Proxy response apparatus

• US 20040221207A1
• Filed: 11/07/2003
• Published: 11/04/2004
• Est. Priority Date: 03/19/2003
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Yokota, Daisuke, Noda, Fumio
• Granted Patent: US 7,518,983 B2
• Time in Patent Office: Days
• US Class Current: 714/48
• CPC Class Codes: G06F 11/2023 Failover techniques
• CPC Class Codes: G06F 11/2035 without idle spare hardware

Abstract

A proxy response apparatus 1 is equipped with a module that obtains and retains request messages and response messages exchanged between a client 3 and main and backup servers 2a and 2b, a module for detecting a failure in the main server 2a, a module for sending to the backup server 2b requests retained when a failure occurs in the main server 2a, a module for receiving responses from the backup server 2b, a module for detecting communications status between the client 3 and the main server 2a at the time the failure occurred, and a module for responding in place of the main server 2a in order to resume communicating state from the previous state.

Claims

1. A proxy response apparatus connected to at least one client and a plurality of servers through a communications network, the proxy response apparatus comprising:

a module that monitors occurrence of a failure in one of the plurality of servers that is processing request messages from the at least one client;

a module that obtains from the communications network packets composing a request message and a corresponding response message that are exchanged between the one of the plurality of servers and the at least one client and stores the packets; and

a managing module that obtains, when occurrence of a failure in the one of the plurality of servers is detected, a response packet that has not been sent to the at least one client from another of the plurality of servers without having a failure, and sends the response packet to the at least one client.

2. A proxy response apparatus according to claim 1, wherein the managing module comprises a module that receives a new request packet from the at least one client and sends the new request packet to the another of the plurality of servers without having a failure.

3. A proxy response apparatus according to claim 2, wherein the managing module comprises a module that receives a response packet corresponding to the new request packet from the another of the plurality of servers without having a failure, and sends the response packet to the at least one client.

4. A proxy response apparatus according to claim 3, wherein the managing module comprises a module that sends to the another of the plurality of servers without having a failure a request packet which has been sent from the at least one client but has not been responded by the one of the plurality of servers, and a module that receives from the another of the plurality of servers without having a failure a response packet corresponding to the request packet and sends the response packet to the at least one client.

5. A proxy response apparatus according to claim 3, wherein the managing module rewrites a transmission source address of the response packet to an address of the one of the plurality of servers that has a failure, and sends the response packet to the at least one server.

6. A proxy response apparatus according to claim 5, further comprising a storage module that stores addresses of the plurality of servers, wherein the transmission source address of the response packet is found by referring to the addresses of the plurality of servers stored in the storage module.

7. A proxy response apparatus according to claim 4, wherein the module that sends to the another of the plurality of servers without having a failure the request packet which has not been responded rewrites a transmission source address of the request packet to an address of the proxy response apparatus, and sends the request packet to the another of the plurality of servers without having a failure.

8. A proxy response apparatus according to claim 1, further comprising an obtaining and accumulating module that obtains and accumulates packets exchanged between the at least one client and the plurality of servers, and a restoring module that, when the module that monitors occurrence of a failure detects occurrence of a failure in the one of the plurality of servers, uses the packets accumulated in the obtaining and accumulating module to restore a state of the one of the plurality of servers at the time of occurrence of the failure with the another of the plurality of servers without having a failure.

9. A proxy response apparatus according to claim 8, wherein the restoring module comprises:

a module that, when the failure is detected in the one of the plurality of servers, rewrites a transmission destination address of packets that have been transmitted from the at least one client among the packets accumulated in the obtaining and accumulating module to an address of the another of the plurality of servers without having a failure, and sends the packets to the another of the plurality of servers without having a failure;

a module that receives response packets sent from the another of the plurality of servers without having a failure; and

a recognition module that recognizes, among the response packets, packets that have been already sent from the one of the plurality of servers that has the failure to the at least one client.

10. A network system having at least one client and a plurality of servers connected via a communications network, the network system comprising:

at least one load distribution device connected to the plurality of servers; and

a proxy response apparatus that, when a failure occurs in one of the plurality of servers that is processing a request message sent from the at least one client, makes another of the plurality of servers without having a failure continue processing the request message, and sends to the at least one client response packets that are results of processing the request message executed by the another of the plurality of servers,

wherein the at least one load distribution device comprises a module that, when the failure occurs in the one of the plurality of servers that is processing the request message sent from the at least one client, makes the another of the plurality of servers without having a failure process a new request message sent from the at least one client,

the proxy response apparatus comprises;

a module that monitors occurrence of a failure in the plurality of servers;

a module that obtains from the communications network packets composing a request message and a corresponding response message that are exchanged between the plurality of servers and the at least one client and stores the packets; and

a module that, when a failure is detected in one of the plurality of servers, obtains a response packet that has not been sent to the at least one client from another of the plurality of servers without having a failure, and sends the response packet to the at least one client.

