JP2007011569A - Duplex communication system and method for selecting server - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique that enables a client to determine a destination server in a system with double servers, while quickening the process of connecting the client to the servers. <P>SOLUTION: A relay node has a table 300A in which IP addresses for clients are held in association with a preferred server, and a table 300B in which other IP addresses for clients are held in association with an alternative server. The client holds table information that shows the relationship between each server and each table. When entering into an operating state because of the stop of the preferred server, the alternative server instructs the relay node to switch the table for reference to the table related to itself. When an IP address is requested by the client, the relay node allocates the IP address to the table to be referred to at the present time. The client determines the server with which the IP address allocated is associated, and executes communication, with the server serving as a destination. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a duplex communication system in which an alternative server is prepared for a server normally used by a client, and in particular, a duplex communication system in which a client and a server are connected to separate networks via a relay node such as a router. About.

  When a client communicates in a system in which servers are duplicated, the client first tries to connect to a service server deployed for normal use. If that fails, that is, the service server is stopped due to a failure or the like. In this case, the procedure of changing the connection destination and accessing the other alternative server has been common. However, in this procedure, since the client tries to connect regardless of the operating status of the regular server, there are inconveniences that when the regular server is stopped, unnecessary access occurs and the client connection process takes time.

Therefore, as a technique for dealing with the inconveniences described above on the server side, for example, there is one described in Patent Document 1 described later. In the method described in Patent Document 1, in a system in which servers are duplicated, when the service by the first server is stopped, the second server uses an identifier for identifying a device connected to the network. Change to that of the server, so that the second server continues the same service as the first server.
JP 2003-196172 A

  According to the method described in Patent Document 1, the client can receive a service promptly without being aware of the connection destination server, but does not actually start communication as to which server is connected. As far as it is difficult to grasp on the client side. Therefore, for example, when the management server is different between the regular server and the alternative server, the above method is not suitable for applications where it is necessary to grasp the connection destination in advance on the client side.

  The present invention has been made in view of the above problems, and provides a method capable of grasping a connection destination server from the client side while speeding up a connection process from the client to the server in a system in which servers are duplicated. With the goal.

  The duplex communication system of the present invention includes a client device, two systems of server devices that operate alternately, and a relay device that connects between the server device and the client device. The relay device assigns an IP address to the client device. Means for assigning, and means for storing IP address candidates to be assigned to the client device in association with each server device, and each server device assigns an IP address associated with the own device to the client device when the alternative operation is started. Means for instructing the relay apparatus to allocate to the client apparatus, the client apparatus storing means for storing table information indicating associations between IP address candidates and the server apparatuses, and the server apparatus of the two systems. Select the server device corresponding to the IP address assigned by the relay device as the connection destination. And a means for.

  In the server selection method of the present invention, a relay device that relays communication between two systems of server devices that perform alternative operations and a client device stores IP address candidates to be assigned to the client device in association with the server devices, The client device stores table information indicating the association between IP address candidates and each server device, and when each server device starts an alternative operation, the client device assigns an IP address associated with the own device to the client device. Instructing the relay apparatus, the client apparatus requests the IP address of the own apparatus to the relay apparatus, and the relay apparatus notifies the client apparatus of an IP address corresponding to the instruction from any server apparatus The client device is notified by the relay device of the two systems of server devices Select a server device corresponding to the P address as the destination is a method of executing communication with the server device.

  The basic concept of the present invention will be described with reference to FIG. In the illustrated system, the client 40 connected to the LAN 70 connects to the WAN side regular server 10A or the alternative server 10B via the relay node 30 such as a router. The relay node 30 associates an IP address candidate prepared for the client 40 with the primary server 10A in association with the pooled server 10A, and associates an IP address candidate with a value different from the previous one with the alternative server 10B. The pool IP table 300B to be held is held. The client 40 holds table information indicating the relationship between each server and the pool IP table.

  When the primary server 10A and the alternative server 10B enter the operating state by stopping the other, the relay server 30 instructs the relay node 30 to switch the pool IP table (300A or 300B) to be referred to to a table related to itself. give.

  When an IP address is requested from the client 40 connected to the LAN 70, the relay node 30 recognizes an assignable IP address from the pool IP table (300A or 300B) to be referred to at this time, and notifies the client 40 of this. .

  The client 40 determines whether the IP address assigned from the relay node 30 corresponds to the regular server 10A or the alternative server 10B using the table information, and determines the server (10A or 10B) recognized based on the determination result. Execute communication as the connection destination.

  According to the present invention, since any of the two server apparatuses is associated in advance with each of the IP address candidates held by the relay apparatus, the IP address assigned to itself when the client apparatus connects to the server apparatus. Based on this, it is possible to grasp which server device is the connection destination.

  FIG. 2 shows a configuration of an embodiment according to the present invention. The client 40 according to the embodiment described below is a portable information terminal such as a personal computer or a mobile phone having a wireless LAN function, and wireless LAN communication with the access point 30 corresponding to the relay device of the present invention. Communicate. In FIG. 2, one access point 30 and one client 40 are shown for simplification of explanation, but there may be a plurality of each.

