Persistent cache synchronization and start up system

• US 6,061,714 A
• Filed: 05/07/1997
• Issued: 05/09/2000
• Est. Priority Date: 05/07/1997
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Meriwether, Teresa Anne, Housel, Barron Cornelius III, Shields, Ian Beaumont
• Primary Examiner(s): Meky, Moustafa M.
• Application Number:
  US08/852,257
• Time in Patent Office: 1,098 Days
• Field of Search: 709/200, 709/201, 709/203, 709/217, 709/218, 709/219
• US Class Current: 709/203
• CPC Class Codes: H04L 67/00 Network arrangements or protocols for supporting network services or applications user-to-user messaging H04L51/00; network arrangements, protocols or services for supporting real-time applications in data packet communications networks H04L65/00
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

Method, appartus and program products for persistent cache synchronization for communications over an external communication link between a client protocol conversion application executing on a first computer and a server protocol conversion application executing on a second computer located remote from the first computer are provided. Protocol conversion applications are provided on both the host side and the terminal side of the external communication link to provide communications over the external communication link using a differenced communication data stream which includes a reduced volume of data for transmittal. A checkpoint is provided to allow for improved performance on start up of a new communication session over the external communication link between the client application and the server application by initiating a checkpoint request and transmitting the request from the client to the server. The active protocol cache of the server is copied to a checkpoint cache responsive to a received checkpoint request. A checkpoint confirmation message is sent to the client from the server. Responsive to receipt of a checkpoint confirmation message indicating successful copying of the server active protocol cache to a checkpoint cache, the client application creates a checkpoint cache of the first computer as a copy of the protocol cache of the first computer. The first computer creates a checkpoint cache by first creating a temporary cache before initiating the checkpoint and on receipt of a confirmation from the server, converting the temporary cache to a confirmed checkpoint cache.

Claims

1. A method of persistent cache synchronization for communications over an external communication link between an application executing on a first computer and an application executing on a second computer located remote from the first computer, the method comprising the steps of:

establishing a first cache operatively associated with the first computer and a corresponding second cache operatively associated with the second computer wherein the first and second cache are utilized by the applications to improve the performance of communications over the external communication link;

transmitting a checkpoint request to the second computer;

receiving the checkpoint request at the second computer;

copying the second cache responsive to the received checkpoint request to provide a checkpoint cache of the second computer;

transmitting a checkpoint confirmation message to the first computer responsive to said step of copying the second cache;

receiving the checkpoint confirmation message at the first computer;

creating a checkpoint cache of the first computer as a copy of the first cache responsive to the received checkpoint confirmation message to provide a checkpoint; and

then

repeating said steps of transmitting a checkpoint request, receiving the checkpoint request, copying the second cache, transmitting a checkpoint confirmation message, receiving the checkpoint confirmation message, and creating to provide a new checkpoint.

2. A method according to claim 1 wherein said repeating step is preceded by the step of determining if a new checkpoint is desired and wherein said repeating step is executed responsive to said determining step.

3. A method according to claim 2 wherein said determining step comprises the step of determining if a predetermined period has passed since a checkpoint has been taken and wherein said repeating step is executed if the predetermined period has passed.

4. A method according to claim 3 wherein said determining step further comprises the step of determining if an error has occurred in executing said step of copying the second cache and wherein said repeating step is executed responsive to said determining step if an error has occurred.

5. A method according to claim 2 wherein said determining step is performed by the first computer.

6. A method according to claim 1 wherein said step of copying the second cache comprises the steps of:

allocating a checkpoint slot;

copying the second cache to a temporary file;

converting the temporary file to the checkpoint cache of the second computer by associating the temporary file with the allocated checkpoint slot.

7. A method according to claim 6 wherein a plurality of checkpoint slots are associated with the second computer and wherein said step of copying the second cache further comprises the step of:

associating a checkpoint identifier with the checkpoint cache of the second computer; and

wherein said step of converting the temporary cache includes the step of associating the checkpoint cache of the first computer with the checkpoint identifier.

