Methods, systems and computer program products for the synchronization of time coherent caching system

• US 5,878,213 A
• Filed: 02/15/1996
• Issued: 03/02/1999
• Est. Priority Date: 02/15/1996
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Lindquist, David Bruce, Fraenkel, Michael Levi, Housel, Barron Cornelius III, Bittinger, Reed Richard
• Primary Examiner(s): Robertson, David L.
• Application Number:
  US08/601,753
• Time in Patent Office: 1,111 Days
• Field of Search: 395/427, 395/200.43, 395/200.33
• US Class Current: 709/203
• CPC Class Codes: G06F 16/10 File systems; File servers

Abstract

A method, apparatus and computer program product for caching data received from a first application and to be provided to a second application in response to a request from the second application. The method apparatus and computer program products including storing a data stream to be received from the first application and to be provided to the second application in a cache to create a client cache entry corresponding to the request from the second application. The time of creation of a client cache entry is also stored to create a client cache entry time record. Requests from the second application are interrogated to determine if a client cache entry exists corresponding to the request. The client cache entry time record for the client cache entry corresponding to the request from the second application is evaluated to determine if the client cache entry corresponding to the request from the second application was created within a predetermined client coherency time interval prior to the second application requesting the information. The client cache entry is supplied to the second application in response to the request if a client cache entry for the request from the second application was created within a predetermined client coherency time interval prior to the second application requesting the information.

Claims

1. A method of caching data received from a first application and to be provided to a second application in response to a request from the second application, the method comprising:

storing a data stream to be received from the first application and to be provided to the second application in a first cache to create a client cache entry corresponding to the request from the second application;

storing the time of creation of a client cache entry to create a client cache entry time record;

storing the data stream from the first application in response to a request from the second application in a second cache to create a server request cache entry;

interrogating requests originated by the second application and received by the first application to determine if a server request cache entry corresponding to the request has been previously stored in the second cache;

determining if a client cache entry exists corresponding to a request from the second application which is identical to a server cache entry corresponding to the request;

calculating the interval of time between receipt of the request the request from the second application and when the server request cache entry corresponding to the request from the second application was created to provide entry age data if the client cache entry is identical to the server cache entry;

sending the server request cache entry corresponding to the request from the second application to the second application if the client cache entry is not identical to the server cache entry; and

transmitting the entry age data for the server cache entry corresponding to the request from the second application to the second application if the server cache entry is identical to the client cache entry.

2. A method according to claim 1 further comprising the step of maintaining client cache entries across multiple instances of the second application.

3. The method of claim 1 further comprising the steps of:

interrogating requests from the second application to determine if a client cache entry exists corresponding to the request;

evaluating the client cache entry time record for the client cache entry corresponding to the request from the second application to determine if the client cache entry corresponding to the request from the second application was created within a predetermined client coherency time interval prior to the second application requesting the information;

supplying the client cache entry to the second application in response to the request if said evaluating step determines that a client cache entry for the request from the second application was created within a predetermined client coherency time interval prior to the second application requesting the information.

4. The method of claim 1 further comprising the steps of:

determining if a server request cache entry corresponding to the request from the second application was created within a predetermined client coherency time interval prior to the first application receiving the request; and

wherein said sending step comprises sending the server request cache entry which corresponds to the request from the second application if said determining step determines that the server request cache entry was created within the predetermined client coherency time interval.

5. The method according to claim 1 further comprising the step of:

updating the client cache entry time record corresponding to the request from the second application by subtracting from the current time of the second computer the entry age data received from the first computer.

6. The method of claim 1 wherein the second application is a web browser and the first application is a web server.

7. The method of claim 1 wherein the first application is a web server, the second application is a web browser and wherein the first and second applications communicate over a wireless communication link.

8. An apparatus for caching data received from a first application and to be provided to a second application in response to a request from the second application, the apparatus comprising:

means for storing a data stream to be received from the first application and to be provided to the second application in a first cache to create a client cache entry corresponding to the request from the second application;

means for storing the time of creation of a client cache entry to create a client cache entry time record;

means for storing the data stream from the first application in response to a request from the second application in a second cache to create a server request cache entry;

means for interrogating requests originated by the second application to determine if a server request cache entry corresponding to the request has been previously stored in the second cache;

means for determining if a client cache entry exists corresponding to a request from the second application which is identical to a server cache entry corresponding to the request;

means for calculating the interval of time between when the first application received the request from the second application and when the server request cache entry corresponding to the request from the second application was created to provide entry age data if the client cache entry is identical to the server cache entry;

means for sending the server request cache entry corresponding to the request from the second application to the second application if the client cache entry is not identical to the server cache entry; and

means for transmitting the entry age data for the server cache entry corresponding to the request from the second application to the second application if the server cache entry is identical to the client cache entry.

