JP2004248228A - Service switchover apparatus, service provision node, communication system, program, and recording medium stored with the program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the continuity of service in a logical network (for example, a P2P network) independently of network topology. <P>SOLUTION: A service switchover apparatus 4 includes, on a logical network 5, an address conversion table 12 which retains logical network addresses and physical network addresses of nodes on the logical network 5; a service provision state supervisor 11 for supervising the service provision state of the service-providing node 2; and upon the detection of the service provision node 2 having disappeared from the logical network 5, an address converter 13 for converting (A) the logical network address and the physical network address of the service provision node 2 and (B) a logical network address, and a physical network address of a service provision spare node 3 substituted for the service-providing node 2, by referring to the address conversion table 12. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for continuing service in a logical network such as a peer-to-peer network.
[0002]
[Prior art]
As an alternative to a server-client model network configuration in which network management is centralized, a peer-to-peer (hereinafter abbreviated as P2P) large-scale network in which network participants connect to the network on an equal footing Is getting more and more attention. Recently, various services have been actively provided by using a P2P network. Here, a node that connects to the P2P network and provides a service is called a service providing node, and a node that receives the service is called a user node. Although the terms service providing node and user node are used, since they are P2P networks, they are equal as nodes connected to the network.
[0003]
Logical networks used by JXTA, which is a typical platform of P2P networks, provide users with greater ease of use and enable application developers to create applications more easily. For this reason, the connection in the physical network (such as TCP / IP) is concealed in the basic part of the logical network (for example, JXTANetwork), and does not depend on the structure of the physical network at all (for example, , Non-Patent Documents 1 and 2). This is also to enable users to participate in the P2P network regardless of the structure of the physical network and without having to be aware of the existence of the physical network. It is set independently.
[0004]
[Non-patent document 1]
Li Gong, "Project JXTA: A Technology Overview", [onne], jxta. org, April 25, 2001, [search date: January 31, 2003], Internet <URL: http: // java. sun. com / people / gong / papers / jxview. pdf>
[Non-patent document 2]
Takanari Hoshiai and 5 others, "Semantic Information Network Architecture", IEICE Transactions, B Vol. J84-B, No. 3, pp. 411-424, issued in March 2001 [0005]
[Problems to be solved by the invention]
However, in a logical network, if the service providing node loses network connectivity due to, for example, a failure in a device, the service providing node disappears from the logical network. That is, it does not exist on the logical network. Further, so far, most of logical networks are constituted by volunteer-based nodes, and the reliability of the nodes is low. For these reasons, at present, service continuity when providing services on a logical network is low.
[0006]
Therefore, an object of the present invention is to provide a service switching device, a service providing node, and a communication system capable of improving service continuity on a logical network.
[0007]
[Means for Solving the Problems]
The service switching device of the present invention is a service switching device provided on a logical network independent of a network topology, and an address conversion table that holds a logical network address and a physical network address of a node on the logical network; Service providing state monitoring means for monitoring the service providing state of at least one node on the logical network; and referencing the address translation table when the service providing state monitoring means detects a node where the service is not normally provided. Address conversion means for converting between a logical network address and a physical network address of the node, and a logical network address and a physical network address of a node which is a substitute for the node; A.
[0008]
A service providing node according to the present invention is a service providing node provided on a logical network independent of a network topology, and a server processing means for executing processing as a server for providing a service, and a service providing node provided by the own service providing node. Recovery notifying means for notifying the logical network of service recovery when returning to the state.
[0009]
That is, according to the present invention, in order to improve service continuity on a logical network, a spare service providing node is prepared in preparation for a time when a service cannot be provided, and the service provision by the service providing node is stopped. Then, the service provision can be continued by the service provision spare node.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating an example of a configuration of a communication system according to an embodiment of the present invention.
[0011]
A logical network 5 independent of the network topology of the physical network is set, and a user node 1 that receives a service, a service providing node 2 that provides a service, and a logical network 5 of the service providing node 2 And a service switching device 4 for switching between the service providing node 2 and the service providing spare node 3. The user node 1, the service providing node 2, the service providing spare node 3, and the service switching device 4 all exist on a logical network 5. The service providing spare node 3 prepares a function capable of providing the same service as the service provided by the service providing node 2 to prepare for the case where the service providing node 2 disappears from the logical network.
[0012]
The service switching device 4 includes a service providing state monitoring unit 11 for monitoring the service providing state of the service providing node 2, and an address for storing a logical network address and a physical network address of the service providing node 2 and the service providing spare node 3. When the service providing node 2 detects that the service providing node 2 does not provide the service, the logical network address and the physical network address in the packet transmitted / received between the user node 1 are referred to by referring to the address translation table 12. An address translator 13 for translating the network address into the address of the service providing spare node 3. As will be described later, when receiving the service restoration notification from the service providing node 2, the address conversion unit 13 stops the address conversion for the passing packet.