8. A method according to claim 7 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application and wherein said establishing step comprises the steps of:

initiating a communication session by transmitting a request from the client protocol conversion application to the server protocol conversion application over the external communication link;

transmitting the checkpoint identifier of the checkpoint cache of the second computer to the client protocol conversion application;

selecting a checkpoint cache of the first computer corresponding to the checkpoint identifier as the first cache operatively associated with the first computer for use with the initiated communication session;

transmitting an acknowledgment message to the server protocol conversion application acknowledging selection of the checkpoint cache corresponding to the checkpoint identifier as the first cache for use with the initiated communication session responsive to said step of selecting a checkpoint cache of the first computer;

selecting the checkpoint cache of the second computer associated with the checkpoint identifier as the corresponding second cache operatively associated with the second computer for use with the initiated communication session responsive to said transmitting an acknowledgment step.

9. A method according to claim 8 wherein a plurality of checkpoint caches are associated with the second computer and each of the plurality of checkpoint caches has an associated checkpoint identifier and

wherein said step of transmitting the checkpoint identifier comprises the step of transmitting the checkpoint identifier of each of the plurality of checkpoint caches associated with the second computer;

and

wherein said step of selecting the checkpoint cache of the first computer comprises the step of selecting a checkpoint cache of the first computer corresponding to one of the transmitted checkpoint identifiers as the first cache operatively associated with the first computer for use with the initiated communication session; and

wherein said transmitting an acknowledgment step comprises the step of transmitting the checkpoint identifier associated with the selected checkpoint cache of the first computer to the server protocol conversion application; and

wherein said selecting the checkpoint cache of the second computer step comprises the step of selecting the checkpoint cache of the second computer corresponding to the checkpoint identifier transmitted by said transmitting an acknowledgment step as the corresponding second cache operatively associated with the second computer for use with the initiated communication session.

10. A method according to claim 1 wherein said step of transmitting a checkpoint confirmation message comprises the steps of:

determining if the checkpoint cache of the second computer was provided without error by said copying the second cache step; and

transmitting a checkpoint confirmation message indicating a success if no error is indicated by said step of determining if the checkpoint cache of the second computer was provided without error.

11. A method according to claim 10 further comprising the step following said establishing step of:

copying the first cache to a temporary cache of the first computer; and

wherein said step of transmitting a checkpoint confirmation message comprises the step of transmitting a checkpoint confirmation message indicating a failure if an error is indicated by said step of determining if the checkpoint cache of the second computer was provided without error; and

wherein said step of receiving the checkpoint confirmation message comprises the step of determining if the received checkpoint confirmation message indicates a success; and

wherein said creating step comprises the steps of;

converting the temporary cache into a checkpoint cache of the first computer if the received checkpoint confirmation message indicates a success; and

discarding the temporary cache if the received checkpoint confirmation message indicates a failure.

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

initiating a communication session by transmitting a request including an identification of the checkpoint cache of the first computer from the first computer to the second computer over the external communication link;

selecting a checkpoint cache of the second computer corresponding to the transmitted identification as the corresponding second cache operatively associated with the second computer for use with the initiated communication session;

transmitting an acknowledgment message to the first computer acknowledging selection the checkpoint cache of the second computer corresponding to the transmitted identification as the corresponding second cache operatively associated with the second computer for use with the initiated communication session;

selecting the checkpoint cache of the first computer as the first cache operatively associated with the first computer for use with the initiated communication session responsive to said step of transmitting an acknowledgment message.

13. A method according to claim 12 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

14. A method of persistent cache synchronization for a protocol conversion application executing on a second computer and communicating over an external communication link with a protocol conversion application executing on a first computer and located remote from the second computer, the method comprising the steps of:

establishing a protocol cache operatively associated with the second computer wherein the protocol cache is utilized by the protocol conversion application executing on the second computer to improve the performance of communications over the external communication link;

receiving a checkpoint request at the second computer;

copying the protocol cache of the second computer responsive to the received checkpoint request to provide a checkpoint cache of the second computer;

transmitting a checkpoint confirmation message to the first computer responsive to said step of copying the protocol cache of the second computer; and

then

repeating said steps of receiving, copying, and transmitting to provide a new checkpoint cache of the second computer.

