System and method for transferring a session from one application server to another without losing existing resources

• US 6,058,424 A
• Filed: 11/17/1997
• Issued: 05/02/2000
• Est. Priority Date: 11/17/1997
• Status: Expired due to Term

• Current Assignee: SAP SE
• Original Assignee: International Business Machines Corporation
• Inventors: Verburg, Richard Lee, Wood, Donald Edwin, Dixon, Peggy PakFan, Shi, Danling
• Primary Examiner(s): Meky, Moustafa M.
• Application Number:
  US08/972,053
• Time in Patent Office: 897 Days
• Field of Search: 709/201, 709/220, 709/226, 709/228, 709/300, 714/4, 714/6, 714/13, 714/20
• US Class Current: 709/226
• CPC Class Codes: G06F 11/203 using migration
• CPC Class Codes: G06F 11/2033 switching over of hardware resources
• CPC Class Codes: G06F 11/2038 with a single idle spare processing component
• CPC Class Codes: G06F 11/2043 where the redundant components share a common memory address space

Abstract

The present invention allows a multimedia session to be transferred from one application server to another in the event that the original application server fails, and also allows a session to be cooperatively transferred from one application server to another, even though the original application server is still available for use. The new application server may be in the same multimedia computer (i.e. the same physical machine) as the original application server, or the new application server may be in a different computer. The session is transferred without losing existing resources, and callbacks that occur during the session takeover process are not lost. An application server which owns a multimedia session may enable that session for takeover, by using an Application Programming Interface (API). The API returns session takeover data which must be available to a new application server in the event of a takeover. The new application server uses the session takeover data to reconstruct information, including access information, regarding all resources necessary to keep the session executing.

Claims

1. A method for transferring a session, established between a first application server and a client, from the first application server to a second application server, comprising the steps of:

enabling the session for a transfer;

obtaining session takeover information from the first application server;

initiating the transfer when the first application server reaches a transfer causing condition; and

establishing the session in the second application server by reconstructing information regarding one or more session resources, wherein the information is reconstructed by the second application server using the session takeover information obtained from the first application server.

2. A method according to claim 1, wherein said establishing step further comprises the steps of:

accessing, by the second application server, the session takeover information;

determining, based on the session takeover information, one or more necessary resources which must be accessed by the second application server; and

reconstructing status and access information regarding the necessary resources in the second application server.

3. A method according to claim 2, wherein said determining step comprises the step of obtaining one or more active handles, wherein each active handle represents consumption of one or more session resources.

4. A method according to claim 1, wherein a transfer causing condition occurs when the first application server fails.

5. A method according to claim 1, wherein a transfer causing condition occurs when the first application server requests that the session be transferred from the first application server to the second application server.

6. A method according to claim 1, wherein said initiating step further comprises the step of queuing one or more callbacks for the session.

7. A method according to claim 6, further comprising the step of sending one or more queued callbacks to the second application server after the transfer is complete.

8. A method according to claim 1, wherein the first application server and the second application server are in separate computer systems.

9. A method according to claim 1, further comprising the steps of:

notifying the first application server that the transfer is being initiated; and

notifying the first application server that the transfer is complete.

10. A method according to claim 1, further comprising the step of notifying a control server that the transfer is complete.

11. A method for transferring a multimedia session, established between a first application server and a client, from the first application server to a second application server, comprising the steps of:

authorizing the session for transfer;

obtaining session transfer information from the first application server regarding one or more resources associated with the session in the first application server;

determining that the first application server has failed;

accessing the session transfer information; and

rebuilding status and access information regarding the resources associated with the session, in the second application server, wherein said rebuilding is based on the session transfer information obtained from the first application server.

12. A method according to claim 11, further comprising the steps of:

notifying a control server that the session is being transferred;

queuing, by the control server, one or more session callbacks during the transfer;

notifying the control server that the transfer is complete; and

sending, by the control server, the queued callbacks to the second application server.

