSuchElementException ; 102

103 /**

104 * Returns the number of Agents in the group

105 * ©return The number of Agents in the group

106 * ©exception RemoteExcep ion If an error occurrs setting up network

107 * connections

108 */

109 public int getGroupSxze ( .

110 throws RemoteException- 111

112 / *

113 * TURN ON LATER

114 * 115

136 public void agentExceptioi. (String agentID, Exception type) throws RemoteException, 117

113 public void agsntTerminatic.n (String agentID) throws RemoteExcep ion,

119 120 121 122 123

AgentGroupException. ava_l KOΛ 'JO 11 16:25:52 1996 1

1 /_* $Header /com_/, itca/r ε 1 / : ;nes_jagents/collabcrate/AgentGroupExceptιon java 2 10/01/96 3 41p Noemi $

2

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center America

5 * All rights reserved 6

7 * CONFIDENTIAL ^ND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8

9 * DESCRIPTION 10 * Agent Group exceptions 11

12 * $Log 'co- mei ca hεl tonesj agents /col laborate/AgentGroupException Java $ 13

14 * 2 10/01/9c 3 41p iosri

15 * Added a prote ted default constructor and some javadoc comments 16

17 * 1 8/28/96 I 16 o Nc -r

18 * AgentGroup re_ated except- --ns

19 */ 20

21 package com meι^__a hsl zonesjagents collaoorate

22

23 import com meitca hεl zonesjagents shared Age^t

24

25 /**

26 * AgentGroupEx - ,tιon defines exceptions that occur during

27 * AgentGroup operations

28 *

29 * ©see Agen'

30 * ©see AgentSrouo

31 * ©author Noem_ Pac orek

32 */ 33

34 public class AσertGrouoException extends Exception {

35 ^'

36 //Constructors

37

38 /**

39 * Constructs -n AgentGrouj Exception

40 * ©except- n Illeg lAccessException Whenever called

41 */

42 protected Agt -' OroupExcep i n ( )

43 throws I - galAcceεsException { 44

45 System out cπntln ( "Default constructor called for AgentGroupException" ) ,

46 throw new . egalAccessException ( ' AgentGroupException Default constructor"),

47 }

AgentGroupException. java_l Mon Λov 11 16: 5:52 1996

48 49 50 Constructs AσentGroupΞxception 51 ©param tv A Strirg describing the exception 52 53 public AgentGr' OD^ΓX'" =p l nn (String type) ( 54 super (type! 55 56 57

AgentGroupImpl.₃ ava_l Ilor. -JO 11 16:₂5:5₂ 1996 1

1 /* $Header /cor m« tca/hsl/z~nes_jagents /collaborate/AgentGroudmpl ava 7 10/01/96 3 43p Noemⁱ $

7 Thread ci rrentri read ( ) stop()

8 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA 9

10 * DESCRIPTION

11 * Agent Group disli jbuted clrics

12 *

13 * $Log /coir/ e tca/hsl/ ⁷ones]agents/col laborate/AgentGrouDlmpl ava S 14

15 * 7 10/01/96 ' 43p Noemi

16 * Added javadoc cc pine t^c

loσ c to

21 *

22 * 5 9/10/96 5 0^rp Noer-i

23 * Changed collaborate anc -na

24 *

25 * 4 9/06/96 3 33D ifoeiri

26 * Added removeAgert update^ς^nt and indexOfAσent r t ι^c "-»nq»ι

27 * addAge it ε argun-nt t^ ^r A~ent^rtt tuε ooiect 28

29 * 3 9/04/96 3 ι<ι, Noen 1

30 * Added αetCi upK τι mc c 31

33 * Turned on code _n constructor and fma.izer that 'eqi'-μ" a-d

34 * dereqisters ith tne RliI nare ^rerv»r 35

36 * 1 8/28/96 2 16D Noemi

37 * Basic synchronous agent collaboration functionality No supoort for

38 * remote groups cigen- mobility or asynchronous no ifications

39 */ 40

41 packaqe com raPitca 1 =^■ 1 zonesjaqent collaborate 42

43 import java util *

44 import java 10 *

45

46 import ava rmi serv^er Jπcas t emoteServer

47 import java rmi Re r Exo=pt- 1 on

Age-itGroupImpl. java_l Won Ncv 11 16:25:52 1996

48 import java. rmi Naming;

49 import java rmi Nr LLundExcestion, 50

Jl import java net Iret ". dre ^

'-2

53 /**

54 * AgentGrouplmpl s an RMI distributed object This is a base claεs

55 * that implements the Age-c roup interfaces 56

37 * Agents may bel no to one or more agent coordination groups

58 * (AgentGroups), »h:c act r.s focal points for distributed

59 * synchronous agent collaboration and asynchronous noti ications SO * (e g , exceptions) among members of the agent group

SI

62 * @see Agent

63 * @see AgentGroup

64 * Θauthor Noemi Pac-_or=k

65 */ 66

67 abstract public c^as-- AgentGrouplmpl

68 extends

69 implements AgentGroup { 70

71 // Constants

72 /**

^"3 * Default tιrr=out for c~l laborat ion m s

74 */

75 public static tiral long DΞFAUL1_TIME0UT = 100000,

76 // public stat. - -inal long DEFAU T_TIMEOUT = 5000 77

78

79 // Class varia. l^s

80 protected stat.c mt qrc DlD = 0,

81 '

82 // Instance vai .ables

83 protected long timeout, // collaboration timeout in ms

84 protected Stnrg groupName; // name to register with RMI Name Server

85 protected Vect r agentList, // Agent IDs of group members

86 protected Vector resultList; // results shared via collaborate

87 protected boolean ccllabora.ionlnProgress ,-

88

89 90 //Constructors 91 /** 92 * Constructs an AgentGrouplmpl object 93 94 " I

AgentGrouplmpl. java_l Mon Nov Jl 16:25:52 1996

95 public AgentGrcuplr.pl . ,

96 throws RemcteExcepcion {

}

^; o ς

100 /**

101 * Constructs an geπtGroucImpl object

102 * @param i eo Tne collaboration timeout in milliseconds 103

104 */ 105

106 public AgentGrc_.pImpl ( long .iraeout)

107 throws RemoteExcep ion { 108

109 this timeout = (timeout > 0 ) ~> timeout DEFAULT_TIMEOUT

HO agentList = new v e :>_ (>,

111 resultLiεt = null;

112 collaborat. jnlnProgress = false 113

114 /*

₁15 * Create a rame to represent this instance of an agent group

116 * and register it MΓ- the RMI name service

117 */

118 groupName - 'AgentGroup" + nextGroupID ( ) , ιl9 System out j irtln ( "gr cupName = " + groupName) 120

121 try { ι 22 Naming j < - mi (ci lUcName thu )

123 } catch (Ex' option e) {

124 System cut print In (" ^gentGroupImol can't rebmd ' * _e getMessage ( ) ) ,

125 e print =tackTrace ( )

126 }

127 }

128 ^: 129

130 // Finalizer .31 protected vo.d finalize!) _x32 throws Thrcvaole {

133 34 System out or m In ( "Age tGrouplmpl Finalizer called"),

135

136 // Remove t ns AgentGr -up ' s Name from the RMI registry

137 try {

138 Naming unbind (groupName) ,

139 ) catch (Exception ej {

140 Systerr out print lr ( 'AgentGrouplmpl can't unbind " + e getMessage ()) ,

141 print StackPrace M

AgentGrouplmpl. java_l Mon Nov 11 16:25:52 1996

142 }

143

144 super f me-.-.ze ( ) ,

145 } 146

147

148 // Class methods

149 private final ynchron zed int nextGroupID ( ) {

150

151 152

153

154 // Instance πet-o s

155 /**

156 * Returns the Agent Grcup's unique ID

157 * ^return the -qent Group s unique ID

158 */

159 public final String g=tCro,_pName ( ) {

160 return gr~ rN=m°

161 ) 162

163

164 I * "

165 * Converts an Acceⁿt Group nto its string representation

166 * @return A ^c _^g representing the Agent Group

167 */

168 public String >-~S πn * ,

169 return oro Hιm=

170 } 171

172

173 // Methods to -nr.pjlate rαent ist

174

175 /*^*

176 * Adds an Agent to the gr rup

177 * Θparam status The AcsntStatus object that describes the Agent

178 */

179 public synchronized void aodAgent (AqentStatus status) (

180 agentList addElement (status ) ,

181 System out -r intin (' Added Agent, ID = ' + status getAgentlDO +

182 ", St. i 's = ' ^■*^• status getStatuo() + ' to group")

183 ) 184

185 /**

186 * Locates arJ removes the AgentStatus object containing the specified ID

187 * Sparam aαent D An Age-t's unique ID

188 * ^exception Nι SuchEl=ιτ entExcept ion If the AgentStatus object doe=-

AgentGrouplmpl. ava_l Mon Ncv 11 16:25:52 1996 5

189 * not exist

190 */

191 public synchronized void rεmoveAgent (String agentID)

192 throws KoS chElementE>.-ept ion , ArraylndexOutOfBoundsException {

193

194 int index = _ndexOf ς° ^z (agent ID)

195 if (index -- 1)

196 throw - w Kc^c,jτ: ent Exceot ion ( "Can ' t f nd 'ι|ι^jntID")

197 agentList r crnoveElemen tAt ( index)

198 System oui cπntlnC Rera wed fger", ID - " + ag^nt:^{rι ■}* from qrnup' ) ,

199 } 200

201 /**

202 * Replaces t~ Agen Status object f^rr the specified IL

203 * This ethoo -ay be used to change an Agent's status TD or both

204 * Θparam ecentID An Agent's unique ID

205 * Θparam r-wStatus An AgentStatjs object to replace the existing one

206 * NoSuchElementE> cept on If the AgentStatuε object does

207 * not exist

208 */

209 public synchronized voic updateAgert (String agentID, AgentStatus newStatus)

210 throws NoSuchElementException, ArraylndexOutOfBoundsException {

211

212 removeAgen (agentID)

213 addAgent (rewStatus) ,

214 System out -nntln ( "Updated Agent ID from " agentID + " to New ID = ' +

215 new tat s cetA;c i¹- ID ( ) + ^ctatuε = ' ^■>^■ new^cfptuε qetStatusf))

216 ) 217

218 '*

219 * Walks the aner'L.it l -kmσ fci an AgentStatus ob]='-t with the

220 * specified ID

221 */

222 private .nt mnexOf Age- ( ^c tr mg eqertϊD) {

223 int index, numAgents,

224 for (index = 0, numAge-tε = agentList sized, index < numAgents, index⁴-!) {

225 AgentStatus status = (AgentStatus) agentList elementA ( ndex)

226 if (agentID corrpareTo (status getAgentlDO) — 0)

227 return index

228 }

229 return -1

230 }

231

232 /**

233 * Determines how many agents in the group have the εoecified status

234 * Θparam status The s^tatus value to search for

235 * Θreturn The number cf agent's with the specified rtatus

AqentGroupImpl. ava_l Mon No-j 11 16:25:52 1996 6

236 * @see Agen'Sratus

237 V

₂₃8 public int a jen tεWi th tat ι= ( int εtatus) {

239 int agen" = 0

240 for (Enu eration e = _c gentLiεt elements () e hasMoreElements ( ) ⁾ {

241 AgentStatus aStatus = (AgentStatus ) e nextElem=- t ( )

242 if (aSt-ituε getS-«.cus() == status)

243 ageιts++

244 }

245 return agent'

246 } 247

248

249 /**

250 * Returns the nunber of Ag»nts in the group

251 * dreturn "he number of _^ ents in the group

252 */

253 Dublic finao. irt getGrcucSize ( ) {

254 return st sited

255 256 257

258 '/ Methods to mplemen- co.laboration 259 260 261 Collaborate ( is fe p_blιc interface to collaboration It calls 262 beginCollabcration ( ) to synchronize the 263 and to a.t 'or all ac- ^r tc arrive 264 265 If all aα-n ration 266 point each zeResul ts ( ) 267 method to 268 269 Otherwise the agent tnat initiated the collaborate calls 270 recoverCc ^{^} _abτratιor ) 271 272 273 Θparam 'esult Th= result of the agent s c-mpjtatmn 274 Sexception i moteExcec ion If an error occurrs netting up network

275 * connections

276 * @exceptιc , AgentGroupException If the collaboration times out

277 * Oreturn An Obnect that describes the result of collaboration

278 */

279 public Ob ect collaborate ( AgentResult result)

280 throws Re-¹ teΞxcepti - AgentGroupException {

281

282 System ou_t F -ntln(' col Laborate RMI')

AgentGrouplmpl. java_l Mon Kov 11 16:25:52 1996 7

283

284 boolean f .rεtrd labors tor = begmCollaborat ion ( resul ) ,

285

286 /*

287 * If collc-bc-ati'-n failed and this is the agent that initiated

288 * collaboration, it woke up because its timer expired It retries

289 * once bef^ore ahro jp the other agents 290

291 */

292 if ( f lrstCc llaborεtor <_*& ' collaborationSucceed? ( ) ) {

293 Systerr out pr r'lnC'fciUiibn-'ririiin Tilled r t iyinq ")

294 synchroni zed ( ι_r i ) {

295 try <

296 this 'ai t ( imeout ) ,

297 } :tch ( InterruptedException e) { }

298 }

299 } 300

301 /^*

₃02 * If al_ agents m th e group have arrived at the collaboration

₃03 * point, =ar agent calls the applica ion-specific analyzeResul tr

304 * method to dete ii e the agent s next course of action

305 */

306 if (collah-rationSuccesdedO ) {

307 Syster- out pr±ntlr ( "Ready to do collabora ion'),

308 Object col laborati on = analyzeResul ts ( res l t ^rt elements!)) 309

310 /*

311 * The αert fa .mtiated collaboration c ars up

312 */

313 if (f-iSoCcllaccrator)

314 encCo.laboration ( ) , 315

316 return -'-.laborati-in

317 } elεe {

318 /*

319 * If th s is the agent that originated the collaboration,

320 * it v-,ke up becaise the timer expired It must wake up

321 * the other blocked agents (which are still sitting in

322 * beg- -Collabora e () ) and then recover from the error

323

324 if (iirstCcllaborator) {

325 System out prπtln ( "Collaboration Failed while " +

326 agentεWithStatus (AgentStatus INTRA SIT) +

327 ' agents wsre in transit"); 328

329 synchronized (t.nis) {

AgentGrouplmpl . ava_l Mon Ncv 11 16:25:52 1996 8

330 th„s notifyAllO,

331 )

332 rscoverCollaboration ( ) ,

333 } else

334 Ξvε teπ ou t o nt ln ( ' Col labora t ion Fa i l ed ' )

335 ^"