15. A method according to claim 14 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

16. A method according to claim 15 wherein said establishing step comprises the steps of:

receiving a request to initiate a communication session from the client protocol conversion application over the external communication link;

transmitting an identification of the checkpoint cache of the second computer to the client protocol conversion application;

receiving an acknowledgment message from the client protocol conversion application acknowledging selection of the identified checkpoint cache for use with the initiated communication session;

selecting the identified checkpoint cache of the second computer as the protocol cache operatively associated with the second computer for use with the initiated communication session.

17. A method of persistent cache synchronization for a protocol conversion application executing on a first computer and communicating over an external communication link with a protocol conversion application executing on a second computer located remote from the first computer, the method comprising the steps of:

establishing a protocol cache operatively associated with the first computer wherein the protocol cache is utilized by the protocol conversion application executing on the first computer to improve the performance of communications over the external communication link;

transmitting a checkpoint request to the second computer;

receiving a checkpoint confirmation message at the first computer;

creating a checkpoint cache of the first computer as a copy of the protocol cache of the first computer responsive to the received checkpoint confirmation message to provide a checkpoint; and

then repeating said steps of transmitting, receiving and creating to provide a new checkpoint.

18. A method according to claim 17 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

19. A method according to claim 18 wherein said establishing step comprises the steps of:

initiating a communication session by transmitting a request from the client protocol conversion application to the server protocol conversion application over the external communication link;

receiving an identification of a checkpoint cache of the second computer from the server protocol conversion application;

selecting a checkpoint cache of the first computer corresponding to the received identification as the protocol cache operatively associated with the first computer for use with the initiated communication session; and

transmitting an acknowledgment message to the server protocol conversion application acknowledging selection of the identified checkpoint cache for use with the initiated communication session.

20. A persistent cache synchronization system for communications over an external communication link between an application executing on a first computer and an application executing on a second computer located remote from the first computer, the method comprising the steps of:

means operatively associated with the first computer for establishing a first cache operatively associated with the first computer;

means operatively associated with the second computer for establishing a corresponding second cache operatively associated with the second computer wherein the first and second cache are utilized by the applications to improve the performance of communications over the external communication link;

means operatively associated with the first computer for determining if a new checkpoint is desired;

means responsive to said determining means for transmitting a checkpoint request to the second computer;

means for receiving the checkpoint request at the second computer;

means for copying the second cache responsive to the received checkpoint request to provide a checkpoint cache of the second computer;

means for transmitting a checkpoint confirmation message to the first computer responsive to said means for copying the second cache;

means for receiving the checkpoint confirmation message at the first computer; and

means for creating a checkpoint cache of the first computer as a copy of the first cache responsive to the received checkpoint confirmation message to provide a checkpoint.

21. A system according to claim 20 wherein said means for determining comprises means for initiating a new checkpoint a predetermined time after a preceding checkpoint is taken.

22. A system according to claim 21 wherein said means for determining further comprises means for determining if the checkpoint cache of the second computer has been provided without error and for initiating a new checkpoint if an error has occurred.

23. A system according to claim 20 wherein said means for copying the second cache comprises:

means for allocating a checkpoint slot;

means for copying the second cache to a temporary file;

means for converting the temporary file to the checkpoint cache of the second computer by associating the temporary file with the allocated checkpoint slot.

24. A system according to claim 23 wherein a plurality of checkpoint slots are associated with the second computer and wherein said means for copying the second cache further comprises:

means for associating a checkpoint identifier with the checkpoint cache of the second computer; and

wherein said means for converting the temporary cache comprises means for associating the checkpoint cache of the first computer with the checkpoint identifier.

