CN106561032A - Message communication method based on XML - Google Patents

Abstract

The invention discloses a message communication method based on XML. According to the message communication method based on XML, an XML format encapsulation and analysis mechanism of communication messages of multiple Agent systems is achieved in a way of message transmission, reliable and effective transmission of messages is achieved through a message transfer synchronous control algorithm based on message priority.

Description

A kind of message communication method based on XML

Technical field

A kind of message communication method based on XML relates generally to computer communication aspect field.

Background technology

It is based on network technology, to will be distributed over the Agent on diverse geographic location based on multi-Agent distributed system In being integrated in the consistent environment in a time and space, by the communication between them and interoperability, knowledge and information sharing are realized, so as to complete the solution of complex task.Multi-Agent Distributed system is widely used in such as ecommerce, robot control, Production-Plan and scheduling different field.At present, with regard to multi-Agent The research of distributed system, is concentrated mainly on the communication modes for supporting cooperation, and proposes many cooperation Communication Models.Such as based on the hardened structure of black/white and message based Communication Model.In the multi-Agent Communication Model based on blackboard structure, blackboard provides common work area, Agent Information, data and knowledge can be exchanged.But when Agent number of network nodes increases, the data volume in blackboard can be exponentially increased, causing the communication efficiency of system reduces.In message based Communication Model, by using unified message transmission protocol between Agent, the defect of blackboard system is overcome, improve the ability to communicate of system.But, in the Communication Model of message, how to carry out the transmission and synchronization of message between Agent, it is ensured that the reliability and validity of communication, i.e., ensure that message is reliably submitted to minimum communication time in the case of communication；How to ensure that message is not limited by protocol responses structure, the flexibility for improving system communication remains a difficult point of research.

The main communication that multi-Agent distributed system is realized in the way of message transmission, by the encapsulation of XML forms and parsing using message the transmission of message is realized.Message after encapsulation supports the extension to it due to binding more information, therefore overcomes restriction of the protocol responses structure to message, improves the flexibility of messaging.While in order to keep Agent Between messaging space-time consistency, employ in message transmitting procedure based on the transmission synchronization control algorithm of message priority, it is ensured that the reliable effectively transmission of message.The framework of realizing of system emulation is finally given, and in Win2000 Checking is achieved in system using Java language.

The content of the invention

Retrieved without the application materials found with regard to this system aspects by national patent.

In multi-Agent distributed system, in order to realize the communication between Agent, it is desirable to which each Agent knows other Agent Title, mailing address, PORT COM, collaboration capabilities etc..Therefore, a Communication Agent module is designed in each simulation Agent.The module is responsible for all actions relevant with communication, while the module is also Agent Between an interface being communicated.Each communication module includes information table, message cache pool and a part of communication services manager three.Information table is used for recording Agent In some fundamental characteristics.Information table mainly includes following two parts：（1）Static information table：The static information of storage Agent itself, such as Agent marks, the performance of itself, IP addresses；（2）Multidate information table：Other Agent information under main memory communicating state.In each Agent Start with during other Agent communications, various communicating status informations can be registered in multidate information table, and these information are deleted when exiting, to keep the real-time update of multidate information table；Message cache pool：Agent For storing the message for sending and receiving；Communication services manager：The encapsulation of XML forms and parsing of main responsible message, message synchronization transmission control.Avoid the cause and effect mistake caused due to stationary problem.

Information table, message cache pool, communication services manager and other each several parts are defined as into respectively the form of Java classes；The message for sending is packaged into XML format files, is then transmitted.TCP/IP is adopted in bottom Communications protocol and socket mechanicss of communication realize many simulation Agents The communication of node.Specifically method of operating is:

1. the message encapsulation and parsing based on XML：1）In message transmission, the semantic content of message is the core of Agent communications.Mainly apply FIPA-ACL Message structure [5].By using FIPA-ACL Message, each Agent can be to other Agent Send request or ask service.FIPAACL message structures are a kind of message structures based on primitive, and 3 levels are divided into from outside to inside：envelope、content、message.envelope：The various additional informations of description message transmission, such as sender, recipient；content：The particular content of description message transmission；message：The various parameters of description message transmission, the coded format that such as message is used, agreement of transmission etc..

Every time message only carries out message request with service in the range of intrinsic primitive（As received（accept）, request（request）Deng）, autgmentability is poor.Therefore, in order to overcome restriction of the protocol responses structure to messaging.Herein this message structure is packaged into into XML forms.The advantage of XML forms is can be with self-defined many XML labelled elements, and XML elements can bind more information, and support extends to it.Meanwhile, the compression transmission of data is easily achieved during transmission, improve efficiency of transmission, that is, network traffics are saved, reduce communication time.Such as in message.dtd In extend the attribute of priority.

Message structure based on XML（message.dtd）It is as follows：

<! ELEMENT acl-message（Msg-type, msg-param）

<! ELEMENT msg-type（agree|request|refuse|accept-proposal|cancel）>

<! ELEMENT agree（#PCDATA）>

……

<! ELEMENT msg-param（#PCDATA）>

<! ATTLIST msg-param sender CDATA #REQUIRED

receiver CDATA #REQUIRED

content CDATA #REQUIRED

in-reply-to CDATA #REQUIRED

language CDATA #REQUIRED

priority CDATA #REQUIRED

>

For example：Agent A are asked（request）Agent B are pushed to a chest.