336 throw new AgentGro-pException (' Collaboration timed out"),

337 } 338

339 }

340

341

342 /**

343 * beginCollaboration ( ) is called internally by collaborate ( ) to

344 * synchronize each agent's recording of results and to wait for

345 * all agents to ari lve at the collaboration point This method acts

346 * as a distro-butel rendezvous, of sorts Each caller blocks until

34 * all agents _n the grouo have "arrived" at the collaboration point 348

349 * This method returns a ooolean that indicates if the agent initiated

350 * the collaboration

351 *

352 * Θparam re= .c Th= result of the agent's computation

353 * Sexception AgentGroupException If the group only has one member

354 * (ireturn A boolean indicating if the collabora ion was successful

355 *

356 */

357 protected synchr r ized bor lean ben inCol labor at ion (Aqenireru \ t remit)

358 throwε AgentGrouoE> cept ion { 359

360 boolean f _rstCol labor? or = falεe col laborat ion' )

364 if ( ' collaboraticnlr^r jgresε) {

365 /*

366 * It thiε agent is initiating the -ollaboration , allocate the

367 * resultLiεt Vector and add result to it Then wait for all

368 * agents to arrive at the collaboration point or for the

369 * collaboration timer to expire

370 V

371 i f ( _r gen tLι s t s i ze O < 2 ) {

372 en CoolaDorat LOΠ ( ) ,

373 tnrow new Agen GroupExcept ion (' AgentGroup too small")

374 } 375

376 coll jgreεs = true

AgentGrouplmpl. java_l Mon Nov 11 16:25:52 1996 9

37? f lrε_^CollaboratC- = true,

₃ 8 resU tlist = Victor (),

₃ 9 resuit ist addEl emant (result )

380

381 try <

382 tnis iai t ( time out )

386

387 /*

388 * id this agent's reεultε to reεultLi'-t If this is the

389 * last agent to arrive wake up the other agents Otherwise

390 * wait for the -ect of the agents in the grouo to arrive

391 */

392 resu.tList addElement (result )

393 if (co_ laborationS JΓ ceede ( ) )

394 ^~n_s notifyAIll)

395 else

396 tiy

397 this »a (

398 ^tc (In*-?' UDtedExcept ion e) { }

399 }

400 }

401

402 return f ι:f lia ^le^*- o

403 } 404

405

406 /**

407 * Cleans up af- " a s cces ul c"llab ration

408 */

409 protected vo - endCol labor at ion ( ) {

410 collabor or In^Dro"re=s = false

411 } 412

413

414 /**

415 * Cleans αp afte- a failed collabora ion

416 */

417 protected o c, . eccvarC^ llaborat ion ( ) {

418 endCo¹ laloiationO 419 420

421

442222 423

AgentGrouplmpl. java_l Mon Nov 11 16:25:52 1996 10

424 * anal zeRc= si lt= ( ) is an abstract method that must be overridden by

425 * each application It orovides the application-specific behavior

426 * requ.ref to implement collaboration This method is invoked on

427 * behalf ^f each agent i- the grouo It _ε passed the results

428 * computec \ each agen" and determines the courεe of action fo the

429 * calHng t-Or- t if anv based or th° computec resnl ε

434 */

435 abstract prot= t ³ Obn-c ^analyteKesul ts (Enume-at ion r sult*-) 436

437 /*

438 * Private method to dete.mme if all agents have reached the

439 * collaboration point li.s method is εynchronized tc prevent

440 * races iΛith agen^ts icni q and !-av.ng the qroup

441 */

442 private εynchronized bcole n col laboratιonSucceed°d ( ) (

443 return (reεultList s ϋ=() == agentList ειze())

444 }

445

446

447

448 /*

449^" * TURN ON LATER

450

451

452 // Methods tc hanαlc °x-ep ons a"d -ther notif cati n_^

453 piblic void α i^n E ceptιon(^ζμπn- anentID Ex'-ec. I r - t c)

454 thro Ret ^feE> "ti'i-r (

455 } 456

457 public void ag = " Termmati r(Strιrq aσentID)

458 throws Ren Exception '

459 } 460

461 * I 462 463 }

AgentResult. ava_l Mon Nov 11 16:25:52 1996 1

1 /* $Header: /com/mc- tca/hsl /. nesjagentε/collaborate/AgentResul t . java 4 10/01/96 3:43p Noemⁱ $

^{2 *}

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center America.

5 * All rights reserved.

1s ^* * CONFIDENTIAL AND PROPRIETA { PROPERTY OF MITSUBISHI ELECTRIC ITA.

8

9 * DESCRIPTION

10 * This object holdπ the esult of an acient's compu tions. 11

12 * $Log : /com/m i ea / hε 1 / zonesj agents /col laborate/AgentResul t . j ava $

13

14 * 4 10/01/96 3-.43p Noemi

15 * Added some javad-c comments 16

17 * 3 9/06/96 3-48p Noemi

18 * Added a protected default constructor to enεure that the public

19 * constructors . - ' v.c instance variables correctly. 20

21 * 2 8/30/96 4- 22p Noemi

22 * Changed private protected instance variables to pro^jected.

23

24 * 1 8/28/96 2 : l^"ϊp Noemi

25 * A generic class that represents the result of an agent computation.

26 * (Used by collaboration cede.)

27 */ 28

29 package co . ei t ca . hε 1. zoner gent s collaborate; 30

31 /**

32 * AgentResult co: tains an ;-.r;nt ID and a result tc be shared

33 * via collaborat i .in 34

35 * @see CollaboratorAgent

36 * @see AgentGrouplmpl

37 * dauthor Noemi Paciorek

38 */

39

40 public class AgentResult {

42 // Instance variables

43 protected String agentID: // ID of agent that computed reεult

44 protected Object reεult; // actual result computed

45

46 //Constructors

47 /**

AgentResul . java_l J-on Nov 11 16:25:52 1996 2

48 * Protected Default Constructor for an AgentResult object

49 * (Sexception X 1 legalAce=-ssFxoept ion Whenevpr called

50 */

51 protected AgentResul ( )

52 throws I ϊlegalΛcrerεEx rept ion {

53

54 System. out pr in lr (' Default constructor call'd foi AgentResul "),

55 throw new 1 legalAcceεsExcept ion ( " gentResul default constructor"),

56 } 57

58 /**

59 * Conεtructε an AgentResult object

60 * Sparam agentID The Agent's unique ID.

61 * @param remi The resilt to be shared via collaboration

62 */

63 public AgentResul (St ing agentID, Obnect result) {

64 this. agentID = ag-ntID

65 this result = res,: i

66 } 67 68

69 // Instance me t cds

70 /**

71 * Gets an Age^f" u"ic e ID from this AgentResult object

72 * Oreturn Ar -ce-t's -rique ID

73 */

74 public final String getAgentlDO {

75 return age: l^,

76 } 77

78 /**

79 * Gets the reεult to be snared via collaboratioⁿ

80 * from this AqentRes_^lt conect

81 * @return The esi.lt tc be εhared via collaboration

82 */

83 public Object getResultO

84 return result

85 } 86 87 }

AgentStatus. ava_l Mon Nov 11 16:25:53 1996 1

1 /* SHeader /com/ne tca/h_^l I zc leεnagent_^/collaborate/AgentStatuε java 2 10/01/96 3 44p Noemi $

² 3 ^** Copyright 1996 Foπzon Systems Laboratory, Mitsubishi Electric

4 * Information Te-nnolcgy Center America

5 * All rights leserved

7 * CONFIDENTIAL h Z PROPRIETARY PROPERTY OF MITSUBISHI FLECTRIC ITA

8 *

9 * DESCRIPTION

10 * Thiε object ho.dε an Agent s status (e g AClIvΞ)

11

12 * $Log /co τe tca/hεl/zones jagentε/collaborate/AgentStatus java $

13

14 * 2 10/01/96 3 d-.p Noemi

15 * Added some javacoc comments 16

17 * 1 9/06/95 3 ^"lp Noemi

18 * This claεε repr, =entε an agert ε current status (e g ACTIVE)

19 */ 20

21 packaqe com meitci hsl zones- agents collaborate 22

23 /**

24 * AgentStatus contains an agent ID and a status value Each ^gentGrouo

25 * contains ar Ag-nt^ctatus object for each Agert m the group 26

27 * @see Col labjrr tor gent

28 * @see AgentGrouplmpl

29 * Sauthor No=mι ^p _r p_r=>

30 */ 31

32 public class ^αen- S"atjε ^; 33

34 / / Conεtantε

35 pr i vate ε tat i c I -a l nt FIR T_^S^ATUS = 1

36 /**

37 * Agent lε active

38 */

46 */

47 public εtatic final int UNKNOWN = 3,

AgentStatus. ava_l Mon Nov 11 16:25:53 1996 2

48 private stat c final int ^ST_STATUS = UNKNOWN,

49

50 // Instance variables

51 protected Sf _ng agentID, // ID of agent

52 mt status // current εtatuε

53

54 //Construct!

55 /**

56 * Constructs =.n AgentStatjs object

5 * henr-ver called

58 */

59 protected Ai ^ntStatus ( )

60 throws _ _egalAccesεExceptιon { 61

62 System r t cr.ntln (' Default constructor called for AgentStatus"),

63 throw ne _ 1 _<=galAcceεsExcept ion ( " Agent^tatuε default constructor' ),

64 } 65

66

71 public AgentS^tatus (String agentID) {

72 this (agentID, ACTI\Ξ),

73 } 74 75 76 / * *

77 * Constructs an AgentStatus object

78 * @param agentID The Agent's unique ID

79 * @param ta s t e Ag_^nt s statuε

80 */

81 public AgentStatus (String agentID, mt status) {

82 this age-t D = agentID,

83 this stat is = ((status < FIRST_STATUS) | | (status > LAΞT_STATUS) ) ~

84 UNKN' Λ⁷N status

85 }

86 87

// Instance rd"

89 / **

90 * Extracts an Agent'ε umq> ID from an AgentStatus object

91 * Oreturn An Agert's uniqe ID

92 */

93 public final jti iπq qc t / κ> tID() (

94 return a- ^3t-tID

AgentStatus. ava_l Mon Nov 11 16:25:53 1996 3

95 }

⁹ 97⁶ /**

98 * Extracts an Ac-mt's curr snt εtatuε from an AgentStatuε object

99 * Sreturn An <λg<-t ε cαrr-nt statuε 100 */

101 public final t getStatuε ( ) <

102 return statu«

1 03 } 104

105 }

CollaboratorAgent. ava_l Mon Nov 11 16:25:53 1996 1

1 /* SKeader /com/nei cca/h= 1 'zones_jagents/collaborate/CollaboratorAgent java 5 10/01/96 3 45p Noemⁱ $

2 3 ^** Copyright 1996 Horizon Systemε Laboratory, Mitsubishi Electric

4 * Information Technology Center America

All rights reservpc

7 * CONFIDENTIAL & ^"D PROPRIETARY PROPER'!/ OF MITSUBISHI ELECTRIC ITA

8

9 * DESCRIPTION

10 * Derived claεs fri nobije Ag-nt ^rc 1 laborat ion 11

12 * $Log /co-/ τιeι tca/hsl /zones jagentε /collaborate 'Col laboratorAgent java $ 13

14 * 5 10/01/96 3 45p Noemi

15 * Added some javad~o com ent 16

17 * 4 9/20/96 4 Ito Noemi

18 * Changed finalizer to ensure that it performs cleanup nc more than once

19 * ( A bug the ga baqe '-cllector may cause the final itt-r to be called

20 * mr re than once') 21 2^'2 * 3 9/10/96 3 OΪ-D Noemi

23 * Renamed εe Intrans _^tStatuε and εetAct lveStatuε to preoare^orTranεport

24 * and completedTra^εoor r=scec"ιvely

25 *

26 * 2 9/06/96 3 57p No -i

27 * Added tie fcllovi.ng Sta tuε

28 * f»t I tra"sι t ^ t j 29

30 * 1 9/04/96 3 _~o Noemi

31 * Suoclass of Aqent that ιmcl=nents a c_^llabcratmq Aqent 32

33 */

34 package r-om meitca h=l zones agents collaborate 35

36 import java util *,

37 import java net 38

39 import com meitca hε_ z ~nes jaσents shared Agent 40

41 /**

42 * A subclass of Agei t that enables collaboration among aqents in a qroup

43 * Agents wishing to ollabcrate must extend this class to do some useful work

44 * They must also b- ong to an agent coordination group (AgentGroup) Generally,

45 * an application fi- cr=ar»ε an AgentGroup Then it obtains a reference to

46 * the RMI interfac ror "e nroup by looking up the group in the local RMI name

47 * service Subεeqi :- ly, it creates new CollaboratorAgents and populates the

CollaboratorAgent. ava_l Mon Nov 11 16:₂5:53 1996 2

48 * group with them (by passing the contructor a reference to the interface) 49

50 * Ssee Agent

51 * Ssee AgentGroup

52 * @author Noemi Paciorsk

5 */

54 public abstract claεr CollaboratorAgent

55 extends Agent 56

57 // Instance- variables

58 protected ec or group .εt; // AgentGr ups this agent belongε to 59

60 // Conεtructorε

61 /**

62 * Constructs a CollaboratorAgent

63 * Sexcept.on IllegalAccessException Whenever called.

64 */

65 protected Col labr vatorAgen ( )

66 throws I l l ecia „Acc<?εεEκo=pt i on { 67

68 System. out . println ( "Default constructor called f r CollaboratorAgent");

69 throw new I 1 egalAcceεsΞxception ( "Col laboratorAgent Default constructor");

70 } 71

72 /**

73 * Constructs a CollaboratorAgent

74 * @param grr-up The AgentGroup to which this Ag°nt belongε.

75 */

76 public Ccl . ahc.rat^r Ag÷^_.t (AgentGroup group) ' 77

78 * Store a copy of the agentID in the AgentGroup and save a

79 * reference to the AgentGroup in groupLiεt.

80 ^*/

81 groupList = new Vector ();

82 addGrou (group) ;

83 } 34

35

86 /**

87 * Constructs a CollaboratorAgent

88 * ?param grcups A list of AgentGroupε to which this Agent belongε. 39 */

90 public CollaboratorAgent (Vector groups) {

91 thiε (groups, null);

92 }

93

94

CollaboratorAgent -java_l Mon Nov 11 16:25:53 1996 3

95 /**

96 * Construe ε a Col lsocratorAgent

9 * Θparam groupε A list of AgentGroups to which this Agent belongε.

98 * θparam oidID Th-s unique ID of an agent to be replaced by thiε agent.

99 */

100 public Col -dboratorΛge it (Vector groups, String oldID) {

101 /*

102 * Sa ,r a copy of agentID in each cf the aεsociated AgentGroups and

103 * sto"-- a reference to each AgentGioup in groupLift

104 */

105 groupLiεt r ^jw Vect irO ,

1C6 for (Enumeration e = groups elements(); e hasMoreElements ( ) ; ) { 107 AgentGroup group = (AgentGroup) nextElement ( ) , i 8 gr-uplist addElement (group) ,

I^1'' 9

110 try

111 _f (oldID == null)

112 gr p addAgen (nerf Age- tStatuε (agent ID) ) , .13 "lεe

114 group jpdateAgen (oldID, new AgentStatus (agent ID) ) ,

115 Syεtem cut println ( "Group εi∑e - " ι group σetGroupSi ze ( ) ) ,

116 } catch (Exception ex) {

117 ^System out println ( "Agent construct cu can't add agent to group " +

118 ε>. g-t,":essage ( ) ) ; 219 System. ou .println ( "AgentID = " + agentID + ", oldID = " + oldID) ,

120 ex pπntStackTrace ( ) .