25. A system according to claim 24 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application and wherein said means operatively associated with the first computer for establishing comprises:

means for initiating a communication session by transmitting a request from the client protocol conversion application to the server protocol conversion application over the external communication link;

means operatively associated with said client protocol conversion application for receiving a checkpoint identifier of a checkpoint cache of the second computer;

means for selecting a checkpoint cache of the first computer corresponding to the checkpoint identifier as the first cache operatively associated with the first computer for use with the initiated communication session;

means for transmitting an acknowledgment message to the server protocol conversion application acknowledging selection of the checkpoint cache of the first computer corresponding to the checkpoint identifier as the first cache for use with the initiated communication session; and

wherein said means operatively associated with the second computer for establishing comprises;

means for transmitting the checkpoint identifier of a checkpoint cache of the second computer to the client protocol conversion application;

means for receiving an acknowledgment message from the client protocol conversion application acknowledging selection of a checkpoint cache of the first computer corresponding to the checkpoint identifier as the first cache for use with the initiated communication session; and

means responsive to said means for receiving an acknowledgment for selecting a checkpoint cache of the second computer associated with the checkpoint identifier as the corresponding second cache operatively associated with the second computer for use with the initiated communication session.

26. A system according to claim 25 wherein a plurality of checkpoint caches are associated with the second computer and each of the plurality of checkpoint caches has an associated checkpoint identifier and

wherein said means for transmitting the checkpoint identifier comprises means for transmitting the checkpoint identifier of each of the plurality of checkpoint caches associated with the second computer;

and

wherein said means for selecting a checkpoint cache of the first computer comprises means for selecting a checkpoint cache of the first computer corresponding to one of the transmitted checkpoint identifiers as the first cache operatively associated with the first computer for use with the initiated communication session; and

wherein said means for transmitting an acknowledgment comprises means for transmitting the checkpoint identifier associated with the selected checkpoint cache of the first computer to the server protocol conversion application; and

wherein said means for selecting a checkpoint cache of the second computer comprises means for selecting a checkpoint cache of the second computer corresponding to the checkpoint identifier transmitted by said means for transmitting an acknowledgment as the corresponding second cache operatively associated with the second computer for use with the initiated communication session.

27. A system according to claim 20 wherein said means for transmitting a checkpoint confirmation message comprises:

means responsive to said means for copying the second cache for determining if a checkpoint cache of the second computer was provided without error by said means for copying the second cache; and

means for transmitting a checkpoint confirmation message indicating a success if a checkpoint cache of the second computer was provided without error by said means for copying the second cache.

28. A system according to claim 27 further comprising:

means responsive to said determining means for copying the first cache to a temporary cache of the first second computer; and

wherein said means for transmitting a checkpoint confirmation message comprises means for transmitting a checkpoint confirmation message indicating a failure if a checkpoint cache of the second computer was not provided without error by said means for copying the second cache; and

wherein said means for receiving the checkpoint confirmation message comprises means for determining if a received checkpoint confirmation message indicates a success; and

wherein said means for creating comprises;

means for converting the temporary cache into a checkpoint cache of the first computer if the received checkpoint confirmation message indicates a success; and

means for discarding the temporary cache if the received checkpoint confirmation message indicates a failure.

29. A system according to claim 20 wherein said means operatively associated with the first computer for establishing comprises:

means for initiating a communication session by transmitting a request including an identification of the checkpoint cache of the first computer from the first computer to the second computer over the external communication link;

means for receiving an acknowledgment message from the second computer; and

means for selecting the checkpoint cache of the first computer as the first cache operatively associated with the first computer for use with the initiated communication session responsive to said means for receiving an acknowledgment message; and

wherein said means operatively associated with the second computer for establishing comprises;

means operatively associated with the second computer for receiving an identification of the checkpoint cache of the second computer;

means for selecting a checkpoint cache of the second computer corresponding to the transmitted identification as the corresponding second cache operatively associated with the second computer for use with the initiated communication session; and

means for transmitting an acknowledgment message to the first computer acknowledging selection of the checkpoint cache of the second computer corresponding to the transmitted identification as the corresponding second cache operatively associated with the second computer for use with the initiated communication session.

30. A system according to claim 29 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

31. A system of persistent cache synchronization for a protocol conversion application executing on a second computer and communicating over an external communication link with a protocol conversion application executing on a first computer and located remote from the second computer, the system comprising:

means for establishing a protocol cache operatively associated with the second computer wherein the protocol cache is utilized by the protocol conversion application executing on the second computer to improve the performance of communications over the external communication link;

means for receiving a checkpoint request at the second computer;

means responsive to the means for receiving a checkpoint request for copying the protocol cache of the second computer to provide a checkpoint cache of the second computer; and

means responsive to the means for copying the protocol cache of the second computer for transmitting a checkpoint confirmation message to the first computer.