Transmission message structure（move.xml）It is as follows：

<xml version="1.0">

<! DOCTYPE acl-message SYSTEM "message.dtd">

<acl-message>

<msg-type> request</msg-type>

<msg-param sender="A"

receive="B"

content="action（agent-identifier：name B）（deliver box（loc 12）"

language="fipa-sl"

protocol="fipa-request"

reply-with="order567"

priority="5">

</msg-param>

</acl-message >。

2）The parsing of XML documents

Receiving terminal needs to parse XML documents to recognize specific request message content.The purpose of parsing seeks to read the data required for user from XML documents.The parsing to XML documents is realized using DOM resolvers [6].After document parsing, first determine whether to belong to which type of message, it is then corresponding according to message activation

Action.Analyzing step is as follows：

（1）In javax.xml.parsers.DocumentBuilderFactory In class, newInstance is called（）Method, generates a DocumentBuilderFactory object.

DocumentBuilderFactory factory =DocumentBuilderFactory.newInstance（）；

（2）Using factory Call newDocumentBuilder（）Method generates DocumentBuilder

Object.

javax.xml.parsers.DocumentBuilder Build=factory.newDocument-

Builder（）；

（3）build Object reference public Document parse（File f）The XML documents that method parsing f is specified, and the data with descendants's relation node are analyzed by Element type objects.

Org.w3c.dom.Document dom=build.parse（new File（move.xml））；

Element root=dom.getDocumentElement（）；

（4）Finally, the data call getElementByTagName for parsing（String）Method, recognizes each flag node content.In addition, for the node containing attribute will do special process, allowing the node object to call NamedNodeMapgetAttributes（）Method is parsing property content.

NodeList nodelist=root.getElementByTagName（“acl-message”）；

NamedNodeMap nnm=nodelist.item（i）.getAttributes（）；// the i-th knot

Point attribute.

2. communication services manager:1) the various affairs that mutually communication will be processed in Agent communication process are realized between simulation Agent.One communication services manager is set in each communication module.Communication services manager plays in systems central role as the hinge of message communication.Communications service management mainly includes the conversion of XML documents with parsing, Agent system administrations, Agent domain name supervisings and message transmitting procedure management.XML documents are changed and parsing：The XML forms encapsulation of completion message and the parsing of XML files；Agent domain name supervisings：Parse and inquire about the information such as title, address and the PORT COM of other Agent；Agent System administration：The cooperating of other intermodules of responsible simulation Agent inside；Message transmitting procedure is managed：Service in mainly completing to communicate is monitored and sent and the transmission control for receiving, such as message transmission Synchronization Control with thread management and message；For other Agent Distribution thread etc..

The function of communication services manager is realized with method by the class that is defined as follows.Service is monitored with thread management to be processed by run methods.Method doComm-Manage is used for the Synchronization Control management of completion message transmission.The XML forms encapsulation of message and parsing are respectively by CreateXml DoConverXml methods and parseXml methods in class is realized.

Communications service management class is defined as：

Class CommServer implements Runnable, IEventHandler

{ CreateXml crxml=new CreateXml（）；

public void setup（）{ // start service is monitored }

pulic void doCommManage（String message）{}

public void run（）{ // service is monitored and thread management }

public void sent（）

{ ZipOutputStream out=new ZipOutputStream（socket.getOutputStream（））；

out.putNextEntry（new ZipEntry（“message1.xml”））；

out.write（）；// flow write output after data compression；

}

public String receive（）{}

public void action（） {

synchronized（this）{}

// message processing procedure }

}。

2). it is to ensure simulation Agent communicating between nodes over time and space consistent, there is shown herein the transmission control algolithm based on message priority in view of the distributed feature of multi-Agent simulated environment.Packaged message XML file is allowed to enter transformation task ready queue according to priority height first.Priority determines according to transformation task urgency level.

System always allows the task of highest priority to start to perform.When a higher task of priority is reached, it is allowed to by current transmission task temporary suspension, and make high-priority task put into operation immediately.Adopting can meet in this way most urgent message prioritization transmission.If all of process all has identical priority initial value, enter first carry out at first.High-priority task is controlled using synchronized code block strategy when implementing, so as to ensure messaging over time and space consistent.In transmission, for the validity for ensureing to communicate, determined with minimum communication time when using local communication, when using telecommunication.

Claims (9)

1. a kind of message communication method based on XML is characterized in that（1）Static information table：The static information of storage Agent itself, such as Agent marks, the performance of itself, IP addresses；（2）Multidate information table：Other Agent information under main memory communicating state.

2. information table, message cache pool, communication services manager and other each several parts are distinguished according to claim 1

It is defined as the form of Java classes；The message for sending is packaged into XML format files, is then transmitted.

3., according to claim 2 by using FIPA-ACL message, each Agent can send request or ask service to other Agent.

4. XML format is packaged into this message structure according to claim 3.

5. this XML is parsed according to claim 4；Mainly in javax.xml.parsers.DocumentBuilderFactory classes, newInstance is called（）Method, generates a DocumentBuilderFactory object；

DocumentBuilderFactory factory =DocumentBuilderFactory.newInstance（）.

6. newDocumentBuilder is called using factory according to claim 5（）Method generates DocumentBuilder objects;

Javax.xml.parsers.DocumentBuilder build=factory.newDocument-Builder（）.

7. according to the build object reference public Document parse in claim 6（File f）The XML documents that method parsing f is specified, and the data with descendants's relation node are analyzed by Element type objects;

Org.w3c.dom.Document dom=build.parse（new File（move.xml））；

Element root=dom.getDocumentElement（）.

8. the data call getElementByTagName for being parsed according to claim 7（String）Method, recognizes each flag node content.

9. in addition, for the node containing attribute will do special process, allowing the node object to call NamedNodeMapgetAttributes（）Method is parsing property content；

NodeList nodelist=root.getElementByTagName（“acl-message”）；

NamedNodeMap nnm=nodelist.item（i）.getAttributes（）.