121 } 122

123 )

U4 }

125 126

1..7 // Finalizc-

_±28 protected void finph∑el)

129 throws Thrc.arle { ι30

131 System out cπntln ( " Col laboratorAgent Finalizer called") ;

132

.36 if (grc .lp^'oist '= mil) {

137 for .Enumeration e = groupList . elements () ; e .hasMoreElements () ; ) {

138 AgentGroup group = (AgentGroup) e . nextElement () ; 139 try {

140 group re oveAgen (agent TD) ;

141 ) catch (Exception ex) (

CollaboratorAgent. java_l Mon Nov 11 16:25:53 1996 4

142 Syεtem out println ( "Col laboratorAgent finalizer- can't remove agent from group

143 ^' ex getMessage ()) ,

144 e>- r --ι-ι StackTrace ( ) ,

145 }

146 }

14 groupL_=t = null // in case finalizer gets called twice (it has been^{1 )}

148 }

149 super linalizeO ,

150 } 151

152 // Instance- nethods

153 /**

154 * Returns a ust of groups the Collaborator gent belongs to

155 * (?return The .ist o*^" groups th s CollaboratorAgent belongε to

156 */

157 public final cynchrc-i zed Enumeration getGroupε ( ) {

158 return groupList elements)),

159 } 160

161 /**

162 * Add a group to this agent's groupLiεt and add the agent 163 * to the σioup's agent list 164 * Θparam group The group tc be added 165 */ 166 public sync hromzed void addGroup (AgentGroup group) { 167 grotpL.^t addElement (group) 168 169 try 170 grc addAg - ( iΛ AgentStatuε (agentID) ) 171 Syεtem out pri"¹ tin ( "Group εize ( ) ) , 172 cf ter (Exception , x) { 173 Syεtem out pr inzln ( ' Can ' t add agent to group ' + ey getMessage () ) 174 ex Di-i-itStacKTrace ( ) , 175 176 177 178 /'

186 try {

187 gr.,up removeAg- it (agentID) ,

188 } catch (Exception ex) {

CollaboratorAgent. java_l Mon Nov 11 16:25:53 1996 5

189 System out p i^tln ( "Can ' t remove agent from group " + ex getMessage 0) ,

190 ex pr intStackTrace () ,

191 ⁾

192 }

193 194 195 /**

196 * Upcate in agent ^■- citus in all group' it b^lrni*- to

197 * @param status Th= new εtatus

198 */

199 public synchronized oid updateStatuε ( mt status! {

200 if (groupList '= null)

201 for (Enumeration e = groupList elements!) , e hasMoreElements ( ) , ) {

202 AgentGroup group = (AgentGroup) e nextElement () ,

203 try {

204 grouo updateAgent (agent ID, new AgentStatus (agent ID, status)) ,

205 } catch (Exception ex) {

206 System nut print In ( "Col laboratorAgent finalizer can't remove agent from group

207 ex getMesεage ( ) ) ,

208 ex pn itStackTraceO , 209

210 }

211 } 212

213 /**

216 public void preua r-=ForTran?port ( ) {

217 updateStatuε 'AgentΞtat.ε ΪNTRANSIT)

218 } 219

220

221 / * -

222 * Set a- agent •- ^s atus to ACTIVE after tranεport

223 */

224 public void cc~ipietedTranspcrt ( ) {

225 updateStat„ε (AgentStatus ACTIVE),

226 ) 227

228 }

EventException. ava_l Mon Nov 11 16:26:41 1996 1

1 /_* SHeader: /com/mei tca/hsl /zonesjagents/event /EventExcep ion . Java 1 10/14/96 6:55p Noemi $

2 *

3 * Copyright 199c Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center .America.

5 * All rights reserved. 6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA.

8

9 * DESCRIPTION 10 * Event exceptions 11

12 * SLog : /cort./meitca/hεl/ zonesjagents/event /EventExcept ion . java $ 13

14 * 1 10/14/96 6:55p Noemi

15 * Base class for exceptions generated during event processing.

16 */

17 package com. eitca i-si . zoneεj gents . even ; 18

19 /**

20 * Exceptionε encountered by Events. 21

22 * @see EventType

23 * Sauthor Noemi Paciorek

24 */ 25

26 public class EventException extends Exception { 27

28 // Constructors

29 /**

30 * Constructs an EventException.

31 * Sexception IllegalAccessException Whenever called.

32 */

33 protected EventExcept ion ( I

34 throws 11 l-OJ-.lAccoεεΞ.-.cept i cr. ( 35

36 System. out p intln ( "Defaul constructor called fι-r EventException");

37 throw new IllegalAccessException ( "EventExcep ion Default constructor");

38 } 39

40 /**

4 1 * Cons t r uc t s fi n F'vi -n I [^■ yc-: -. i on .

42 * taparam tyc e A st r i ng descr ibi ng the except i on .

43 */

44 public EventEx: ept ion (String type) { 45 super (type) ;

46 l 47 }

EventGroup. java_l Men Nov 11 16:?6:41 1996 1

1 /* SHeader- /com/nr-itca/hsl/zc .=s jagents/even /EventGroup ava 1 10/14/96 6:59p Noemi S 2

3 * Copyright 199 f Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Tec nr.o logy Cent, r America

5 * All rights reserved 6

7 * CONFIDENTIAL AXO "'RCPRiπTA"" PFOPF.RTY OF MITSUBISHI ELECTRIC ITA 8

9 * DESCRIPTION

10 * Event Group d stribu ed inti ifac

11

12 * SLog: /cor, "ei tca/hsl /zonesjagents/event 'EventGroup . -java $

13

14 * 1 10/14/96 6.59p Noemi

15 * Event Group interface. 16

17 * I 18

19 package com meitca hs_ z^ne iag^nts event, 20

21 import Java util .^'- SuchElementExcept ion ; 22

23 import Java . rmi . Remot ;

24 import Java rmi Remci eException

25 ^"

26 /**

27 * EventGroup is =ι : "tribated l-'I interface for event croups 28

29 * An EventGroup -r-εiεts f a cioup of objects that v. ; c h 'c receive

30 * events generated by the oth - members of the group The EventGroup

31 * serves aε a gate i?.y between the objects in the group and forwards

32 * events posted tc it to the -r mbers of the group. 33

34 * The members of tr>- group muε- all implement the EventPost interface 35

36 * @see EventGroupImpl

37 * ^author Noemi Faciorek

38 */

40 public interface EventGroup

41 extends Remot-» ,

42

43 /**

44 * Addε a memcer to the event croup.

45 * Spara orrnect An Object that implements the EventPost interface.

46 * @exception i noteExc ept on Tf an error occur ]■- -' t t i cig up network

47 * connections

EventGroup. java_l Mon Nov 11 16: -.6:41 1996 2

48 * Sexception "lassCaεtExceotion If ob₃ect does not implement EventPost

49 */

50 public void aάo^vember (Cb₃ec¹ ob₃ect)

51 throws Remc teFxc=pt ion "laεsCastExcept ion 52

53 /**

54 * Removes a me^mber from tne group

55 * Θparam ob;ect The Object to remove

56 * Sexception Remote >cept _on If an error ticcurr' ^ccttιng up networl

57 * connections

58 * Sexception n uchElemen Exception If ODJM t is not a member of the group

59 */

60 public void ren-veMe oer (Oo ct object)

61 throws Rer teException, iJoSuchElementException 62

63 }

ZventGroupIn.pl. java_l Mon Nov 11 16:26:41 1996 1

1 /* SHeader- /com, meitca/hsl/zoπas-jagents/event /EventGroupImpl . java 2 10/22/96 7-10p Noemi S

2

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information T=~hnology Center America

5 * All rights leserved 6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8 *

9 * DESCRIPTION

10 * Event Group di^stributed obje t

11

12 * SLog I con -e i tc a /hs l / zces j agents , event /EventGroupImpl j ava $

13

14 * 2 10/22/96 ^"" lOp Noemi

15 * Changed the thr ε claαεe of the poεtEvent method 16

17 * 1 10/14/96 59p Noemi

18 * Event group lmp-ementat on 19

20 */ 21

22 package com ire i tca nsl conesjage- ts e vent ,

23

24

25 import java util *

26 import ₃ava io *, 27

28 import ]ava rmi seivi-r

29 import ₃ava rmi RemoteException

30 import ₃ava rmi Namrg,

31 import ₃ava rmi All e=> y3oαndΞ'> -eotion 32

33 import com meitca -si util UniquelD 34

35 /**

36 * EventGroupImpl -ε an R'I disti .tuted object that implementε

37 * Event Group and EventPoεt

38 *

39 * An EventGroup consists of a yrjup of cbjects that wish to receive

40 * events generated by the other members of the group The EventGroup

41 * serves as a gateway between -he objects in the group and forwards

42 * events posted t' i to the members of the group

43 *

44 * The members of the group must all implement the EventPost interface

45 *

46 * @see EventGroup 47 * Sauthor Noemi Pjcυ rek

EventGroupImpl. ava_l Mon Nov 11 lb:₂6:41 1996 2

48 */

49

50 public class EventGrc^pI p_^

51 extends UnicastRemoteServer

52 implemen-s EventGroup Fvent^oεt {

5

54 // Instance

55

56 /** A list of t le group's meTbers */

57 protected Vect r memberList 58

59 // Const-uctor

60 /**

61 * Constructs an ΞventGrouc_-Ol object

62 * Sexception R<=mot=Εxcept_ n If an error occurrs '-etting UD network

63 * connectionε

64 */

65 public EventGroupImpl ( )

66 throws Rer^teExcept ion

67 /*

68 * Create membe¹' ' 1st air event queue

69 */

70 memberList - new \ector )

74

75 / FvoηtG-oup " c -

76 /"

77 * Add a me ber t~ the eve-_^t grojp

78 * Oparam o„ ect An Object that implements the Eve¹t^Dost interface

79 * no¹- molement EventPost

80 */

84 try {

85 Event^Post eventPost - (EventPost ) oL ect

86 } catch (C.aεsCaεtExceotion e) {

87 Syεter out pπntlnC . JdMember Object does no^f imolement Event Post')

88 throw

89 }

90 memberLi ' L addEl emen t ( obj ^ct )

91 92

93

94 / * *

EventGroupImpl. ava_l Mon Nov 11 16:₂6:41 1996 3

95 * Remove a member fro;τ the group

96 * Θparam object The Object to remove

97

98

99 p 100 throws NoSuchEleτien tExcept ion { 101

102 if ('memberLi-t re veElement (ob ect ) )

103 throw new NoSuchElementException ( "Object not member of group')

104 } 105 106

107 // EventPost methods

108 /**

109 * Forward an event tc all members of the group

110 * Sparam event The event to oost

111 * FventEx-ept ion I* an error occurs r"s<-ιng the event

112 */

113 public void postLvent (E entType event)

114 throws RemoteExcep ion EventException I0Ξ> ~er " i n { 115

116 for (Enuneratic- e = memberLiεt elements () e hasMoreElements ( ) ) {

117 EventPost event ueue = (EventPoεt)e nextElement () ,

118 eventQueue postEvent (event )

119 }

120 121 122 }

EventHandler . j ava_l Mon Nov 11 16:26:41 1996 1

1 /* SHeader /com/me Ltca/hsl 'zonesjagents/event/EventHandler java 1 10/14/96 6 56p Noemi $

² 3 ^** Copyright 1996 Hoπzo-i Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center America

5 * All rights u serveα

7 ⁶ *^* CONFIDENTIAL AND PR^OPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8 *

9 * DESCRIPTION

10 * Event handler interf ace

11 *

12 * SLog /com/meit a hsl/zoneεjagents/event/EventHandler java $ 13

14 * 1 10/14/96 6 5Sp Noemi

15 * Event handler interface

16 */ 17

18 package com meitca -Si zonesiagents event

19

20 import Java rmi Remcte

21 import java rmi RemcteE ceotion

22

23 /**

24 * EventHandler is a distributed RMI interface for handling events

25 *

26 * "author Noemi "acicek

27 */ 28

29 public interface Even^*-Ha idjεr { 30

31 // Instance methods

32 /**

33 * Event handler

34 * θparam event Current event

35 * Θexception F-^-no ,-~xceptιon If an error occurrs setting up network

36 * connections

37 * ©exception Ξve-itExceotion If an error occurs handling the event

38 */

39 public void hardleEvert (Ei/entType event)

40 throws RemoteExceoticn EventException

41 }

42

EventManager. java_l Mon Nov 11 16:26:41 1996 1

1 /* SHeader /com/meitca/hsl/ zonesjagents/event/EventManager Java 2 10/22/96 7 12p Noemi S

2 *

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Teτι ology Center America

5 * All rights reserved s ^*

7 * CONFIDENTIAL AJΛT PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8 *

9 * DESCRIPTION

10 * Event Manager Int t. fac

11 *

12 * SLog /com/meitca/rεl/ zcreεjagentε/event/EventManager java S 13

14 * 2 10/22/96 7 _2p Noemi

15 * Changed registerEvents and unregisterEvents to take an array of

16 * Strings, rather than an ai-ray of EventType Also changed several of

17 * the throws clauses

18 *

19 * 1 10/14/96 6 58p Noemi

20 * Event Manager interface

21 */ 22

23 package com meitca r=l zonesjagents event 24

25 import java 10 *

26 import java rmi Rer>~te

27 import ava rmi Reir- teΞxcep ion 28

29 /**

30 * EventManager is a distributed RMI interface for event management 31

32 * Θsee EventManager Impl

33 * "author Noemi Pa- orek

34 */ 35

36 public interface EΛ entManager

37 extends Remote { 38 39 // Instance metnods

40 / / Methods useα to regi s ter mtereεt m spec i f ied events

41

EventManager. java_l Mon Nov 11 16:26:41 1996 2

48 * connections

49 */

50 public void registerEvents (String events [] , EventPost eventQueue)

51 throws RemcteExceoticn, IOExcention ;

54 * Reσ —iεter interest 1- receivmc— all events ooεtec to th s Even_tManager

55 * dpararn ever Queue The associated event queue's EventPost interface

56 * ©exception RemoteException If an error occurrs setting up network

57 * connections

58 */

59 public vcid rec sterAll (EventPost eventQueue)

60 tnrowε RemoteException, IOException, 61

62 // Metnods to ur.regiεter events

63 /*"

64 * Remove registration for specified events

65 * Spara evsnts A.-, array cf tne names of events that an ooject

66 * is no longer interested in receiving.