9. An apparatus according to claim 8 further comprising means for maintaining client cache entries across multiple instances of the second application.

10. The apparatus of claim 8 further comprising:

means for interrogating requests from the second application to determine if a client cache entry exists corresponding to the request;

means for evaluating the client cache entry time record for the client cache entry corresponding to the request from the second application to determine if the client cache entry corresponding to the request from the second application was created within a predetermined client coherency time interval prior to the second application requesting the information;

means for supplying the client cache entry to the second application in response to the request if said evaluating step determines that a client cache entry for the request from the second application was created within a predetermined client coherency time interval prior to the second application requesting the information.

11. The apparatus of claim 8 further comprising:

means for determining if a server request cache entry corresponding to the request from the second application was created within a predetermined client coherency time interval prior to the first application receiving the request; and

wherein said means for sending comprises means for sending the server request cache entry which corresponds to the request from the second application if said means for determining determines that the server request cache entry was created within the predetermined client coherency time interval.

12. The apparatus according to claim 8 further comprising:

means for updating the client cache entry time record corresponding to the request from the second application by subtracting from the current time of the second computer the received entry age data.

13. The apparatus of claim 8 wherein the second application is a web browser and the first application is a web server.

14. The apparatus of claim 8 wherein the first application is a web server, the second application is a web browser and wherein the first and second applications communicate over a wireless communication link.

15. A computer program product for caching data received from a first application and to be provided to a second application in response to a request from the second application, 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 storing a data stream to be received from the first application and to be provided to the second application in a first cache to create a client cache entry corresponding to the request from the second application;

computer readable program code means for storing the time of creation of a client cache entry to create a client cache entry time record;

computer readable program means for storing the data stream from the first application in response to a request from the second application in a second cache to create a server request cache entry;

computer readable program code means for interrogating requests originated by the second application to determine if a server request cache entry corresponding to the request has been previously stored in the second cache;

computer readable program code means for determining if a client cache entry exists corresponding to a request from the second application which is identical to a server cache entry corresponding to the request;

computer readable program code means for calculating the interval of time between when the first application received the request from the second application and when the server request cache entry corresponding to the request from the second application was created to provide entry age data if the client cache entry is identical to the server cache entry;

computer readable program code means for sending the server request cache entry corresponding to the request from the second application to the second application if the client cache entry is not identical to the server cache entry; and

computer readable program code means for transmitting the entry age data for the server cache entry corresponding to the request from the second application to the second application if the serve cache entry is identical to the client cache entry.

16. The computer program product according to claim 15 further comprising computer readable program code means for maintaining client cache entries across multiple instances of the second application.

17. The computer program product of claim 15 further comprising:

computer readable program code means for interrogating requests from the second application to determine if a client cache entry exists corresponding to the request;

computer readable program code means for evaluating the client cache entry time record for the client cache entry corresponding to the request from the second application to determine if the client cache entry corresponding to the request from the second application was created within a predetermined client coherency time interval prior to the second application requesting the information;

computer readable program code means for supplying the client cache entry to the second application in response to the request if said evaluating step determines that a client cache entry for the request from the second application was created within a predetermined client coherency time interval prior to the second application requesting the information.

18. The computer program product of claim 15 further comprising:

computer readable program code means for determining if a server request cache entry corresponding to the request from the second application was created within a predetermined client coherency time interval prior to the first application receiving the request; and

wherein said computer readable program code means for sending comprises computer readable program code means for sending the server request cache entry which corresponds to the request from the second application if said computer readable program code means for determining determines that the server request cache entry was created within the predetermined client coherency time interval.

19. The computer program product according to claim 15 further comprising:

computer readable program code means for updating the client cache entry time record corresponding to the request from the second application by subtracting from the current time of the second computer the entry age data received from the first computer.

20. The computer program product of claim 15 wherein the second application is a web browser and the first application is a web server.

21. The computer program product of claim 15 wherein the first application is a web server, the second application is a web browser and wherein the first and second applications communicate over a wireless communication link.