32. A system according to claim 31 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

33. A system according to claim 32 wherein said establishing step comprises the steps of:

means for receiving a request to initiate a communication session from the client protocol conversion application over the external communication link;

means for transmitting an identification of the checkpoint cache of the second computer to the client protocol conversion application;

means for receiving an acknowledgment message from the client protocol conversion application acknowledging selection of the identified checkpoint cache for use with the initiated communication session; and

means for selecting the identified checkpoint cache of the second computer as the protocol cache operatively associated with the second computer for use with the initiated communication session.

34. A system of persistent cache synchronization for a protocol conversion application executing on a first computer and communicating over an external communication link with a protocol conversion application executing on a second computer located remote from the first computer, the system comprising:

means for establishing a protocol cache operatively associated with the first computer wherein the protocol cache is utilized by the protocol conversion application executing on the first computer to improve the performance of communications over the external communication link;

means operatively associated with the first computer for determining if a new checkpoint is desired;

means for transmitting a checkpoint request to the second computer;

means for receiving a checkpoint confirmation message at the first computer; and

means responsive to said means for receiving a checkpoint confirmation message for creating a checkpoint cache of the first computer as a copy of the protocol cache operatively associated with the first computer to provide a checkpoint.

35. A system according to claim 34 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

36. A system according to claim 35 wherein said means for establishing comprises:

means for initiating a communication session by transmitting a request from the client protocol conversion application to the server protocol conversion application over the external communication link;

means for receiving an identification of a checkpoint cache of the second computer from the server protocol conversion application;

means responsive to said means for receiving an identification for selecting a checkpoint cache of the first computer corresponding to the received identification as the protocol cache operatively associated with the first computer for use with the initiated communication session; and

means for transmitting an acknowledgment message to the server protocol conversion application acknowledging selection of the identified checkpoint cache for use with the initiated communication session.

37. A computer program product for persistent cache synchronization for communications over an external communication link between an application executing on a first computer and an application executing on a second computer located remote from the first computer comprising:

A computer-readable storage medium having computer-readable program code means embodied in said medium, said computer-readable program code means comprising;

computer readable program code means operatively associated with the first computer for establishing a first cache operatively associated with the first computer;

computer readable program code means operatively associated with the second computer for establishing a corresponding second cache operatively associated with the second computer wherein the first and second cache are utilized by the applications to improve the performance of communications over the external communication link;

computer readable program code means operatively associated with the first computer for determining if a new checkpoint is desired;

computer readable program code means responsive to said determining computer readable program code means for transmitting a checkpoint request to the second computer;

computer readable program code means for receiving the checkpoint request at the second computer;

computer readable program code means for copying the second cache responsive to the received checkpoint request to provide a checkpoint cache of the second computer;

computer readable program code means for transmitting a checkpoint confirmation message to the first computer responsive to said computer readable program code means for copying the second cache;

computer readable program code means for receiving the checkpoint confirmation message at the first computer; and

computer readable program code means for creating a checkpoint cache of the first computer as a copy of the first cache responsive to the received checkpoint confirmation message to provide a checkpoint.

38. A computer program product according to claim 37 wherein said computer readable program code means for determining comprises computer readable program code means for initiating a new checkpoint a predetermined time after a preceding checkpoint is taken.

39. A computer program product according to claim 38 wherein said computer readable program code means for determining further comprises computer readable program code means for determining if the checkpoint cache of the second computer has been provided without error and for initiating a new checkpoint if an error has occurred.

40. A computer program product according to claim 37 wherein said computer readable program code means for copying the second cache comprises:

computer readable program code means for allocating a checkpoint slot;

computer readable program code means for copying the second cache to a temporary file;

computer readable program code means for converting the temporary file to the checkpoint cache of the second computer by associating the temporary file with the allocated checkpoint slot.

41. A computer program product according to claim 40 wherein a plurality of checkpoint slots are associated with the second computer and wherein said computer readable program code means for copying the second cache further comprises:

computer readable program code means for associating a checkpoint identifier with the checkpoint cache of the second computer; and

wherein said computer readable program code means for converting the temporary cache comprises computer readable program code means for associating the checkpoint cache of the first computer with the checkpoint identifier.