67 * @param evs-tQueue Tne associated event queue's EventPost interface

68 * ©exception RemoteException If an error occurrs setting up network

69 * connections

70 * ©exception EventManagerException If the event queue was not registered

71 * for one or tore of the specified exceptions

72 */

73 public void unregiεterEvents (String events [], EventPost eventQueue)

74 throws RemoteException, IOException, ΞventManagerΞxceoticn ; 75

76 '**

77 * Remove registration for all events.

78 * Sparam eventQueue The associated event queue's EventPost interface.

79 * Sexception RemoteException If a- error occurrs setting up network

80 * connections

81 */

82 puolic void um sg εterA.ll (EventPost eventQueue)

53 throws RemoteException, IOException; 84

85 }

EventManagerException. java_l Mun Nov 11 16:₂6:41 1996 1

1 /* $Header /com/meitca/hsl/ zones₃agents/event/EventManagerExceptιon ₃ava 1 10/14/95 6 57p Noemi $

2 *

3 * Copyright 1996 Horizon Systems Laboratory, Mitεubiεhi Electric

4 * Information Technology Certer ^erica

5 * All nghtε reεervec

⁶

1 * CONFIDENTIAL AND ^ROPFIETARY PROPERTY OF MITSUBISHI ELECTPIC ITA

8

9 * DESCRIPTION

10 * EventManager excec^ιon=- 11

12 * $Log /com_/ ι- _ tea/ εl zoneε₃agentε/event/EventManagerExceptιon ₃ava $ 13

14 * 1 10/1^/96 6 57p Noemi

15 * Exceptions generated by the Event Manager

16 */

17 package com meitca hεl zoneε-agentε event 18

19 /**

20 * Except i ons encoun t ered o\ the EventManager

21 *

22 * @see EventMangei Irol

23 * ©author Noemi Pac orek

24 */ 25

26 public class EventManagerExceotion extends EventException { 27

28 // Constructors

29 /**

30 * Constructs <r>n EventManagerExceotion

31 * ©exception - ¹ leqa¹ ! cc ^εεEx'-e tion Whenever called

32 */

33 protected EventManagerException ( )

34 throws Il_egalAcceεεΞxceptιon { 35

36 System out println (' Default constructor called for EventManagerException"),

37 throw new I I.egalAcceεεException ( "EventManagerExceotion Default constructor")

38 }

39

40 /**

41 * Constructs an EventManagerException

42 * Θparam type A String describing the exception

43 */ •

44 public EventManagerException (String type) {

45 super (type)

46 }

47 }

EventManagerException. java_l Mon Nov 11 16:26:41 1996

48 49 50

51

EventManagerlmpl. ava_l Mon Nov 11 16:26:42 1996 1

1 /* $Header /com/neitca/hsl/zones₃agents/event/EventManagerImpl ₃ava 3 10/24/96 4 ^• 57p Noemi $

2 *

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center America

5 * All rights reservec

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

8 *

9 * DESCRIPTION

10 * Event Manager c_εtrιbated object

11

12 * $Log /com/meitca hsl/ zont =₃agents/event/EventManager Impl ₃ava $

13

14 * 3 10/24/96 4 57p Noemi

15 * Added support fcr an Event Manager propertieε file and propertieε that

16 * specify if persistence is =~abled and the name of the persistent

17 * εtorage file

18 *

19 * 2 10/22/96 ~ 28p Noemi

20 * Save full and specific event registrations to perεiεtent εtcrage

21 * Constructor reads pers.stent data and reconstructs noti ications

22 * EventManager rercves evert queues that it can t post events to

23 * Changed registerEver ts and unregisterEventε to take an array of String

24 * Made constructor protected and added a main method

25 * Perform cleanup I'-PΓ receiving conflicting registrations (full vε

26 * specific)

27 *

28 * 1 10/14/96 6 58p Nceτι

29 * The Event Managei

30 */ 31

32 package com meitca ^εl zcneεjagents event

33

34 import java util *

35 import ja a io *

36

37 import ₃ava rmi server Unicaεt emoteServer

38 import ]ava rmi RemcteE -.cept ,01

39 import ]ava rmi Nan ing ,

40 import ₃ava rmi NotBcundExcept ion ,

41 import ]ava rmi Alreadv BoundFx~eptιon

4^2 ^'

43 import com meitca hs_ zoneεjaqentε εhared *

44

45 import com meitca hεl zoneεjagentε εecurity InsecurityManager 46

47

EventManagerlmpl . j ava_l Mon Nov 11 16 : 26 : 42 1996 2

48 /**

49 * EventManagerlmpl xS an Event Manager that implements the RMI

50 * EventManager and E^entPoεt interfaces

51 *

52 * This class allovε objects to register their interest in receiving

53 * specified events and to ael=te their registrations

55 * Ob_jects Dost events by calling the EventManager s poεtEvent method

56 * (defined by the E^enfo't interface) 57

58 * The EventManager „=; a scntn = l object (l e there is only one

59 * per system 60

61 * @see EventManager

62 * @see EventPost

63 * @εee EventHandler

64 * @see EventManage.. Proxy

65 * @author Noemi "ac_ore>

66 */ 67

68 public clasε Event anager Impl

69 extends UnicastRenoteServer

70 implements EventManager Ξ.enfost { 71

72 // Constants

73 private static __-al Strmc EvENT_MAN^GEP_ AME = EventManager' 74

75 private εtatic :mal String PRO^DERTIES_DESCFIPTION = Propertieε File for EventManager

76 private εtat-c final Sfiig ENAB E_PEPSISTE CE = EventManager Derεiεtence Enable

77 private static final String PERSISTENCE_FILE = EventManager persistence FileName'

78 // private static final String DEF?ULT_PERSISTENCE_FILE = 'C \ \temp\ \EventManager store

79 private εtatic fmal String DΞFAULT_PΞRSISTENCE_^C,ILE = EventManager store 80 81

82 /* IDs for persis e-^*" oc-e ts */

83 private εtatic final mt EVΞNT_REGISTRATION_ID = 1

84 private stat.c f.nal mt FJ L_REGISTRATION_ID = 2 85 86 private static .nal li ST RAGE_PADDING = 1024,

89 // Instance variables 90

91 /**

92 * Hash table that maps class names derived from EventType to

93 * registered Eve-ifost stubs

94 */

EventManagerlmpl. java_l Mon Nov 11 16:26:42 1996 3

95 protected Hashtabie eventRagistrations ,

⁹ 97⁶ /** List of EventPost stubs registered to receive all notifications */

98 protected Vector fullRecistrations ,

99

104 */

105 protected Hashtab.e evenlU _ι f icat ιon^< 106

107 /** A reference to tmε EventManager ' s persistent store handler */

108 protected PerεistentStoreHandler persiεtenceManager 109

110 /** Name of the persistent storage file */

111 protected String persiεtentStoreFile 112

113 /** The properties file */

114 protected JASProperties properties,

115

116 // Constructors

117 /**

118 * Constructs an EventManager EventManagerlmpl has no public

119 * constructors Applications wishing to utilize the Event Manager's

120 * services must access _t via EventManagerProxy

121 */

122 protected EventManager rn-^1 ( )

123 throws Ξxcec ion { 124

125 /*

126 * Locate oro ertieε file

127 */

128 try

129 properties = new JASProperties (EVΞNT_MANAGER_NAME,

130 JAS^Properties SERVER, PROPERTIES_DESCRIPTION, false),

131 System cut println ( "EventManagerlmpl Located properties file") 132

133 } catch (Exception e) {

134 System out println ( "EventManagerlmpl Couldn't access Propertieε file for Conduit S

135 System out println (' with defaults ")

136 // Construct an empty Properties object

137 properties = new JASProperties () ,

138 )

139

140 /*

141 * Recover -vent av- fu.l registrations from storage,

EventManagerlmpl. ava_l Mon Nov 11 16:26:42 1996 4

142 * if required Then reconstruct event notif icat lonε

143 */

144 recoverRegiεtrationε ( ) ,

145

146 /*

147 * Register this instance with the RMI registry

148 */

149 try {

150 Naming reomd (EVENT_MANAGER_N<ΛME, this),

151 } catch (Exception e) {

152 System out println ( EventManagerlmpl can't bind " + EVENT_MANAGER_NAME + " " + e getMessage () )

153 e .printStackTrace ( )

154 throw e,

155 }

156 } 157 158

159 // Finalizer

160 /**

161 * Removes the tventManager ' s entry from the RMI registry

162 */

163 protected void -.nalizeO

164 throwε Thro^able {

165

166 System. out println ( "EventManagerlmpl Finalizer called"), 167

168 // Remove this Ξvent'ls l r ' ε Name from the RMI regiεtry

169 try { 170 Naming . unbind ( EVΞKT_KANAGER_NAME ) ,

171 } catch (Exception e) (

172 Syεtem out println ( EventManagerlmpl can't unbind " + e getMessage!) )

173 e printStackTrace ()

174 } 175

176 // Delete re^ference to Persistent Store Manager

177 persistence!'?, nager = n_ 1, 178

179 super finalize ( . ,

180 } 181 182 183

184 // Instance methods

185

186 // Methods to add event registrations

187 /**

188 * Register interest in receiving specified events

EventManagerlmpl. java_l Mon Nov 11 16:26:42 1996 5

189 * To remove these registrations use

190 * unregisterEvents (EvencType events [] , EventPost eventQueue) 1S1 * clparam events ?-n array of the names of events that an object

192 * is interested in recε.v g

193 * @param eveni Queue The associated event queue's EventPost interface

194 V

195 public synchronised voic regiεterEvents (String eventε[], EventPost eventQueue)

196 throws IOException { 197

1°8 /*

199 * If the event queue nas already regiεtered to receive all

200 * notifications, ignore this request

201 */

202 if ( fullRegistratiorε contains (eventQueue ) )

203 return 204

205 /*

206 * Get the list of e^ rtε the queue has registered

207 * for not- neat ion If the list doeε not exiεt create it

208 */

209 Vector not.fi List = (Vector ) eventNotif icat lonε q=t (eventQueue) ,

210 if (notifyLifct == null) {

211 notιfyLι=t = new vector ()

212 eventNc t i f icatio-ε out (eventQueue , notifyList)

213 }

214

215 for ( t 1 = 0 l < ev≡ntε length 1 +- ;

216 String eventName = ^jventε[ι],

217 System out pnntl-( re iεterEventε event = ' ^■*^■ eventName) 218

219 /*

220 * Add ev t t - the σ„eue ε list of registered events

221 */

222 if ('n.tifyLiεt containε (eventName) ) {

223 Syεtem out pr ι- tin ( ' registerEventε adding event name to notify list"),

224 notnyList aαoΞlement ( eventName) ,

225 } 226

227 /*

228 * Look up the event name in the eventRegistrations hash table

229 * and add the queue to the list of regiεtered Objects for the event

230 */ ^'

231 Vector registryList = (Vector • eventRegiεtrat i onε qet (eventName) ,

232 if (registryList == null) {

233 regιεtryL_εt = new Vector (),

234 eventRegistrations put (eventName, registryl ist ) ,

235 System out pi m In (' registerEventε , adding pvnnt queue to registry lι*-t')

EventManagerlmpl. java_l Mon Kov 11 16:26:42 1996 6

236 registrvL.εt εddElement (eventQueue) ,

237

238 } else if ('registryList contains (eventQueue) ) {

239 Syεtem out println (" registerEvents, adding event queue to registry list')

240 regiεtrvL ct _c odElement (eventQueue)

241 }

242 }

243 /*

244 * Write the ~ooated e.°ntRegιstratιons table to

245 * persistent storage

246 */

247 updateEventReg.strations ( )

248 } 249

250

251 /**

252 * Register interest receiving all events posted tc thiε EventManager

253 * To remove the== reg.str jtions use

254 * unregiεterAl. lEventPcs*- eventQueue)

255 * @param evntQueue Pn= associated event queue s EventPost interface

256 */

257 publ ic synchronize: JΌ I O =cι ε terAl 1 ( EventPoε t <=ventQueue )

258 throws IOEx-eot ion {

259

260 System out prι"tln( reg_sterAll ' ) 261

262 /*

263 * If this event queue already registered to receive

264 * specific l egistratio is remove them

265 */

266 if ( (Vector) eventNot . r ications get (eventQueue) '= null)

267 unreg. s ti rAl l ( ev en^tQueue ) 268

269 /*

270 * If the event queue n_ds already been registered for

271 * all noti^fications ignore this request

272 * Otherwise add t e q_.eue the the list of full registrations

273 */

274 if ( ' fullRegiεtrations contains (eventQueue) ) {

275 System out println) regiεterAll, adding event queue to full registrations')

276 fullRegistrationε audElement (eventQueue)

277 /*

278 * Write the updated fullRegiεtrations list to

279 perε_stent εtorage

280 */

281 updateF_llRegιεtrat-onε ()

282 }

EventManagerlmpl. java_l Mon Nov 11 16:26:42 1996

283 } 284

285

286 // Methodε to r-nove registrations

287

288 /**

289 * Remove registration for specified events

290 * Sparam events An array of the names of events that an object

291 * is no longer interested in receiving

292 * @param eventQueue The associated event queue's EventPost interface

293 * Sexception EventManagerException If the event queue was not registered

294 * for one or rore of the specified exceptions

295 */

296 public synchronized voiα unregisterEvents (String events [] , EventPost eventQueue)

297 throws EventManagerException, IOException { 298

299 /*

300 * Get the ..st of events the queue has registered

301 * for rot.ticatior

302 */

303 Vector = ( "ector ) eventNotif ications get (eventQueue) ,

304 if (notifyLiεt == null)

305 throw r=w EventKa "lagerException ( "Bad event queue");

306

307 for (mt l = 0, l < events length ι ++) {

308 String eventName = events [l],

309 Syεtem cut pπ-tl- ( "unreg.sterEvents event = ' + eventName), 310

311 /*

312 * Remote tne event from the queue ' ε list of regiεtered events

313 */

314 System out println ( "unregisterEvents, removing event name from notify list"),

315 notifyL.εt re-ioveElement (eventName) 316

317 /*

318 * Look up tne event name in the eventRegiεtrations hash table

319 * and remove the queue from the list of registered Objects for

320 * the event. If tne list is empty, remove the event's hash

321 * table entry

322 */

323 Vector registryList = (Vector ) eventRegistrat ions get (eventName) ;

324 if (registryL.st == null)

325 throw new EventManagerException ( "Bad event"),

326

327 System. cut println ( "unregisterEvents, removing event queue from registry list"),

328 registrvLiεt rerroveElement (eventQueue) , 329

EventManagerlmpl . java_l Mon Nov 11 16:26:42 1996 8

330 if (registryList . isEmptyO ) {

331 System out println ( "unregisterEvents , removing hash table entry for event " + eventName);

₃ 2 eve-itRegistrations remove (eventName) ,

333 }

334 } 335

336 /*

33 * Write t e updatec eventRegistrations table to

338 * perεiεte-t storage

339 */

340 updateEventRegiεtratlons ( ) 341

342 /*

343 * If the queue's list of registered events is empty, remove

344 * the queue's naεr t ole entry

345 */

346 if (notify iεt ()) {

347 System ou . printl ( "unregisterEvents , removing event queue's hash table entry"),

348 eventKot l f icaticrε remove (eventQueue) ;