[0013]
The service providing node 2 and the service providing spare node 3 remain unchanged in that they have a function of providing a service to the user node 1. Therefore, each of the service providing node 2 and the service providing spare node 3 includes a server processing unit 21 that performs general processing as a server that provides a service and its own node (the service providing node 2 and the service providing spare node 3). And 3) a recovery notifying unit 22 that transmits a service recovery notification to the service switching device 4 when the service returns from a state in which the service cannot be provided to a state in which the service can be provided.
[0014]
Next, the operation of the communication system according to the present embodiment will be described. First, a process when the service providing node 2 disappears from the logical network due to some failure while the service providing node 2 is providing a service (normal time) will be described with reference to FIG.
[0015]
Normally, the user node 1 sends a service request packet to the service providing node 2 to the logical network 5, and the service request packet is sent to the service providing node 2 via the service switching device 4 as it is. The service providing node 2 generates and transmits a service request response packet corresponding to the service request. This service request response packet is also sent to the user node 1 as it is via the service switching device 4. At this time, the service providing state monitoring unit 11 of the service switching device 4 monitors the service providing state of the service providing node 2 by checking whether there is a normal service request response to the service request. Since the service request to the service providing node 2 does not always exist, the service providing state monitoring unit 11 periodically sends the service request to the service providing node 2 to confirm the normal response of the service providing node 2.
[0016]
Here, it is assumed that a failure or the like has occurred in the service providing node 2. In that case, a normal response to the service request is not returned. If a normal response is not returned and the timeout occurs, the service providing status monitoring unit 11 determines that the service providing node 2 has disappeared from the logical network 5 and notifies the address translating unit 13 of that fact. The address conversion unit 13 switches the access destination of the service request from the user node 1 to the service providing node 2 to the service providing spare node 3 by performing the address conversion.
[0017]
Next, a process when the service providing node 2 that has disappeared from the logical network 5 is restored will be described with reference to FIG.
[0018]
Since the service providing node 2 has disappeared from the logical network 5, the service request from the user node 1 is sent to the service providing spare node 3 via the service switching device 4, and the service request response from the service providing spare node 3 is sent. Is sent to the user node 1 via the service switching device 4. Here, assuming that the service providing node 2 recovers and enters the service providing state, the return notification unit 22 of the service providing node 2 transmits a service recovery notification packet to the service switching device 4. In the service switching device 4, upon receiving the service restoration notification, the address conversion unit 13 switches the service from the service providing spare node 3 to the service providing node 2 with the trigger as a trigger. More specifically, the address translation process performed when the service providing node 2 disappears from the logical network 5 is stopped.
[0019]
Thereafter, returning to the normal sequence, the service request from the user node 1 to the service providing node 2 is sent to the service providing node 2 as it is via the service switching device 4, and the service request response from the service providing node 2 is returned. Is sent to the user node 1 as it is via the service switching device 4.
[0020]
FIG. 4 illustrates the processing of the address conversion unit 13 of the service switching device 4.
Here, ID 101 is assigned as a logical network address and Address 101 is assigned as a physical network address to the user node 1, and ID 201 is assigned as a logical network address and Address 201 is assigned as a physical network address to the service providing node 2. It is assumed that ID 301 is assigned as the logical network address and Address 301 is assigned as the physical network address to the assigned service providing spare node 3. As a result, the logical network address and the physical network address of each of the service providing node 2 and the service providing spare node 3 are set in the address conversion table 12 of the service switching device 4 as illustrated. The address conversion unit 13 performs an address conversion on the packet based on the address conversion table 12.
[0021]
The packet 101a is a packet transmitted from the user node 1 with the service providing node 2 as a destination. The packet includes a payload in the logical network, and also includes a logical network address and a physical network address for each of the destination and the source. In particular, the packet 101a stores the logical network address and the physical network address of the service providing node 2 as the destination address.
[0022]
When such a packet 101a passes through the service switching device 4 when the service providing node 2 has disappeared from the logical network 5, the address conversion unit 13 causes the logical network address (ID 201) and the physical network address of the destination to be transmitted. (Address 201) are changed to the logical network address (ID 301) and the physical network address (Address 301) of the service providing spare node 3, respectively, and are output from the service switching device 4 as the packet 101b. Since the packet 101b reaches the service providing spare node 3, the packet transmitted from the user node 1 can reach the service providing spare node 3 although the destination address is rewritten.
[0023]
If the packet 101b is a service request packet, the service providing spare node 3 transmits a service request response packet to the user node 1. In the packet 301b transmitted from the service providing spare node 3, the logical network address (ID 301) and the physical network address (Address 301) of the service providing spare node 3 are set as source addresses. When the packet 301b passes through the service switching device 4, the address conversion unit 13 changes the source address of the packet 301b to the logical network address (ID 201) and the physical network address (Address 201) of the service providing node 2. Then, the packet is transmitted to the user node 1 as a packet 301a. As a result, at the user node 1, the packet appears to be coming from the service providing node 2, and therefore appears to be enjoying the service from the service providing node 2.
[0024]
In a normal state in which the service providing server 2 is in the service providing state, the packet 101a from the user node 1 reaches the service providing server 2 without being subjected to the address conversion processing in the address conversion unit 13. Further, the packet of the service response request from the service providing server 2 also reaches the user node 1 without undergoing the address conversion processing.