11. A network system having at least one client and a plurality of servers connected via a communications network, the network system comprising:

a proxy response apparatus that, when a failure occurs in one of the plurality of servers that is processing a request message sent from the at least one client, makes another of the plurality of servers without having a failure continue processing the request message, and sends to the at least one client a response packet that is a result of processing the request message executed by the another of the plurality of servers;

at least one load distribution device that, when the failure occurs in the one of the plurality of servers that is processing the request message sent from the at least one client, makes the another of the plurality of servers without having a failure process a new request message sent from the at least one client.

12. A network system according to claim 11, wherein the proxy response apparatus comprises:

a module that monitors occurrence of a failure in the plurality of servers;

a module that obtains from the communications network packets composing a request message and a corresponding response message that are exchanged between the plurality of servers and the at least one client and stores the packets; and

a module that, when a failure is detected in one of the plurality of servers, obtains a response packet that has not been sent to the at least one client from another of the plurality of servers without having a failure, and sends the response packet to the at least one client.

13. A method for operating a proxy response apparatus that is connected to at least one client and a plurality of servers through a communications network, the method comprising the steps of:

monitoring occurrence of a failure in one of the plurality of servers that is processing request messages from the at least one client;

obtaining from the communications network packets composing a request message and a corresponding response message that are exchanged between the one of the plurality of servers and the at least one client and storing the packets; and

operating the proxy response apparatus to obtain, when occurrence of a failure in the one of the plurality of servers is detected, a response packet that has not been sent to the at least one client from another of the plurality of servers without having a failure, and send the response packet to the at least one client.

14. A method for operating a proxy response apparatus according to claim 13, wherein the step of operating the proxy response apparatus includes the steps of receiving a new request packet from the at least one client, and sending the new request packet to the another of the plurality of servers without having a failure.

15. A method for operating a proxy response apparatus according to claim 14, wherein the step of operating the proxy response apparatus includes the steps of receiving a response packet corresponding to the new request packet from the another of the plurality of servers without having a failure, and sending the response packet to the at least one client.

16. A method for operating a proxy response apparatus according to claim 15, wherein the step of operating the proxy response apparatus includes the steps of sending to the another of the plurality of servers without having a failure a request packet which has been sent from the at least one client but has not been responded by the one of the plurality of servers, and receiving from the another of the plurality of servers without having a failure a response packet corresponding to the request packet and sending the response packet to the at least one client.

17. A method for operating a proxy response apparatus according to claim 15, wherein the step of operating the proxy response apparatus includes the steps of rewriting a transmission source address of the response packet to an address of the one of the plurality of servers that has the failure, and sending the response packet to the at least one server.

18. A method for operating a proxy response apparatus according to claim 17, further comprising the steps of storing addresses of the plurality of servers, wherein the transmission source address of the response packet is found by referring to the addresses of the plurality of servers stored in the storage module.

19. A method for operating a proxy response apparatus according to claim 16, wherein the step of sending to the another of the plurality of servers without having a failure the request packet which has not been responded includes the steps of rewriting a transmission source address of the request packet to an address of the proxy response apparatus, and sending the request packet to the another of the plurality of servers without having a failure.

20. A method for operating a proxy response apparatus according to claim 13, further comprising the steps of:

obtaining and accumulating packets exchanged between the at least one client and the plurality of servers, and when the module that monitors occurrence of a failure detects occurrence of a failure in the one of the plurality of servers; and

restoring a state of the one of the plurality of servers at the time of occurrence of the failure with the another of the plurality of servers without having a failure by using the packets accumulated.

21. A method for operating a proxy response apparatus according to claim 20, wherein the step of restoring comprises the steps of:

when the failure is detected in the one of the plurality of servers, rewriting a transmission destination address of packets that have been transmitted from the at least one client among the packets accumulated to an address of the another of the plurality of servers without having a failure, and sending the packets to the another of the plurality of servers without having a failure;

receiving response packets sent from the another of the plurality of servers without having a failure; and

recognizing, among the response packets, packets that have been already sent from the one of the plurality of servers that has the failure to the at least one client.