349 }

350 }

356 * This method is often called by finalizerε, εo it ignores errors

357 */

358 public synchronized VCJC I nregiεterAl 1 (EventPost eventQueue) 359 throws IOE> ceDt-or {

360

361 if ( ullRegiεtrat icns contains (eventQueue) ) {

362 /*

363 * If the event queue was registered to receive all registrations,

364 * remove it from the ful iRegiεtrat ions hash table

365 */

366 Syεtem cut pr tlr ( "unregiεterAll , removing full registration");

367 fullRegι=*-ratιons removeElement (eventQueue) ,

368 369

370 * Write the updated fullRegistrations list to

371 * persistent storage

372 */

373 updateFullRegiεtrationε ( ) ,

374 } else {

375 /*

376 * Locate the queue's list of registered events

EventManagerlmpl. java_l Mon Nov 11 16:26:42 1996 9

377 */

₃ 8 Vector rotifyL st = (Vector ) eventNotifications get (eventQueue) ,

379 if (nctilyList == null)

380 return 381

382 Syste"- out Dπntlnf unregisterAll , removing event registrations' ) ,

383

₃84 for (Enumeration e = notifyLiεt elements (), e hasMoreElements () , ) {

385 String eventName = (String)⁰ nextElement ( )

386 v stern out pr l ~ tin ( ' nregiεterAl 1 , event - + eventName) 387

388 vector registryList = (Vector ) eventRegiεtrations ge (eventName) ;

389 if (registryList == null)

390 continue

391 / "

392 For each event in the list, remove the queue from the

393 * event's list of registered Objectε

394 " If the lιs_ lε empty remove the event s hash table entry

395 '/

396 System out prntln ( "removing event queue from registry list")

397 registryList removeElement (eventQueue)

398 if (registryList isEmptyO) { 399 Syεtem out println ( ' unregisterAll, removing hash table entry for event " + eventName),

400 eventRegiStrations remove (eventName)

401 registryList = null, 402

403 >

404

405 /*

406 * V te the uodated eventRegiStrations table to

407 * poisiεtent storage

408 */

411 /*

412 * Re~cve the event queue ε haεn table entry

413 */

414 Syster out println ( "unregisterAll, removing event queue'ε hash table entry"),

415 eventϊ_*ct.ιfications remove (eventQueue) ,

416 }

417 }

418

419

420 // Methods tc post events and send notifications

421

422 /**

423 * Notify ob__ctε tnat an event occurred (EventPost interface)

EventManagerlmpl. java_l Mon Nov 11 16:26:4₂ 1996 10

424 * ©param event Event eing posted.

425 * ©exception EventException If an error occurs posting the event.

426 */

427 public synchronized void postEvent (EventType event)

428 throws ReϊoteException, EventException, IOException {

429

430 System out println ( "EventManager , posting event"),

431 /*

432 * Handle specific registrations for this event Locate this event'?

433 * entry m the eventRegiStrations hash table and post the event to

434 * each ot the event queues on .ts hash chain

435 */

436 String eventName = event getClass (). getName () ;

437 System out println ( "postEvent , event = " + eventName) , 438

439 Syεtem out p intln ( "o: εtEvent , checking specific registrations.");

440

441 /*

442 * Post tr.- event to t-3 event queues registered to

443 * receive it

444 */

445 Vector b dEventRegiε ra lonε = new Vector!) , 446

447 Vector regiεtryList = (Vector ) eventRegiStrations get (eventName) ;

448 if (regiεtryLiεt '= null) {

449 Syεtet out .println (" registryList contains " + registryList . εize ( ) +

450 ' elements"! 451

452 ' - (Enumeration e = registryList ele^ments (), e . hasMoreEle entε ( ) , ) {

453 EventPost eventQueue = (EventPcεt)e nextElemen ( > , 454

455 System tut pr tln ( "Pcst g event' .,

456

457 try {

458 eve-t jeue poεtEv?rt(eve"tl ,

459 ; catch (Exception e2) {

460 System out .prmtln ( "Event post failed");

461 badF --- tRegistrations addElement (eventQueue) ;

462 >

463 }

464 }

465

466 /*

467 * Post the event to all Objects that have requested notification

468 * of. ll events

469 */

470 SysteT out print In ( 'postEvent , checking full registrations").

_EventManagerlmpl . ava_l Mon Nov 11 16 : 26 : 42 1996 11

4 1 System out print l i ( ' fu l lRegistrations contains " + ful lRegistrations size d +

472 " elements" )

473 4-74 Vector oadFullRegiεtrations = new Vector () 4-75 for (Frumerat.cn e = fullRegistrations elements (), e hasMoreElements () , ) { 4-75 EventPost eventQueue = (EventPost) e nextElement ( )

4/7

₄ 8 Syεtem out prir -In ( 'Posting event')

479 try <

480 eventQueue postEvent (event )

481 ) catrn (Exception e3 ) {

482 System cut println ( "Event post failed'),

483 badFullRegiεtrations addElement (eventQueue) ,

484 }

485 } 486

487 /*

488 * If the EventManager was unable to contact any event queues,

489 * remove them from eventRegiStrations and/or fullRegistrations

490 * and update the a^~fected reσiεtrationε in perεiεtent εtorage

491 */ ^"

492 if ( ' badEventRegistre -ions isEmptyO) {

493 for (Enumeration e = badEventRegiεtrationε elements)), e hasMoreElements ( ) ) {

494 EventPost eventQueue = (EventPoεt)e nextElement ( )

495 Syεtem out pr tln ( "Removing bad event queue from registry list"),

496 registryList removeElement (eventQueue) ,

497 }

498 updateEv«P ι. = g. s^f i-≤tions O

499 )

500 badEλ =ntF r.st = '- ι r— _s - null 501

502 if ( l±F°ι is"ra- 1 ~ c- icEmotyO) {

503 for Enuπeratic- e = badPullRigiεtra t ions elements)), e hasMoreElements ( ) ) {

504 EventPcεt eventQueue = (EventPost)e ne> tElement ( )

505 Syεtem cut pr tln (' Removing bac event αueue from full list'),

506 f l eoi = trationε rerroveElem=τ t (e\ entQueue) 507

508 upda-εFu_iRegι=t-atιons ( )

509 }

510 badFullRegiεtrations = null, 511

512 } 513

514

515 // Methods to handle persistence

516

517 /**

EventManagerlmpl. java_l Mon No\ 11 16:26:42 1996 12

518 * Allocate a persistent store manager and restore

519 * eventRegiStrations ana fullRegistrations (If they

520 * don't exist in the persistent store, instantiate

521 * new ones.) Tnen reconstruct eventNotif ications from

522 * eventRegiStrations

525

526 Boolean erab.ed = new Eoolean (qetProper tv (ENΛBLE_PERSISTENCE, false )),

527 if ('enables booleanValue ( ) ) {

528 /*

529 * If persistence is disabled perform initialization,

530 * but net rec-very

531

532 System cut crirtli ( recoverRegistrations persistence disabled )

533 persiεtentStoreFile = ' ",

534 persiεtenceManager = null

535 eventRegiStrations = nee Hashtable ()

536 fullReciεtrations = new \ector(),

537 eventKc t i f icat lens = new Faεhtable()

538 return

539 540

541 Syεtem o_t prmtln ( Persistence enabled ' )

542 persistentStoreFlle = getProperty (PERSISTENCE_FILE, " ),

543 System out pri- tin (' EventManager persistence FileName property set to " persistentStoreF 544

545 /*

546 * If no file is specified use the default

547 *

548 if length)) == 0)

549 persistentStoreFlle = AgentConstants AGENT_DIR + DEFAULT_PERSIΞTENCE_FILE

550 System out o__nι_m( Perε.εtert Store File + perεiεtentStoreFile) 551

552 persistence m? ' - n= rκ=rειstentStoreHandler (pei «- istentStoi eFile) 553

554 /*

555 * Fetch registrations from the persistent store If they don't exist,

556 * instantiate e/ertRogistrations and fullRegistrations

557 */

558 System out prmtln ( eventRegiStrations )

559 if ( (eventRegiStrati

560 (Hashtable) perεistenceManager fetchObject (EVENT_REGISTRATION_ID) ) == null)

561 eventRegiStrations = new Hashtable () ,

562

563 System out println) Fetching fullRegistrations')

564 if ((fullRegistrations =

EventManagerlmpl. java_l Mon Nov 11 16:26:42 1996 13

565 (Vector)persιstenceManager fetchObject (FULL_REGISTRATION_ID) ) == null)

566 fullReg.straticns = new Vector!) 567

568 /*

569 * Reconstruct the e e-¹: no ifications using event registrations Then

_D70 * truncate t e oers,: ^nt store and write out the registrations

571 */

572 Syεtem out r..rtln ( ' 'e-onrtr.rtim ev n notifications')

573 reconstruct' oti fir? t ions ( ) 574

575 System out println (' Sa ing registrations')

576 saveRegistrations ( )

577 }

579

580 /**

581 * Truncate persistent storage and ur.te out event and full

582 * regiεtraticr s

583 */

584 protected void saveRegistrations ( ) {

585 if (persiεtence anaσe" == null)

586 return

587

588 perεistenceManager truncateFileStore ( )

589 persistenceManager msertOb] ect (E,/ΞNT_REGISTRATION_ID,

590 eventRegiStrations STORAGE_PADDING) ,

591 persistenceManager insertObject

592 fullReσ_stratιcnε STORAGE_PADDING)

593 } 594

595

596 /**

597 * Update eveⁿ^ reqiεtr? t ions m persistent storage

598 */

599 protected void updateEventRegiεtrations ( ) {

600 if (persistenceManager == null)

601 retur-

602

603 System out prmtln (' Updating eventRegiStrations")

604 persistenceManager updateObject (EVENT_REGISTRATION_ID, eventRegiStrations),

605 }

606

607 608

609 * Update full registratioⁿs in persistent storage

610 */

611 protected void uιodateFu l lR-=g ιs trat i ons ( ) {

EventManagerlmpl . ava_l Mon No 11 16 : 26 : 42 1996 14

612 if (persisterce anage; == null)

613 return

614

615 System out pr_πtln( Updating fullRegistrations'),

616 persistenceManager updateObject (FULL_REGISTRATION_ID, fullRegistrations),

617 ) 618 619

620 /**

621 * Reconstruct the event noti ica ion^ table from tb«

622 * event regie traticnε table

623 */

624 protected vo d leconstruct otif ications ( ) {

625 eventNotif icatiopε = new Hashtable)), 626

627 if (persistenceManager == null)

628 retuπ 629

630 /*

631 * Reconεtruct the eventNotif ications haεh table βy walking

632 * the EventRegis-rat.onε haεh table and extracting registrations

633 */

634 for cEnumeration registryKeyε = eventRegiStrations keys ( ) ,

635 regiεtryKeyε nasMoreElements ( ) ) { 636

637 /

638 * For each k°j, (event name! in the table obtain the list of

639 * regiεtered evert σueue^ 540 ^*/

641 String eventName = (String) registryXeyε nextElement ( )

542 Syεtem out on n^~l^r- (' reconεtructNotifications , event = " + eventName),

-43 Vector recistryL εt = (Vector ) ventRegiStrations get (eventName)

544

645 /*

546 * If no objects have regiεtered to receive this event

547 * re-cve it from the eventRegiStrations hash table

648 */

649 if ( (.registryList == null) | | (registryList lsEmoty)))) {

650 Syεtem out crintlnf reconεtructNotif ications , removing haεh table entry for event ' + event 551 eventRegiStrations remove (eventName) ,

652 cont inue

653 }

554

555 / '

_>56 * Add the event name to the eventNotif ications entry of

557 * each of the registered event queues, creatmq ha=-h table

558 * entries as necessary

EventManagerlmpl. java_l Mon Kov 11 16:26:42 1996 15

559 */

560 for (Enumeration regiεtryElements = registryList elements)),

561 reg-str Fleme^tε hasMoreElements ( ) ) {

664 Vector notιf_n.ιst = (Vector ) ever tNot if ic? t: onε get (eventQueue) ,

665 if (rotifyList == null) {

666 not fyLiεt = new Vector ( )

667 eventNotif ications put (eventQueue , notifyList),

668 System o_t onntln( reconεtructNoti icat lonε , created eventNotif ications haεh table ent

669 }

670 notifyLiεt addElement (eventName)

671 }

672 } 573 }

674

575 // Miεc metho ε

576 /** Returns th= EventMaⁿager ε name */

577 protected εtat'c String cetEventManagerName ( ) {

678 return EVENI _ιAN<\GEP„NAS

679 } 580 681

682 /** Returns the value cf a oroperty */ 583 protected String getProperty (String key, String det) {

684 ret.-i properties getProperty (key def)

685 } 586

687 // Mam methoo

588 /**

589 * EventManagerlmpl Dcctε-rarj Thiε is the only way to start

590 * the EventManaαβπ. Sι"ce it haε no public constructors

591 */

592 public εtat-c void mainiStnng args [ ] ) {

593 System setSe -_r_ tyManager (nev. Insecurity Manager ()) , 594 try {

595 EventFanagerlmtj e^ntManager = nevi EventManager Imol ( )

596 } catch (Exception e; {

597 System out omtln("An exception occurred setting up the EventManager ' + 698 e getMessage))),

599 e printStackTrace () 700

701 )

702

703 }

704

705

EventManagerProxy. java_l Mon Noir 11 16:26:42 1996 1

1 /* $Header: /co-./meitca/hsl/ zonesjagents/event/EventManagerProxy . Java 1 10/22/96 7:30p Noemi $ 2

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center America

5 * All rights reserved 6

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA 8

9 * DESCRIPTION

10 * A client proxy fcr tne Fvc itManager

11

12 * SLog • /com/meitca/hsl/ zcneε₃agentε/event /EventManagerProxy ₃ava $

13

14 * 1 10/22/96 " 3Cp Noemi

15 * EventManagerProxy lε tne puclic interface to the EventManager It

16 * εhields users from the effects of EventManager crashes

17 */ 18

19 package com.meitca hεl zcnes₃= entε event, 20

23 import ₃ava rmi RemoteException,

24 import nava.rmi Naming,

25 import Java rmi Remote;

26 ^'

27

28 /**

29 * EventManagerProxy is the ouclic interface to the EventManager As a

30 * proxy for the Event *>'anac r, it maintains a reference to the actual

31 * Event Manager and sh eldε users from the effects of Event Manager

32 * crashes. Whenever the proxy fails to communicate with the Event Manager

33 * it attempts to re-establish a connection to it 34

35 * @see EventManager

36 * @see EventManagerIrol

37 * Sauthor Noemi Pactcrek

38 */

39

40 public class EventManagerProxy {

⁴ 42¹ // Constants

43 protected static final int DEFAULT_RETRIEΞ = 2;