[0025]
As described above, according to the present embodiment, even when the service providing node 2 has disappeared from the logical network 5, the service switching device 4 switches the access request to the service providing spare node 3 so that the service providing node 2 can continue. Service can be enjoyed.
[0026]
Although the preferred embodiment of the present invention has been described above, the service providing node 2, the service providing spare node 3, and the service switching device 4 according to the above-described embodiment include a computer program for realizing them, and a server computer. It can also be realized by causing a computer to read the program and executing the program. Generally, the service providing node 2, the service providing spare node 3, and the service switching device 4 are realized by separate computers. A program for realizing the service providing node (and the service providing spare node) and the service switching device is read into a computer by a recording medium such as a magnetic tape or a CD-ROM, or via a network.
[0027]
These computers generally include a CPU (Central Processing Unit), a hard disk device for storing programs and data, a main memory, an input device such as a keyboard and a mouse, a display device such as a CRT, a magnetic tape, It comprises a reading device for reading a recording medium such as a CD-ROM, and a communication interface used for connection to a network. The hard disk device, main memory, input device, display device, reading device, and communication interface are all connected to the CPU.
[0028]
In these computers, a recording medium storing a program for realizing a server providing node (or a server providing spare node) is mounted on a reading device, the program is read from the recording medium, and stored in a hard disk device. By storing such programs in a hard disk device from a network via a communication interface, and then executing the programs stored in the hard disk device by a CPU, the program functions as a server providing node (or a server providing spare node). . Similarly, these computers mount a recording medium storing a program for realizing a service switching device on a reading device, read the program from the recording medium and store the program on a hard disk device, or store such a program on a network. After that, the program is stored in the hard disk device via the communication interface, and then the CPU executes the program stored in the hard disk device to function as a service switching device.
[0029]
【The invention's effect】
As described above, according to the present invention, in a logical network such as a P2P network, when a service providing node disappears from the logical network, it is immediately switched to an alternative service providing spare node, thereby greatly improving service continuity. It has the effect of improving.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of a configuration of a communication system according to an embodiment of the present invention.
FIG. 2 is a sequence diagram showing an operation when a service providing node disappears from a logical network.
FIG. 3 is a sequence diagram showing an operation when the service providing node is restored.
FIG. 4 is a diagram showing processing in an address conversion unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 User node 2 Service providing node 3 Service providing spare node 4 Service switching device 5 Logical network 11 Service providing state monitoring unit 12 Address conversion table 13 Address conversion unit 21 Server processing unit 22 Recovery notification unit

Claims (7)

A service switching device provided on a logical network independent of a network topology,
An address translation table that holds a logical network address and a physical network address of a node on the logical network;
Service providing state monitoring means for monitoring a service providing state of at least one node on the logical network;
When the service providing state monitoring means detects a node where the service is not normally provided, the logical network address and the physical network address relating to the node are referred to by referring to the address conversion table, and the replacement of the node is performed. Address translation means for translating between a logical network address and a physical network address of a node to be switched. 2. The service switching device according to claim 1, wherein the address conversion unit ends the address conversion process when notified of recovery from a node detected as a node that has not been provided normally. 3. A service providing node provided on a logical network independent of a network topology,
Server processing means for executing processing as a server providing a service;
Recovery notifying means for notifying the logical network of service recovery when the own service providing node returns to the service providing state. A logical network independent of the network topology,
An address translation table provided on the logical network and holding a logical network address and a physical network address of a node on the logical network, and monitoring a service providing state of at least one node on the logical network. Service providing state monitoring means, and when the service providing state monitoring means detects a node where a service is not normally provided, the logical network address and the physical network related to the node are referred to by referring to the address conversion table. A service switching device, comprising: an address, and an address translation unit that translates between a logical network address and a physical network address of a node that substitutes for the node.
Server processing means provided on the logical network for executing processing as a server providing a service, and recovery notifying means for notifying the logical network of service recovery when the own node returns to a service providing state A first node having:
A second node provided on the logical network as a substitute for the first node and having a server processing means for executing processing as a server that provides a service;
When the service providing state monitoring means detects that the first server has become unable to provide a service, an access request for the first node is connected to the second node by the address conversion means, A communication system, wherein a connection to the second node is returned to the first node when service restoration is notified from the first node. Computer
Service providing state monitoring means for monitoring at least one service providing state on a logical network independent of a network topology;
When the service providing state monitoring unit detects a node where a service is not normally provided, the service providing state monitoring unit refers to an address conversion table that holds a logical network address and a physical network address of a node on a logical network, and A program for functioning as an address conversion unit that converts between a logical network address and a physical network address of a node and a logical network address and a physical network address of a node that substitutes for the node. Computer
Server processing means for executing processing as a server providing a service,
A program for functioning as a recovery notifying means for notifying a logical network side independent of a network topology of service recovery when its own service providing node returns to a service providing state. A recording medium readable by a computer, the recording medium storing the program according to claim 5.

Images