42. A computer program product according to claim 41 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application and wherein said computer readable program code means operatively associated with the first computer for establishing comprises:

computer readable program code means for initiating a communication session by transmitting a request from the client protocol conversion application to the server protocol conversion application over the external communication link;

computer readable program code means operatively associated with said client protocol conversion application for receiving a checkpoint identifier of a checkpoint cache of the second computer;

computer readable program code means for selecting a checkpoint cache of the first computer corresponding to the checkpoint identifier as the first cache operatively associated with the first computer for use with the initiated communication session;

computer readable program code means for transmitting an acknowledgment message to the server protocol conversion application acknowledging selection of the checkpoint cache of the first computer corresponding to the checkpoint identifier as the first cache for use with the initiated communication session; and

wherein said computer readable program code means operatively associated with the second computer for establishing comprises;

computer readable program code means for transmitting the checkpoint identifier of a checkpoint cache of the second computer to the client protocol conversion application;

computer readable program code means for receiving an acknowledgment message from the client protocol conversion application acknowledging selection of a checkpoint cache of the first computer corresponding to the checkpoint identifier as the first cache for use with the initiated communication session; and

computer readable program code means responsive to said computer readable program code means for receiving an acknowledgment for selecting a checkpoint cache of the second computer associated with the checkpoint identifier as the corresponding second cache operatively associated with the second computer for use with the initiated communication session.

43. A computer program product according to claim 42 wherein a plurality of checkpoint caches are associated with the second computer and each of the plurality of checkpoint caches has an associated checkpoint identifier and

wherein said computer readable program code means for transmitting the checkpoint identifier comprises computer readable program code means for transmitting the checkpoint identifier of each of the plurality of checkpoint caches associated with the second computer;

and

wherein said computer readable program code means for selecting a checkpoint cache of the first computer comprises computer readable program code means for selecting a checkpoint cache of the first computer corresponding to one of the transmitted checkpoint identifiers as the first cache operatively associated with the first computer for use with the initiated communication session; and

wherein said computer readable program code means for transmitting an acknowledgment comprises computer readable program code means for transmitting the checkpoint identifier associated with the selected checkpoint cache of the first computer to the server protocol conversion application; and

wherein said computer readable program code means for selecting a checkpoint cache of the second computer comprises computer readable program code means for selecting a checkpoint cache of the second computer corresponding to the checkpoint identifier transmitted by said computer readable program code means for transmitting an acknowledgment as the corresponding second cache operatively associated with the second computer for use with the initiated communication session.

44. A computer program product according to claim 37 wherein said computer readable program code means for transmitting a checkpoint confirmation message comprises:

computer readable program code means responsive to said computer readable program code means for copying the second cache for determining if a checkpoint cache of the second computer was provided without error by said computer readable program code means for copying the second cache; and

computer readable program code means for transmitting a checkpoint confirmation message indicating a success if a checkpoint cache of the second computer was provided without error by said computer readable program code means for copying the second cache.

45. A computer program product according to claim 44 further comprising:

computer readable program code means responsive to said computer readable program code means for determining for copying the first cache to a temporary cache of the first second computer; and

wherein said computer readable program code means for transmitting a checkpoint confirmation message comprises computer readable program code means for transmitting a checkpoint confirmation message indicating a failure if a checkpoint cache of the second computer was not provided without error by said computer readable program code means for copying the second cache; and

wherein said computer readable program code means for receiving the checkpoint confirmation message comprises computer readable program code means for determining if a received checkpoint confirmation message indicates a success; and

wherein said computer readable program code means for creating comprises;

computer readable program code means for converting the temporary cache into a checkpoint cache of the first computer if the received checkpoint confirmation message indicates a success; and

computer readable program code means for discarding the temporary cache if the received checkpoint confirmation message indicates a failure.