44 protected static final long DEFAULT TIMEOUT = 10000,

45

46

47 // Instance varia^bles

EventManagerProxy. java_l Mon Nov 11 16:26:42 1996 2

48 /** Stub for EventManagerlmpl ' s EventManager interface */

49 protected EventManager eveitManager

50

51 /** Stub for EventManagerI ppl ' s EventPost interface */

52 protected EventPost eventPost

53

54 / * * The Even ^ma gerlmpl s name * /

55 protected St _ g even tManac erName 56

57 /**

58 * The number cf times to retry when an invocation

59 * on the EventManager fails

60 */

61 mt retrieε 62

63 /** The timeout per_oα n -s for requests to the EventManager */

64 long timeout 65

66

67 // Constructors

68 /**

69 * Construct'' ~n TventMa^acerProxy

70 */

71 public EventMaragerProxv ( )

72 throws Eiceotion { 73

74 this (DEFAULT RET^IFS EE~AULT_TIMEOUT)

75 } 76

77

78 I * *

79 * Constructs an EventManaσerProxv

80 * Sparam retries The nαtoer of timeε to retry if an operation fails

81 */

82 public EventKanacerProxy ( I"- 1 retries)

83 thro s E> section { 84

85 this (retries DEFAULT TIMEOUT)

37 88

89 /**

90 * Constructs an EventManagerProxy

91 * @param timeout The time to wait in ms between retries

92 */

93 public EventMaragerProxy ( long timeout)

94 throws Exception {

EventManagerProxy . j ava_l Mon Lvlov 11 16 : 26 : 42 1996

95

96 this (DEFAULT_RETRIES timeout),

97 } 98

99 100 /**

101 * Constructs, an EventManagerProxy

102 * @param retries The n^oer of times to retry if an operation fails

103 * @param t_meout The t-re to wait in mε between retries

104 */

105 public EventManagerProxy ( j-t retries long timeout)

106 throws Exception { 107

108 this retr.es = (retries >= 0) ^■> retries DEFAULT_RETRIES

109 this timeo.t = (timeout > 0 ) ' timeout DEFAULT_TIMEOUT 110

111 /*

112 * Lookup the EventManager

113 */ ^"

114 initialize))

115 } 116 117

118 // Instance r ethcds

119 /*

120 * Lookup the Event Manager in the RMI registry and obtain a

121 * stub for _t= E entManager and EventPost interfaces

122 */

123 private void _mtιalιze ( )

124 throws Exception { 125

125 eventManagerNarre = Even-Manaaerlm.pl getEventMa^agerName ( *

127 try {

128 Remote εtuo = λamng lookup (eventManagerName)

129 eventManaσer = (EventManager ) εtub

130 eventPost = (EventPost ) εtub

131 } catch 'Exception e) {

132 Syεta- out prmtln (' initialize error looking up EventManager

133 - e getMessage ()) ,

134 e printStackTrace ( )

135 throw e,

136 }

137 }

138

"39

140 /*

141 * Block for the timeout i-terval Then look up the

EventManagerProxy. j ava_l Mon Nov 11 16:26:42 1996

142 * EventManaσ=r

143 */ 144 private void waitAndlnitialize ( ) 145 throws Exception { 146 147 synchron-zed ( this ) { 148 try { 149 this wait i timeout) , 150 } catch ( InterruptedException e) { } 151 } 152 initialize I ) . 153 } 154 155 /* 155 * Convert the evert class names to strings 157 */ 158 private Strin r] eventKametoStπng (Event ype [ ] eventε) { 159 160 int length = events length, 161 String evertrameεP = new String [ length ] 162 for (int 1 = 0, ι -v. _^ength, ι++) { 163 eventKaiτts [ l] = events[ι] getClassO getName ( ) 164 System out print In (" eventNametoStr mg , event = -^J- eventNameε [ l ] ) 165 } 166 return e\ er Nameε 167 158 169 170 171 // Methodε to nardle rec iεtratmns 172 173 174 * Register _ιterεst receiving εoecified eventε 175 * Sparam events An array of eventε an obnect lε _nterested in receiving 176 * Sparam t -/entQueue The associated event queue's EvertPost interface 177 * RemoteException If an error cccurrs sett_ng up network 178 * connectionε 179 * Sexception lOExceotien If the tranport layer generates one 180 */ 181 public void registerEverts (EventType events [] , EventPost eventQueue) 182 throws Exception { 183 184 r 185 * Convert the event class names to strings 186 * Then invoke the EventManager ' s registerEvents 187 * method and retry the operation, if necessary 188 */

EventManagerProxy. java_l Mon Nov 11 16:26:42 1996 5

189 String eventNames L ] = eventNametoStnng (events)

190 for (int _^ = 0 i <= retries ι++) {

191 try <

192 eventManager registerEvents (eventNames eventQueue)

193 return

194 ] catch (^RemoteException el) {

195 if (i =" ret jes) {

196 System cu- prmtln (' registerEvents Throwing RemoteException'),

197 throw el

198 )

199 Sytem out prmtln (' registerEvents Caught RemoteException')

200 ; catch (IOExceotion e2) {

201 if d == retries) {

202 ^cystem cut prmtln (' registerEventε Throwing IOException')

203 ι hrow e2

204 }

205 S =ten out t_ rtln( registerEvents Cauαht IOException' )

206 }

207 /*

208 * Block ιθr t^1-- timeout interval Then look up the

209 * EventManager before retrying the operation

210 */

211 waιtA^cInιtιa_ιz=: ( )

212 }

213 ) 214

215

216 /**

217 * Register interest m receiving all eventε posted to this EventManager

218 * Θparam ev-τtQueje Tne associated event queue ε EventPoεt interface

219 * ©exception RemoteException If an error occurrs setting up network

220 * connections

221 * ©exception IOExceot_on If the tranport layer generates one

222 */

223 public void reαiεte All I Ex ent^Doεt eventQueue)

224 throws Excecticn { 225

226 /*

227 * Invoke tne EventManager ' ε regiεterAll

228 * method ard retry the operation, if necessary

229 */

230 for (int _ = 0 l <= retries ι++) {

231 try {

232 ev/entManager regis terAl l ( eventQueue )

233 return

234 } catch (RemoteException el) {

235 if (l == retries) {

EventManagerProxy. java_l Mon 'Jov 11 16:26:42 1996 6

236 System out prmtln (" registerAll Throwing RemoteException"),

237 t ire,) el

238 }

239 Syεte.n out prmtln ( ' egisterAl l Caught RemoteException ' ) ,

243 throw e2

244 }

245 System out p_ i ntln ( ' rpqi ε terAl 1 Cauqht IOException")

246 }

247 /*

248 * Block for the timeout interval Then look up the

249 * EventManager, before retrying the operation

250 */

251 waitAndli i ialize ( )

252 }

253 } 254

255

256 // Methods to jn-egister events

257 /**

258 * Remove registration for specified eventε

259 * Sparam eventε An array of eventε an ob₃ect is interested in receiving

260 * Sparam ev=ntQueue Tne aεεociated event queue's EventPoεt interface

261 * Sexception emo'-eΞxctptιon If an error occurrε setting up network

262 * connections

253 * Sexception Ev>nt aracerEyceptιon If the erent σueue was not registered

264 * for one or mere of the SDecified exceptioⁿs

265 * Sexception ^"O^rλc°ptιcn If the tranport layer generates one 256 */

267 public void unregisterEvents (EventType events[], EventPoεt eventQueue)

268 throws Excεc^r.on { 269

270 /*

271 * Convert the event clasε nameε to strings

272 * Then ιnvok^a tne EventManager ' s registerEventε

273 * method a-α retry the operation, if necessary

274 */ ^'

275 String eventNames [] = eventNametoStrmg (events )

276 for (int l = 0 i <= retries, ι++) {

277 try {

278 eventManager unregisterEvents (eventNames , eventQueue) ,

279 return,

280 } catch (RemoteException el) {

281 if (- == ret-mε) {

282 System out print In (' unregisterEvents Throwing RemoteException')

EventManagerProxy. ava_l Mon Nov 11 16:26:42 1996 7

283 throw el

284 "

285 Syεtem out prmtln (' unregi sterEvents Caught RemoteException")

286 } catch (IOException e2) {

287 -f (i == retries) {

288 Syεtem out println) unregisterEvents Throwing IOException' ) 289 throw e2

290 '

291 Syεtem out prmtln ( unregiεterE/entε Caught IOException' )

292 }

293 /*

294 * BICC for the timeout interval Then look up the

295 * E\ ertf'anager , before retrying the operation

296 */

297 waitAnd- itialize ( ) ,

298 }

299 }

300 301 302 /

303 * Remove registration f^r all eventε

304 * θparam evie-itQue The aεεociated event αueue'ε EventPoεt interface

305 * This method is often called by finalizers so it does not

306 * propagate a-ⁱy errorε

307 */

308 public void u-'egis terAl 1 (EιΛent^Doεt e' (

309 /*

310 * Invoke tne Ev=rt'""anaαer s registerAll

311 * method a^o retry the operation if neceεεary

312 */

313 for ( t _ = D l <= retrieε ι ++) {

314 trv i

315 eventManager unregiεterAll (eventQueue)

317 } catch (RemoteException el) {

318 Syεtem out prmtln ( "unregisterAll Caught RemoteException' ) ,

319 } catch (IOException e2) {

320 System out prmtln ( "unregisterAll Caught IOException' ) ,

321 }

322 /*

323 * B-Ock for the timeout interval Then look up the

324 * EventManager, before retrying the operation

325 */

526 try {

327 waitAndlmtializeO ,

328 } eaten (Exception e3 ) {

329 System out println (' waitAndlnitialize failed )

EventManagerProxy. java_l Mon Nov 11 16:26:42 1996

330 }

331 }

332 }

333

334

335 // Methods to post e/ents

335

337 /**

338 * Event notification interface

339 * θparam event The event to post

340 * Sexception RemoteExceotion If an error occurrε setting up network

341 * connections

342 * Sexception EventException If an error occurs posting the event

343 * Sexception If the tranport layer generates one

344 */

345 public void postEvent (L a" tType event) 345 throws E>ceotj.on {

347 /*

348 * Invoke the EventManager ' s eventPost 3 -a 9 * methc 1 and retry the operation if necessary

350 */

351 for (int _ = 0 i <-= retries ι^+) {

352 try <

353 eventPoεt postEvent (event )

354 retu_n

355 } catch (RemoteException el) {

356 f (l == retries) {

357 System c_t orintlrl ostEvent Throwing RemoteExceotion')

359 ^

360 System out println ( oostΞ,ent Caught Remo^teException )

361 } catch (^τOΞxceotιm e2)

362 f (l == ret.mε) {

363 Syεtem c_t orintlnl postEvent throw c lOExceot ion' )

365 }

366 Syεtem out prmtln ( postEvent Caught lOExceotion' ) 367 }

368 /*

369 * Block for the timeout interval Then look up the

370 * Eλ'entMdnager before retrying the operation

371 */

372 waitnrdlritialize ( )

373 }

374 )

375 } 376

> o z a o s

o μ o> S

S u c

> w EventPost. java_l Mon Nov l 16:26:42 1996 1

1 /* SHeader /com/meitca/hsi zcneεnagentε/event/EventPoεt ₃ava 2 10/22/96 7 lOp Noemi $

2 *

3 * Copyright 1996 Horizon Systems Laboratory Mitsubishi Electric

4 * Information Technology' Cen^ter America

5 * All rights res_crveα 6

7 * CONFIDENTIAL AND PROPR^'ET^Y PROPERTY OF MITSUBISHI ELECTRIC ITA

8

9 * DESCRIPTION 10 * Interface for event notui ation 11

12 * $Log /com/me_tca hsl /zcnes agentε/event/EventPoεt ]ava $ 13

14 * 2 10/22/96 ⁿ Op Noemi

15 * Changed the th^c v clause of the postEvent method 15

17 * 1 10/14/96 6 5^p Noemi

18 * Interface used f^ c st o = cents

19 */

23 import nava io *

24

25 import ₃ava rmi Remote

26 import nava rmi Re' -t^Ex-ep i ~ ~ 27

28 /**

29 * EventPost lε a _ st^but- ^"UJI interface for notification of eventε 30

31 * Sauthor Noemi "eci-re

32 */ 33

34 public interface '-i-'Piit

35 extends Remote 36

37 // Instance methods

38 /**

39 * Event notificat oi interface 40 * Spara eve^rt The event to poεt

41 * Sexception RemoteΞxceo" ion If an error occurrs setting up network

42 * connections

43 * Sexceotion E^entExceotion If an error occurs poεting the event

44 */

45 public void poεtEvent (EventType event)

46 throws Remote^Exception EventException IOException 47

WO 98/21662 - 2 £^~ - PCT/US97/20232

> o '_. c o

E

EventQueuelmpl. java_l Mon Nov 11 16:26:42 1996 1

1 /* $Header /com/me tca/hsl /zonesnagentε/event/EventQueuelmpl ava 1 10/14/96 6 58p Noemi $

2 *

3 * Copyright 1996 horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL AND

8

9 * DESCRIPTION

1 0 * Event queue d i ε t l u ted bτ ~

11

12 * SLog /com/meιtca/h=l/zores lagents/event/EventQueuel pl ₃ava $

13

14 * 1 10/14/96 6 58p Noemi

15 * Event queue implementation

16 */ 17

18 package com meitca hε_ zcneε-iagentε event 19

20 import nava uti] ^*

21

22 import ₃ava rmi server Uncast^;-ιnteServer

23 import ]ava rmi

24 import java rmi

25 import ]ava rmi NotSoundExcep ion

26

27 /**

28 * EventQueuelrmol is ?n event iieue that implemen ^ the FMI

29 * EventPoεt mter_ = ce

30 *

31 * Event notification lε performed by appending an event to the queue

32 * Each queue has an associated EventQueueThread started by the constructor

33 * The thread dequeu s everts ai calls their handlers 34

35 * θsee EventQueueThread

36 * Ssee EventPost

37 * Sauthor Noemi ^c cιorek

38 * /

39

40 publ ic class EventQueuelmpl

41 extends UmcastRemoteServer

42 implements EventPos^1- {

43

44 // Instance variables

45 /** The event σueue */

46 protected Vectci eventQueue 47

EventQuauelmpl. java_l Mon Nov 11 16:26:42 1996 2

48 /** The thread that manages this queue */

49 protected EventQueueThread queueThread; 50

51 // Constructors

52 /**

53 * Protected De f au l t Cons tru ' tor f or EventQueuelmpl

54 * ©exception IllegalAccessException Wn^never called

55 */

56 protected EventQueuelmpl ( )

57 throws RemoteException, IllegalAccessException { 58

59 Syεtem out prmtln ( "De ult constructor called for EventQueuelmpl"),

60 throw new IllegalAcceεsException ( "EventQueuelmpl default constructor"); 51 }