  The access point 30 is communicably connected to the regular server 10A and the alternative server 10B of the LAN 60 in the WAN, and the pool IP table 300A associated with the regular server 10A and the pool IP table associated with the other alternate server 10B. 300B. Each pool IP table (300A and 300B) is an information table stored in a storage mechanism (not shown) of the access point 30, and has different address sequences between the tables as candidates for IP addresses to be assigned to the client 40. .

  The alternative server 10B of this embodiment is placed in a standby state unless the operation of the normal server 10A is stopped due to a failure or the like, and starts the alternative operation when the operation of the normal server 10A is stopped. A method conventionally known in the art is used to switch the operation between the two. For example, the operation status is monitored by the alternative server 10B periodically sending a PING command to the active server 10A. During the monitoring, when the response to the PING command cannot be obtained from the regular server 10A, the substitute server 10B determines that the operation of the regular server 10A has stopped, and starts its own substitute operation.

  FIG. 3 shows functional configurations of the regular server 10A and the alternative server 10B. Each server uses an alternative detection unit 11 that detects an alternative timing by monitoring the operation status of the other using the above-described method, and a pool IP table for the access point 30 when the alternative operation of the own device starts. It includes a table switching processing unit 12 that gives a switching instruction (300A and 300B) and a registration processing unit 13 that supplies registration information 14 including table information to the client 40 in a registration process described later.

  These functional configurations are common to the regular server 10A and the alternative server 10B, and correspond to functions realized by each server executing a program stored in a storage mechanism (not shown). By making the functional configuration common to both servers, the alternative server 10B can be continuously operated even after the recovery of the regular server 10A, and the alternate server 10B can be operated to be monitored by the regular server 10A. Thereby, it is possible to avoid stopping the service for the server switching operation.

  As a communication technique applied to the switching instruction by the table switching processing unit 12, for example, Telnet or the like generally used for remote control of an access point may be adopted.

  FIG. 4 shows a functional configuration of the access point 30. The access point 30 receives an IP address from the server 10A and the alternative server 10B and stores the address allocation unit 31 for notifying the client 40 of an IP address and security information for wireless LAN communication with the client 40. Part 32.

  The address allocation unit 31 refers to the pool IP table (300A or 300B) corresponding to the instruction from the regular server 10A or the alternative server 10B, and notifies the client 40 of an IP address that can be allocated. This notification is executed based on a conventionally known DHCP (Dynamic Host Configuration Protocol) that defines an automatic IP address assignment function.

  FIG. 5 shows a functional configuration of the client 40. The illustrated configuration corresponds to a function realized by the client 40 executing a program stored in its own storage mechanism (not shown). The address acquisition unit 41 acquires its own IP address from the access point 30 by DHCP. The server selection unit 42 determines a server associated with the acquired IP address, and executes communication using the server as a connection destination. The registration processing unit 43 acquires and stores registration information 44 including table information by a registration process performed in advance with the server (10A or 10B).

  FIG. 6 shows an example of table information acquired by the client 40. The table information is information indicating the relationship between each pool IP table (300A and 300B) of the access point 30 and each server (10A and 10B). In the example shown in FIG. 6, the service server 10A is associated with the address series “192.168.100.1 to 192.168.100.128” as IP address candidates to be assigned to the client 40, and is replaced with the address series “192.168.100.129 to 192.168.100.255”. The server 10B is associated. In the table information, the IP address of each server (10A and 10B) is also registered for the connection process of the client 40.

  Here, with reference to FIG. 7, the procedure of the above-described registration processing for the access point 30 and the client 40 will be described. In the example shown in the figure, the state where the common server 10A performs the processing is shown, but the alternative server 10B may perform the processing. The common server 10A uses the above-described Telnet or the like for the access point 30 to provide security information such as a WEP key and SSID for wireless LAN communication, and IP address candidates to be stored in each pool IP table (300A and 300B). sign up.

  In addition to the security information such as the WEP key and SSID described above, setting information for enabling DHCP, table information as shown in FIG. At this time, the communication between the regular server 10A and the client 40 is performed, for example, by infrared communication conforming to IrDA (Infrared Data Association), thereby simplifying the registration effort.

  The operation procedure of this embodiment will be described with reference to the sequence diagram shown in FIG. First, the registration process of the access point 30 and the client 40 is completed in advance according to the procedure described with reference to FIG. 7 (steps S1 and S2).

  When the substitute server 10B detects that its operation has stopped while monitoring the service server 10A by using the PING command or the like (step S3), the substitute server 10B starts the substitute operation and gives an instruction to switch the table to the access point 30. (Steps S4 and S5). Specifically, control is performed so that the table to be referred to by the access point 30 is switched from the pool IP table 300A to the pool IP table 300B.

  Thereafter, when the client 40 is activated in the wireless LAN and an IP address is requested from the client 40 to the access point 30 (step S6), the access point 30 stores the previously switched pool IP table 300B. The IP address that can be assigned is determined by referring to (step S7). As a result, the IP address associated with the alternative server 10B such as “192.168.100.129” (FIG. 6) is notified to the client 40 (step S8).