46. A computer program product according to claim 37 wherein said computer readable program code means operatively associated with the first computer for establishing comprises:

computer readable program code means for initiating a communication session by transmitting a request including an identification of the checkpoint cache of the first computer from the first computer to the second computer over the external communication link;

computer readable program code means for receiving an acknowledgment message from the second computer; and

computer readable program code means for selecting the checkpoint cache of the first computer as the first cache operatively associated with the first computer for use with the initiated communication session responsive to said computer readable program code means for receiving an acknowledgment message; and

wherein said computer readable program code means operatively associated with the second computer for establishing comprises;

computer readable program code means operatively associated with the second computer for receiving an identification of the checkpoint cache of the second computer;

computer readable program code means for selecting a checkpoint cache of the second computer corresponding to the transmitted identification as the corresponding second cache operatively associated with the second computer for use with the initiated communication session; and

computer readable program code means for transmitting an acknowledgment message to the first computer acknowledging selection of the checkpoint cache of the second computer corresponding to the transmitted identification as the corresponding second cache operatively associated with the second computer for use with the initiated communication session.

47. A computer program product according to claim 46 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

48. A computer program product for persistent cache synchronization for a protocol conversion application executing on a second computer and communicating over an external communication link with a protocol conversion application executing on a first computer and located remote from the second computer, the computer program product comprising:

A computer-readable storage medium having computer-readable program code means embodied in said medium, said computer-readable program code means comprising;

computer readable program code means for establishing a protocol cache operatively associated with the second computer wherein the protocol cache is utilized by the protocol conversion application executing on the second computer to improve the performance of communications over the external communication link;

computer readable program code means for receiving a checkpoint request at the second computer;

computer readable program code means responsive to the computer readable program code means for receiving a checkpoint request for copying the protocol cache of the second computer to provide a checkpoint cache of the second computer; and

computer readable program code means responsive to the computer readable program code means for copying the protocol cache of the second computer for transmitting a checkpoint confirmation message to the first computer.

49. A computer program product according to claim 48 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

50. A computer program product according to claim 49 wherein said establishing step comprises the steps of:

computer readable program code means for receiving a request to initiate a communication session from the client protocol conversion application over the external communication link;

computer readable program code means for transmitting an identification of the checkpoint cache of the second computer to the client protocol conversion application;

computer readable program code means for receiving an acknowledgment message from the client protocol conversion application acknowledging selection of the identified checkpoint cache for use with the initiated communication session; and

computer readable program code means for selecting the identified checkpoint cache of the second computer as the protocol cache operatively associated with the second computer for use with the initiated communication session.

51. A computer program product for persistent cache synchronization for a protocol conversion application executing on a first computer and communicating over an external communication link with a protocol conversion application executing on a second computer located remote from the first computer, the computer program product comprising:

A computer-readable storage medium having computer-readable program code means embodied in said medium, said computer-readable program code means comprising;

computer readable program code means for establishing a protocol cache operatively associated with the first computer wherein the protocol cache is utilized by the protocol conversion application executing on the first computer to improve the performance of communications over the external communication link;

computer readable program code means operatively associated with the first computer for determining if a new checkpoint is desired;

computer readable program code means for transmitting a checkpoint request to the second computer;

computer readable program code means for receiving a checkpoint confirmation message at the first computer; and

computer readable program code means responsive to said computer readable program code means for receiving a checkpoint confirmation message for creating a checkpoint cache of the first computer as a copy of the protocol cache operatively associated with the first computer to provide a checkpoint.

52. A computer program product according to claim 51 wherein the application executing on the first computer is a client protocol conversion application and the application executing on the second computer is a server protocol conversion application.

53. A computer program product according to claim 52 wherein said computer readable program code means for establishing comprises:

computer readable program code means for initiating a communication session by transmitting a request from the client protocol conversion application to the server protocol conversion application over the external communication link;

computer readable program code means for receiving an identification of a checkpoint cache of the second computer from the server protocol conversion application;

computer readable program code means responsive to said computer readable program code means for receiving an identification for selecting a checkpoint cache of the first computer corresponding to the received identification as the protocol cache operatively associated with the first computer for use with the initiated communication session; and

computer readable program code means for transmitting an acknowledgment message to the server protocol conversion application acknowledging selection of the identified checkpoint cache for use with the initiated communication session.