52

63 /**

64 * Constructs an EventQueuelmpl

65 * βparam hardier An EventHandler interface

66 */

67 public EventQueuelmpl (EventHandler handler)

68 throws RemoteException _v

69 eventQueue = new Vector ();

70 queueThread = new EventQueueThread ( this , handler),

71 )

72

73 /**

74 * Constructs an EventQueuelmpl

75 * θparam handler An Ξve-tHandler interface ^π β * θparam timeout The tint m ms to wait between consecutive queue

77 * examinations

78 */

79 public EventQueuelmpl (EventHandler handler, long timeout)

80 throws RemoteExceptio*-

81 eventQueue = new Vector!) ;

82 queueThread = new EventQueueThread ( this , handler, timeout),

83 } 84

85 // Instance methods

86 /**

87 * Posts an event by enqueueing it and waking up the

88 * queue's thread

89 * Sparam event The event to post

90 */

91 public synchronized void postEvent (EventType event) {

92 System, out .pr tln ( "EventQueuelmpl, posting event");

9 933 eennqquueeuuee ((eevveenntt )) ;;

94 this notify, 11 ()

EventQueuelmpl. java_l Mon Nov 11 16:26:42 1996

95 }

96

97 /**

98 * Enqueues an event 99 * Sparam event The eve t to σueue

ICO */ ^'

101 protected final εynchromzeα void enqueue (EventType event) {

102 eventQueue addElemen (event )

103 } 104

105 /**

106 * Dequeues an evert

107 * θreturn The first eve-, in the queue

108 */

109 protected final εynchronized EventType dequeue ( )

110 throws ArraylndexOutOfBι undsException { 111

112 if ('eventQueue lεEmpty _v ) ) {

113 EventType event = (EventType) (eventQueue f lrεtElement ( ) ) ,

114 eventQueue removeElementAt ( 0 )

115 return event,

116 }

120 121 122 123 124 125 126 127

EventQueueThread. java_l Mon Nov il 16:26:42 1996 1

1 /* $Header: /com/meitca/hsl/zonesjagentε/event/EventQueueThrea . java 1 10/14/96 6-59p Noemi $

² *

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center America

5 * All rights reserved * CONFIDENTIAL AND PROPRIETAR^Y PROPERTY OP MITSUBISHI ELECTRIC ITA

' , * ζ * DESCRIPTION

10 * Thread that manages an event queue 11

12 * $Log /co /meitca/hsl/zoneεjagentε/event/EventQueueThread ava $ 13

14 * 1 10/14/96 6 59p Noemi

15 * Thread to manage the event α =u e

16 */ 17

18 package com meitca hs_ zoneεjagentε event, 19

20 /**

21 * EventQueueThread lε a Thread that manages an event queue

22 * Event notification is implemented by appending an event to the queue

23 * and waking up its EventQueueThread to process the event by calling its

24 * event handler.

25 * The EventQueueThread lε instantiated by the EventQueuelmpl constructor

26 *

27 * θεee EventQueuelmpl

28 * θsee EventPost

29 * θsee EventHandler

₃0 * θauthor Noemi Pacore

31 */

32 class EventQueueThread

33 extends Thread ' 34

35 // Constants

36 /** The default timeout value in ms */

37 public static firal long DΞF2>ULT_TIMEOUT = 1000, 38

39 // Instance variables

40 /** This thread's event queue */

41 protected EventQueuelmpl eventQueue;

42

43 /** The application's event handler */

44 protected EventHandler evencHandler ;

45

46 /** The time ι- ms between consecutive examinations of the queue. */

47 protected long timeout,

EventQueueThread. java_l Mon Nov -.1 16:26:42 1996

48

49 // Constructors

50 /**

51 * Protected Default Constructor for an EventQueueThread

52 * SexceDtion IllegalAccessException Whenever called

53 */

54 protected EventQueueThread)

55 throws Illega¹ { 56

57 System out cnntln( Default constructor called for EventQueueThread' ) ,

58 throw new I HegalAccessException ( "EventQueueThread default constructor"),

59 } 60

61 /** Constructs an EventQueueThread

62 * Sparam queue The associated event queue

63 * Sparam handler The associated event handler interface

64 */

65 public EventQueueThread (EventQueuelmpl queue, EventHandler handler) { 65 this (queue, han ler DE" ULT_TIMEOUT) 67 } 68

69 /** Constructs an EventQue-eThread

70 * θparam σueue The associated event queue

71 * θparam hardier The aεεociated event handler interface

72 * θparam timecut The time in mε to wait between consecutive σueue

74 */

75 public EventQue leThreed ( ⁱ = tQueuiImt l αueue, EventHandler handler long timeout) {

76 eventQueue = queue

77 eventHandi-i = handler

78 thiε timeout = tιmeo_t

79 thiε start')

80 } 81

82 // Instance met'odε 83 84 /**

85 * The thread ε run method

86 */

87 public void ru^ {

88 while (true {

89 try {

90 ε nchronized (eventQueue)

91 eventQueue wait ( timeout) ,

92 } 93 } catch (InterruptedException e) { }

94

EventQueueThread. java_l Mon Nov 11 16:26:42 1996 3

95 EventTy e event,

96 while i (event = eventQueue dequeue () ) '= null) {

97 Syεtem out prin 3 n (' EventQueueThread, handling event"),

98 try {

99 eventHandler handleΞvent (event) ,

100 } catch (Exception ex) {

101 System out println ( EventQueueThread can't handle event " +

102 ex getMessage ()) ,

103 ex printStackTrace () , 104

105 }

106 }

107 }

108 } 109 110 111 112 113

1 14

EventType . j ava_l Mon Nov 11 16:26:43 1996 1

1 /* $Header- /com/meitca/hsl/zones jagents/event/EventType ]ava 1 10/14/95 6-55p Noemi $ 2

7 * CONFIDENTIAL AND PROPRIETARY PROPERTY OF MITSUBISHI ELECTRIC ITA

9 * DESCRIPTION 10 * Base class lor distributed even s 11

12 * $Log /co /me-tca/hsl ' zoneε₃agentε/event/EventType ₃ava $ 13

14 * 1 10/14/96 6:55p Noemi

15 * Base class for distributed events IS */ 17

18 package com meitca hsl zonesjagents event, 19

20 import com meitca hsl util UniquelD; 21

22 /**

23 * Base claεε for diεtributed eventε EventType describes an event

24 * It contains- a unique ID (generated by the EventManager) and a description

25 * (optionally paεεed to the constructors)

26 *

27 * Aoplicationε ~^,uεt derive and nandle tneir cw evert types 28

29 * Sauthor Noemi Pacicrek

30 */ 31

32 abs tract publ i c c laεε Eι/en tTyp» 33

34 // Constants

35 private static final String UNKNOWN = "Unknown",

36 private static final Strmσ TYPE = "event", 37

38 // Instance variables

39 /** A unique ID representing the event */

40 protected String eventID,

41

42 /** A description of the event */

43 protected Ξtrirg description,

44

45

46 // Constructors

47 /** Constructs an EventType */

EventType. java_l Mon Nov 11 16:26:43 1996 2

48 public EventType () {

49 this 'UNKNOWN) ,

50 }

⁵¹

52 /** Constructs an EventType

53 * Spara descriotion String describing the event

54 */

55 public Evenf^~vpe(S πrc ι°^ccπptιon) { i.6 eventID = UmquelD q-tMextID (TYPE, this) ,

5 System out pr tln ( 'eventID = ' + eventID)

58 this description = description

59 } 60

61

62 // Instance methods

63 /**

64 * Stπrg representation of event

65 * θreturn a String representation of the event

66 */

67 public f_nal String toStringO {

68 return (eventID ^■*^■ + description)

69 ) ^0

71 /**

72 * Retrieve an event ε ID

73 * Sreturn Tie e s ID

74 */

75 public fιna_. Strmσ getEven- "D ( ) {

76 return eventID

77 } 78

79 /**

80 * Retrieve an event's dsscription

81 * θreturn ? oesc-'ctici - tne event

82 */

83 public final String getE^e-tleεcr lption ( ) {

84 return descimtion

85 }

86 87

89 90 91

92 93 94

> o z ti o

Mon Nov 11 16:23:18 1996 1

1 /* $Header /com/meitca/hsl/zones agents/shared/PersistentStoreHandler ₃ava 1 10/22/96 7 32p Noemi $

2 *

3 * Copyright 1996 Horizon Systems Laboratory, Mitsubishi Electric

4 * Information Technology Center America

5 * All rights reserved

6 *

7 * CONFIDENTIAL AND PROPRIETARY PROPEPTY OF MITSUBISHI FLFCTRIC ITA 8

9 * DESCRIPTION 10 * Persistent Store Manager wrapper that handles exceptions 11

12 * $Log /com/meitca/hsl/zonesjagentε/shared/PersistentStoreHandler java $ 13

14 * 1 10/22/96 7 32p Noemi

15 * A generic wrapper for PersistentStoreManager that catches exceptions

16 * and retries operations as necessary

17 */ 18

19 package com meitca hsl zonesjagents shared

20

21 import com meitca hs_ zonesjaσentε persistence * 22

23 /**

24 * A wrapper claεε tor the persistent storage manager

25 * (persistence PersistentStoreManager ) that catches

26 * all its exceDtionε ana performs the appropriate cleanup

27 * θsee PersistentStoreManager

28 * Sauthor Noemi Paciorek

29 */

30 public class "ersiscentStoreHandler { 31

32 // Inεtance variables

33 /** A reference to tne persistent store manager */

3 pi-c tected "erii"- mtΞtιr=Manaoer persistenceManager 35

36 // Constructorε

37 /**

38 * Constructs a Persistent StoreHandler

39 * θparam filename The name of the persistent storage file

40 */

41 public PerεiεtentStoreHandi =r (Str i ng filename) {

42 try {

43 persistenceManager = new PersistentStoreManager ( filename)

44 } catch (PersistentStoreException e) {

45 System out println ( "PerεiεtentStoreHandler can t create persiεtent store manager ' + e getMeε

46 e printStackTrace () ,

47 pers.sterceManacer = null

Mon Nov 11 16 : 23 : L8 1996 2

48 }

49 } 50

51 // Finalizer

52 /**

53 * Deletes refeience to Per_εtentStoreManager

54 */

55 protected void fmalιze(,

56 throws Throe < θle { 57

58 System out or mtln ( " PerεiεtsntStoreHandler Finalizer called"),

59

60 // Delete reference to Persistent Store Manager

61 persistenceManager = n_.-.i 62

63 super final. e()

64 } 65

66

67

68 // Instance methods

69 /**

70 * Find an object in the persist εtore

71 * Spara object The Object to locate

72 * Sreturn The Object s persistent storage ID

73 */

74 public int findObject (Object object) {

75 return pers.stenceManagsr findObject (object )

76 } 77

78 /**

79 * Inεert an Object into persistent εtorage

80 * If a εtorage manager exception occurs, attempt to

81 * truncate the persistent εtorage and disable persistence

82 * θparam object The Object represented by id

83 * Sreturn The Object s persistent storage ID

84 * A return val le of PersistentStoreManager INVALID_OID indicates

85 * an unsuccesstul attempt tc insert the object

86 */

87 public mt insertObject (Object object) {

88 return insertObject ( 0 , object, 0),

89 } 90 91

92 / * *

93 * Inεert ar Obj ect into pers i stent storage

94 * I f a ε torαgr r inagei » ~ ->pr ι on oc ii i '- , <ι t t on,pt I n

Mon Nov 11 16:23:18 1996 3

95 * truncate the persistent storage and disable persistence

99 * θreturn The Object s persistent εtorage ID

100 * A return value of PersistentStoreManager INVALID_OID indicates

101 * an unsuccessful attemot o nεert the object

102 */

103 public int insertObject (Object object, mt space) {

104 return insei tObj ect ( 0 , object, space)

105 } 106

107

108 /**

109 * Inεert an Ooject into persistent εtorage

110 * If a storage manager exception occurs, attempt to

111 * truncate the persistent ' orage and disable persistence

112 * θparam id The Object's persistent εtcrage ID

113 * θparam Object The Oo ect represented by xά

114 * θreturn The Object's persistent storage ID

115 * A return val e of PersistentStoreManager INVALID_OID indicates

116 an unsuccesε_ul attempt to insert the object

117 */

118 public int use tObject(ιrt i , Object object) {

119 return inse 'tOb ect ( id object, 0)

120 } 121

122

123 /**

124 * Inεert an Object into persistent storage

125 * If a storage manager exctotion occurs, attempt to

126 * truncate the persistent storage and disable persistence

127 * θparam id The Object's persistent storage ID

128 * Sparam Object The Object represented by id

129 * Sparam space The add tional space in byteε to oe preallocated

130 * for this object

131 * A return value of PersistentStoreManager INVALID_OID indicates

132 * an unsuccessful attempt to insert the object

133 */

134 public int insertObject ( t id, Object object, int space) {

135 if (persistenceManager == null) 136 return PersistentStoreManager INVALID_OID,

137

138 try {

139 if (id == 0)

140 return persistenceManager insertObject (object , space),

141 return -ersistenceM nager insertObject cid, object, space)

Mon Nov 11 16:23: LS 1996 4

142 } catch (Pe sistentStoreDuplicateObjectException el) {

143 try {

144 id = persisterce._'janager findObject (object) ,

145 if (_d '= PersistentStoreManager INVALID_OID) {

146 persistenceManager updateObject ( id object),

147 eturn id

148 }

149 } catch (Pers εtentStoreException e2) {

150 System out prmtln (' insertObject duplicate object found' + e2 getMessage ()) ,

151 e2 printStackTrace () ,

152 truncateFileStore () ,

153 perSiStencefanaπ-r = null

154 }

155 } catch vPersistentStorelnvalidOb ectException e3 ) {

156 System out println (' insertObject invalid ID" + e3 getMessage ()) ,

157 e3 printStackTrace () ,

158 } catch cPerεiεtentStoreException e4) {

159 System out ormtln (' insertObject can't insert object " + e4 getMessage () )

160 e4 prmtΞtac-cTrace (

161 truncateFileStore!)