  When the client 40 acquires the IP address from the access point 30, the client 40 selects a connection destination by determining which server the IP address is associated with based on table information as shown in FIG. Step S9). Here, it is recognized that the acquired IP address is associated with the alternative server 10B. The client 40 refers to the IP address of the alternative server 10B in the table information and executes a connection to the alternative server 10B (step S10).

  As described above, according to the present embodiment, when the client 40 accesses the WAN, the server (10A or 10B) of the connection destination can be grasped in advance. As a result, an additional setting can be made for the client 40, for example, giving conditions to the connection to the alternative server 10B. In addition, since this system is configured to remotely execute registration and table switching for the access point 30 from the server side, the existing general point can be used as the access point 30. System installation costs can be reduced.

  In the above embodiment, the client device and the relay device according to the present invention communicate with each other by a wireless LAN. Instead, the two devices are connected by a wired LAN 70 as shown in FIG. It is also possible to implement the present invention. In that case, the security information handled in the registration process may be appropriately set according to the specifications of the wired LAN.

  The present invention is suitable for applications that require quick connection from a terminal to a server while taking countermeasures against the failure of the server, such as an order management system deployed in a retail store or a restaurant.

It is explanatory drawing for demonstrating the basic concept of this invention. It is a block diagram which shows the structure of embodiment by this invention. It is a block diagram which shows the function structure of the server of embodiment. It is a block diagram which shows the function structure of the access point of embodiment. It is a block diagram which shows the function structure of the client of embodiment. It is explanatory drawing for demonstrating the table information in embodiment. It is explanatory drawing for demonstrating the registration process of embodiment. It is a sequence diagram which shows the operation | movement procedure of embodiment.

Explanation of symbols

10A Regular server 10B Alternate server 30 Relay node 300A, 300B Pool IP table 40 Client

Claims (17)

A client device, two server devices that operate alternately, and a relay device that connects the server device and the client device;
The relay device includes means for assigning an IP address to a client device, and means for storing a candidate IP address to be assigned to a client device in association with each server device,
Each of the server devices has means for instructing the relay device to assign an IP address related to the own device to the client device when starting alternative operation,
The client device includes means for storing table information indicating an association between an IP address candidate and each server device, and a server device corresponding to the IP address assigned by the relay device among the two systems of server devices. And a means for selecting a connection destination. Each of the server devices has means for supplying security information and the table information to the client device,
The duplex communication system according to claim 1, wherein the client device has means for acquiring the security information and table information from any server device.   The duplex communication system according to claim 2, wherein the client device acquires the security information and table information by infrared communication.   The duplex communication system according to any one of claims 1 to 3, wherein the client device and the relay device communicate with each other by wireless LAN communication. A client device that can be connected to a relay device that relays communications to two systems of server devices that operate alternately.
Means for storing table information indicating an association between IP address candidates and each server device, and means for selecting a server device corresponding to the IP address assigned by the relay device from among the two systems of server devices as a connection destination And a client device.   6. The client apparatus according to claim 5, further comprising means for acquiring security information and the table information from one of the two systems of server apparatuses.   The client apparatus according to claim 6, wherein the security information and the table information are acquired by infrared communication.   The client device according to claim 5, wherein the client device communicates with the relay device by wireless LAN communication.   A program that causes a computer to function as the client device according to any one of claims 5 to 8. A server device that is connected to a relay device that relays communication to a client device and that operates alternately with other server devices,
Means for supplying table information and security information indicating the relationship between IP address candidates and each server device to the client device;
A server device comprising: means for instructing the relay device to assign an IP address related to the own device to the client device when the alternative operation is started.   A program causing a computer to function as the server device according to claim 10. A relay device that relays communication between two systems of server devices and client devices that perform alternative operations,
A relay device comprising: means for assigning an IP address to a client device; and means for storing a candidate for an IP address to be assigned to the client device in association with each of the server devices.   The relay apparatus according to claim 12, wherein the relay apparatus communicates with the client apparatus by wireless LAN communication. A relay device that relays communication between the server device and the client device of the two systems that perform alternative operations mutually stores IP address candidates to be assigned to the client device in association with each server device,
The client device stores table information indicating an association between IP address candidates and each server device;
When each server device starts an alternative operation, it instructs the relay device to assign an IP address related to the own device to the client device,
The client device requests the IP address of its own device to the relay device,
The relay device notifies the client device of an IP address corresponding to the instruction from any server device;
The server selection method, wherein the client device selects a server device corresponding to the IP address notified by the relay device from the two systems of server devices as a connection destination, and executes communication with the server device .   The server selection method according to claim 14, wherein the client device acquires security information and the table information from one of the two systems of server devices.   The server selection method according to claim 15, wherein the client device acquires the security information and table information by infrared communication.   The server selection method according to claim 14, wherein the client device and the relay device communicate with each other by wireless LAN communication.

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