13. A method for transferring a multimedia session, established between a first application server and a client, from the first application server to a second application server, comprising the steps of:

authorizing the session for transfer;

obtaining session transfer information from the first application server regarding one or more resources associated with the session in the first application server;

requesting, by the first application server, that the session be transferred to the second application server;

accessing the session transfer information; and

rebuilding status and access information regarding the resources associated with the session, in the second application server, wherein said rebuilding is based on the session transfer information obtained from the first application server.

14. A method according to claim 13, further comprising the steps of:

notifying a control server that the session is being transferred;

queuing, by the control server, one or more session callbacks during the transfer;

notifying the control server that the transfer is complete; and

sending, by the control server, the queued callbacks to the second application server.

15. A method according to claim 14, further comprising the steps of:

notifying the first application server that the transfer is being initiated; and

notifying the first application server that the transfer is complete.

16. An information handling system, comprising:

a client;

a multimedia server, including at least a control server and one or more application servers;

a network, connecting the client to the multimedia server, and providing means for establishing a session between the client and a first application server;

means for enabling the session for a transfer;

means for obtaining session takeover information from the first application server;

means for initiating the transfer when the first application server reaches a transfer causing condition; and

means for establishing the session in the second application server by reconstructing information regarding one or more session resources, wherein the information is reconstructed by the second application server using the session takeover information obtained from the first application server.

17. An information handling system according to claim 16, wherein said means for establishing further comprises:

means for accessing, by the second application server, the session takeover information;

means for determining, based on the session takeover information, one or more necessary resources which must be accessed by the second application server; and

means for reconstructing status and access information regarding the necessary resources in the second application server.

18. An information handling system according to claim 17, wherein said means for determining comprises means for obtaining one or more active handles, wherein each active handle represents consumption of one or more session resources.

19. An information handling system according to claim 16, wherein a transfer causing condition occurs when the first application server fails.

20. An information handling system according to claim 16, wherein a transfer causing condition occurs when the first application server requests that the session be transferred from the first application server to the second application server.

21. An information handling system according to claim 16, wherein said means for initiating further comprises means for queuing one or more callbacks for the session.

22. An information handling system according to claim 21, further comprising means for sending one or more queued callbacks to the second application server after the transfer is complete.

23. An information handling system according to claim 16, wherein the first application server and the second application server are in separate computer systems.

24. An information handling system according to claim 16, further comprising:

means for notifying the first application server that the transfer is being initiated; and

means for notifying the first application server that the transfer is complete.

25. An information handling system according to claim 16, further comprising means for notifying the control server that the transfer is complete.

26. A computer readable medium for controlling the transfer of a session, established between a first application server and a client, from the first application server to a second application server, comprising:

means for enabling the session for a transfer;

means for obtaining session takeover information from the first application server;

means for initiating the transfer when the first application server reaches a transfer causing condition; and

means for establishing the session in the second application server by reconstructing information regarding one or more session resources, wherein the information is reconstructed by the second application server using the session takeover information obtained from the first application server.

27. A computer readable medium according to claim 26, wherein said means for establishing further comprises:

means for accessing, by the second application server, the session takeover information;

means for determining, based on the session takeover information, one or more necessary resources which must be accessed by the second application server; and

means for reconstructing status and access information regarding the necessary resources in the second application server.

28. A computer readable medium according to claim 26, wherein said means for determining comprises means for obtaining one or more active handles, wherein each active handle represents consumption of one or more session resources.

29. A computer readable medium according to claim 26, wherein a transfer causing condition occurs when the first application server fails.

30. A computer readable medium according to claim 26, wherein a transfer causing condition occurs when the first application server requests that the session be transferred from the first application server to the second application server.

31. A computer readable medium according to claim 26, wherein said means for initiating further comprises means for queuing one or more callbacks for the session.

32. A computer readable medium according to claim 31, further comprising means for sending one or more queued callbacks to the second application server after the transfer is complete.

33. A computer readable medium according to claim 26, wherein the first application server and the second application server are in separate computer systems.

34. A computer readable medium according to claim 26, further comprising:

means for notifying the first application server that the transfer is being initiated; and

means for notifying the first application server that the transfer is complete.

35. A computer readable medium according to claim 26, further comprising means for notifying a control server that the transfer is complete.