162 pers¹ εtenceManacer - ^IJII

163 }

164 return Pers^tεntStcre atager INVALID_OID

165 }

166

167

168 /**

169 * Fetch an Object from perε tent εtorage

170 * If a εtorage manager exception occurs, attempt to

171 * truncate the perεiεtent εtorage and disable oerεiεtence

172 * θparam id The Object ε oerεistent storage IP

173 * θreturn Object The Object represented by id, or null,

174 * if the Object -.as not fcu-d persistent storage

175 */

176 public Object fetcnOoject ( t id) {

177 if (persistenceManager -- null)

178 return null

179

180 try {

181 retirn persistenceManager fetchObjec ( id) ,

182 } catch (^cersιstentStore;bj ectNotFoundException el) {

183 S^ystem out println (" fetchObject Object not found in persistent store, ID = " + id),

184 } catch (PersistentStorelnvalidObjectException e2) <

185 System out prm_.n (' fetchObject invalid ID" + e2 getMessage ()) ,

186 e2 printStackTrace!),

187 } catch (PersistentStoreException e3) {

188 Syεter out prmtln (' f etchObject can't fetch object ' + e3 getMessage ()) ,

Mon Nov 11 16:23:13 1996 5

189 e3 printStackTrace (j

190 truncateFileStore))

191 persistenceManager = null,

192 }

193 return null

194 }

195 196

197 /**

210 persistenceManager uciateObj ect ( lα object)

211 return t.ue

212 } catch (Persiεter tStoreCojectNotFoundException el) {

213 System out pr tln ( uodateObject Object not found in persistent store, ID = + id)

214 try t

215 pe sιεtence^Manage - insertObject ( id object) 215 ret rn true

217 } catch I'erSxStentStoreExceotion e2) {

218 Sy^tfe"- out oπnt n( uodateObject can t mεert object * e2 getMessage () )

219 e2 c mtStacKTrace O

220 truncateFi leStore ( )

221 per= εtenceManager = nul l

222 }

223 } catch (Perε_εtentStoreInvalιdObjectExceptιon e3 ) {

224 Ξyε-em out prmtln (' pdateObject invalid ID + e3 getMeεεage ( ) )

225 e3 cintStacKTr -te()

226 } catch (Pei sistentStoreException e4) {

227 Syster out prmtln( uoαateObject can t update object + e4 getMessage ()) ,

228 e4 printStackTrace (

229 truncateFileStore ()

230 persisterceManager = null

231 }

232 return fa_εe

233 234 235

Mon Nov 11 16:23:16 1996 7

283 try {

284 persistenceManager . truncateFileStore () ;

285 return true;

286 } catch (Exception e) {

287 Syste_" . out .println (' runcateFileStore : can't truncate εt~re " + e . getMessage ()) ;

288 e .pr _ntStackTrace ( )

289 persistenceManager - null;

290 return alεe;

291 }

292 } 293

294 /**

295 * Return a reference to the persistent storage manager.

296 */

297 public PersistentStoreManager getPersiεtenceManager ( ) {

298 return persistenceManager;

299 }

300 ) 301 302 3 03 304

Mon JJJOV 11 16 : 25 : 18 1996 6

236 /**

237 * Delete an cbject from persistent storage

238 * If a storage manager exception occurs, attempt to

239 * truncate the persistent storage and disable persistence

240 * θparam id The Object's oers.stent storage ID

241 * θreturn P boolean md.cating if the deletion was successful

242 */

243 public ooolean de.eteObject nt id) {

244 if (persistenceManager -= null)

245 return fa se 246

247 try {

248 persist enceManaqe.. u.-_eteOb ec t ( id)

249 return true

250 } catch (Fers_J.stentStoreC-]^cctNct^roun Exceptiⁿn el) ι

251 Syεtem out prm ±n( deleteObject Object net found _n persistent εtore ID = + id)

252 > catch (Pel sistentStor^p validOb ectExceotion e2) {

253 Syεtem out pnn_l- ( deleteObject lt'.ahd ID + e2 getMessage () )

254 e2 trmtStackTrac=()

255 } catch (PersistentStoreException e3) {

256 Syster cut prmtln ( oeleteOb ect can t delete object + e3 getMessage () )

257 e3 printStackTrace (

258 truncateF_leΞtore ( )

259 persistenceManager = null

260 }

261 return fa.se

262 } 263

264

265 /**

266 * Diεaole stor e cf ob ectε m oersistent store This method

267 * a.so tmnc?--'-

268 */

269 publ_c void d_ ->-ι-_>() /

270 truncateFileStore ( )

2^""1 nersistencc '?nager = p_u 1

272 }

273

276 * Truncate the persistent s-orage file to 0 bytes If a storage manager

277 * exception o_^cu^s disable persistence

278 */

279 public boolean truncateFileStore ( ) {

280 if (persistenceManager == null)

281 return raise 282

Mon Nov 11 16:33:05 1996 1

1 /* $Header /com/me cca/hsl/util/UmquelD Java 1 10/15/96 7 20a Billp $

3 ^** Copyright 1996 Honzc- Systems Laboratory, Mitεubiεhi Electric

4 * Information C--ter America

5 * All πghtε reserve:.

6 *

7 * CONFIDENTIAL AND

8 *

9 * DESCRIPTION

10 * This claεε generates IDs tnat are uniαue across d.^f-ibuted systems

11 * $Log /com/meitca/hεl 'uti _/UnιqueID java $ 12

13 * 1 10/15/96 7 20a Billp

14 */ 15

16 package com meitca hsl uti

17

18 import java util *,

19

20 import java net InetAddissε

21

22 /**

23 * This class generates IDs tnat are unique within a Java VM

24 * It is used by clasεeε tnat need to generate unique IDs

25 *

26 * Sauthor Noemi Paciorek

27 */

28 public class UmαuelD f 29

30 // Claεs variables

31 /** A counter used generating IDs */

32 protected εtatic long ID u " = 0 33

34 /** A unique ID .epresentng the host * /

35 protected εtatic String host 36

37 // Static initializer

38 static {

39 /*

40 * Try to obtain tne host's name and IP address If this fails,

41 * construct a pseudo-random name and hope for the best¹ (Of course,

42 * this εnould rever happen )

43 */

44 try {

45 host = InetAddress getLocalHoεt ( ) toStringO,

46 } catch 'Exception e) {

47 hoεt = ' 1-OSTID " + new Random () nextLong () ,

Mon Nov 11 16:33:05 1996 2

48 }

49 }

50 51

52 // Constructors

53 // No accessible constructors

54 /**

55 * Protected Default Ccnctructor for UmquelD

55 * This class never need; to be instantiated since all its variables 57 * and methods are static 53 * Sexception IllegalAcceεεExcept ion Whenever called

59 */

60 protected Unique D(;

61 throws Illega_-ccessE-_' ception { 62

63 System out .pr_ntin ( 'Default constructor called for UmquelD" ) ,

64 throw new IllegalAccessException ( "UmquelD default constructor"),

65 } 66 67

68 // Class methodε

69 /**

70 * Thiε method attempts to create an ID that lε unique across

71 * Java VMs . The ID is created from- the hostname, an application type

72 * (e.g , agent), the current time in mε , and the virtual memory

73 * address of tn cbject being created 74

75 * θparam type A String containing an application type, e g , "agent"

76 * θparam objpct The this" reference of the calling object

77 */

78 public εtatic itr g getN<= xtID (String type, Object object) {

79 return (host + ' '' + type + nextlDNumO + '/" +

80 Syεtem currer tTimeMillis ( ) + Integer toHexStnng (object hashCode ( ) ) ) ,

81 } 82

83

84 private static final .-.mchronized long nextlDNumO {

85 return ^IDNu , 85 } 87 88 }

Claims

- ϋtC, _CLAIMS What is claimed is:

1. In a computer network including at least a first computer and a second computer, an apparatus for performing a task in a second computer, comprising: a routine that generates a mobile agent object in the first computer, the mobile agent including both data and executable code; a protocol for transmission of the mobile agent from the first computer to the second computer, wherein execution of the mobile agent in the second computer following such transmission prompts the task to be performed in the second computer; and an itinerary containing a reference to each destination computer to which the mobile agent is designated to migrate and a reference to a method associated with each respective destination computer reference, the respective method being invoked when the mobile agent is present on the respective destination computer.

2. The apparatus of claim 1 wherein the transmission protocol includes a routine in the first computer for serializing the mobile agent to generate a stream of data therefrom.

3. The apparatus of claim 2 wherein the transmission protocol includes a routine in the second computer for deserializing the stream of bytes to regenerate the mobile agent therefrom. '

4. The apparatus of claim 1 wherein the task is data gathering, and wherein the mobile agent is transmitted back to the first computer from the second computer following completion of such data gathering.

The apparatus of claim 1 wherein the mobile agent migrates to a plurality of destination computers within the computer network.

6. The apparatus of claim 1 wherein at least one destination computer reference is a Uniform Resource Locator.

7. The apparatus of claim 1 wherein at least a portion of the executable code required for invoking the method is retrieved from a mobile codebase portion of the executable code included in the mobile agent.

8. The apparatus of claim 7 wherein the mobile agent includes a reference to a home codebase located on the first computer, the reference being employed to retrieve required executable code which is not present in the mobile codebase.

9. The apparatus of claim 8 wherein required executable code is sought first in the computer on which the mobile agent is executing, then in the mobile codebase, and finally on the home codebase.

10. The apparatus of claim 8 wherein a new thread is formed for execution of the mobile agent in the destination computer following receipt of the mobile agent, and wherein a security feature prevents the mobile agent from operating outside a scope assigned to such thread.

11. The apparatus of claim 8 wherein the mobile agent further includes sub-objects.

12. The apparatus of claim 1 wherein a persistent local copy of the mobile agent is stored following receipt of the mobile agent, and wherein such copy is overwritten with an updated persistent copy following agent execution. - .€. , _

13. In a computer network including at least a first computer and a second computer, a method for performing a task in a second computer, comprising the steps of: generating a mobile agent object in the first computer, the mobile agent including both data and executable code; transmitting the mobile agent from the first computer to the second computer; receiving the mobile agent in the second computer; and executing the mobile agent in the second computer in accordance with an itinerary which contains a reference to each destination computer to which the mobile agent is designated to migrate and a reference to a method associated with each respective destination computer reference, the method associated with the second computer being invoked when the mobile agent is present on the second computer.

14. The method of claim 13 including the further step of serializing the mobile agent to generate a stream of data therefrom in the first computer.

15. The method of claim 14 including the further step of deserializing the stream of bytes to regenerate the mobile agent therefrom in the second computer.

16. The method of claim 13 wherein the task is data gathering, and including the further step of transmitting the mobile agent back to the first computer from the second computer following completion of such data gathering.

17. The method of claim 13 including the further step of causing the mobile agent to sequentially migrate to a plurality of destination computers within the computer network.

18. The method of claim 13 including the further step of employing a Uniform Resource Locator as one of the at least one destination computer reference.

19. The method of claim 13 including the further step of retrieving at least a portion of the executable code required for invoking the method from a mobile codebase portion of the executable code included in the mobile agent .

20. The method of claim 19 wherein the mobile agent includes a reference to a home codebase located on the first computer, and including the further step of employing the reference to retrieve required executable code which is not present in the mobile codebase.

21. The method of claim 20 including the further step of searching for required executable code first in the computer on which the mobile agent is executing, then in the mobile codebase, and finally on the home codebase.

22. The method of claim 21 including the further step of forming a new thread in the destination computer for execution of the mobile agent following receipt thereof, and wherein a security feature prevents the mobile agent from operating outside a scope assigned to such thread.

23. The method of claim 21 including the further step of inserting sub-objects into the mobile agent.

24. The method of claim 13 including the further step of storing a persistent local copy of the mobile agent following receipt thereof, and overwriting such copy with an updated persistent copy following agent execution.

25. In a computer network including at least a first computer and a second computer, an apparatus for performing a task in a second computer, comprising: a routine that generates a mobile agent object in the first computer, the mobile agent including both data and executable code; a protocol for transmission of the mobile agent from the first computer to the second computer, wherein execution of the mobile agent in the second computer following such transmission prompts the task to be performed in the second computer, at least a portion of the executable code required for execution being retrieved from a mobile codebase portion of the executable code included in the mobile agent; and a reference to a home codebase located on the first computer, the reference being employed to retrieve required executable code which is not present in the mobile codebase.

26. The apparatus of claim 25 wherein the transmission protocol includes a routine in the first computer for serializing the mobile agent to generate a stream of data therefrom.

27. The apparatus of claim 26 wherein the transmission protocol includes a routine in the second computer for deserializing the stream of bytes to regenerate the mobile agent therefrom.

28. The apparatus of claim 25 wherein the task is data gathering, and wherein the mobile agent is transmitted back to the first computer from the second computer following completion of such data gathering.

29. The apparatus of claim 25 wherein the mobile agent migrates to a plurality of destination computers within the computer network.

30. The apparatus of claim 29 wherein the mobile agent further includes an itinerary containing a reference to each destination computer to which the agent is designated to migrate and a reference to a method associated with each respective destination computer reference, the respective method being invoked when the mobile agent is present on the respective destination computer.

31. The apparatus of claim 30 wherein at least one destination computer reference is a Uniform Resource Locator.

32. The apparatus of claim 25 wherein required executable code is sought first in the computer on which the mobile agent is executing, then in the mobile codebase, and finally on the home codebase .

33. The apparatus of claim 25 wherein a new thread is formed for execution of the mobile agent in the destination computer following receipt of the mobile agent, and wherein a security feature prevents the mobile agent from operating outside a scope assigned to such thread.

34. The apparatus of claim 25 wherein the mobile agent further includes sub-objects.

35. The apparatus of claim 30 wherein a persistent local copy of the mobile agent is stored following receipt of the mobile agent, and wherein such copy is overwritten with an updated persistent copy following agent execution.

36. In a computer network including at least a first computer and a second computer, a method for performing a task in a second computer, comprising the steps of: generating a mobile agent object in the first computer, the mobile agent including both data and executable code; transmitting the mobile agent from the first computer to the second computer; receiving the mobile agent in the second computer; retrieving at least a portion of the executable code required for invoking the method from a mobile codebase portion of the executable code included in the mobile agent; employing a reference to a home codebase located on the first computer to retrieve required executable code which is not present in the mobile codebase; and

executing the mobile agent in the second computer such that the mobile agent prompts the task to be performed in the second computer.

37. The method of claim 36 including the further step of serializing the mobile agent to generate a stream of data therefrom in the first computer.

38. The method of claim 37 including the further step of deserializing the stream of bytes to regenerate the mobile agent therefrom in the second computer.

39. The method of claim 36 wherein the task is data gathering, and including the further step of transmitting the mobile agent back to the first computer from the second computer following completion of such data gathering.

40. The method of claim 36 including the further step of causing the mobile agent to sequentially migrate to a plurality of destination computers within the computer network.

41. The method of claim 40 wherein the mobile agent further includes an itinerary which contains a reference to each destination computer to which the agent is designated to migrate and a reference to a method associated with each respective destination computer reference, and including the further step of invoking the method associated with the respective destination computer when the mobile agent is present on the respective destination computer.

42. The method of claim 41 including the further step of employing a Uniform Resource Locator as one of the at least one destination computer reference.

43. The method of claim 36 including the further step of searching for required executable code first in the computer on which the mobile agent is executing, then in the mobile codebase, and finally on the home codebase.

44. The method of claim 36 including the further step of forming a new thread in the destination computer for - L^-\ _

execution of the mobile agent following receipt thereof, and wherein a security feature prevents the mobile agent from operating outside a scope assigned to such thread.

45. The method of claim 36 including the further step of inserting sub-objects into the mobile agent.

46. The method of claim 41 including the further step of storing a persistent local copy of the mobile agent following receipt thereof, and overwriting such copy with an updated persistent copy following agent execution.