Methodology for cache coherency of web server data

• US 6,219,676 B1
• Filed: 08/06/1999
• Issued: 04/17/2001
• Est. Priority Date: 03/29/1999
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Novell Incorporated (Open Text Corporation)
• Inventors: Reiner, Paul
• Primary Examiner(s): Burgess, Glenton B.
• Assistant Examiner(s): EDELMAN, BRADLEY E
• Application Number:
  US09/369,947
• Time in Patent Office: 620 Days
• Field of Search: 711/141, 711/144, 711/145, 707/201, 707/203, 709/201, 709/219, 709/224
• US Class Current: 1/1
• CPC Class Codes: H04L 67/5682 Policies or rules for updating, deleting or replacing the stored data
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A method and system to establish and maintain cache coherency between a web server and one or more clients communicating through a network. The method includes designating monitor areas on a data segment of the server, determining if an activity occurs in one of the monitor areas, updating a change log if such activity occurs, and indicating the updated status of the change log to the clients. The method also handles requests from the clients and responding to those requests. Clients can then check the change log for updates, instead of resorting to dredging or web crawling.

Claims

1. A method for allowing a web server to maintain coherency of web server data with a plurality of clients, the web server data comprising a plurality of web pages, each web page comprising a plurality of objects, the method comprising the steps of:

defining at least one monitor area for the web server data;

detecting at least one activity that occurs in the monitor area, the activity being a change to a web page;

storing a reference value for the activity in at least one version of a change log at the web server, the change log being of a relatively small size, as compared to the monitor area, and the reference value indicating an object of the web page that has been changed by the activity;

indicating a time when the reference value was stored in the change log, the time being accessible by a client for determining whether to retrieve the object identified by the reference value; and

providing the reference value to the client when the client accesses the web server, if the client so determines, thereby maintaining coherency with the web server,

wherein the change log is separate from the web server data and the tracked activity is immediately provided to the client without accessing the web server data.

2. The method of claim 1 further comprising the step of requesting notification of an activity in the defined monitor areas.

3. The method of claim 1 further comprising the step of indicating the updated status of the change log by a flag to the client, so that the client can know that the change log has been updated by checking the flag.

4. The method of claim 1 wherein the reference value is a uniform resource locator.

5. A web server comprising:

a processor for running operating code;

a storage unit for storing a data segment having at least one monitor area and at least one version of a change log of a smaller size than the monitor area, the monitor area including a plurality of web pages each web page, referencing a plurality of objects;

an interface to a client computer; and

a plurality of stored instructions, including;

an instruction for determining if an activity occurs to a web page in the monitor area;

an instruction for updating the change log if the activity occurs by providing a reference to an object to which the activity occurred;

an instruction for indicating the updated status of the change log to the client computer upon receipt of a request by the client computer, the updated status including a time that the change log was updated with the reference;

an instruction for receiving the request from the client computer; and

an instruction for responding to the request by providing the reference to the client computer so that the client computer can update an internal value for the object.

6. The web server of claim 5 wherein the instruction for indicating the updated status of the change log to the client utilizes a flag.

7. A computer program stored on a computer readable media comprising instructions for:

identifying a data monitor area, the data monitor area including at least one web page comprising a plurality of objects;

maintaining at least one version of a change log of a predetermined workable size for tracking changes to objects of the web page on an object-by-object basis by listing a reference to the object;

receiving a request to update a client; and

indicating the updated status of the change log to the client by allowing the client to access the change log, so that the client can be notified of the tracked changes to the objects through the change log,

wherein the change log is separate from the data monitor area and the reference to the object is identifiable in the change log by the client without searching the data monitor area.

8. The computer program of claim 7 further comprising instructions for:

determining if a first time period has expired, and

if a first time period has expired, creating a new version of the change log, the new version of the change low residing with the prior version of the change low at the web server,

wherein the instructions for storing includes identifying a latest version of the change log for receiving the reference value.

9. The computer program of claim 8 further comprising instructions for determining if a second time period has expired, and if so, consolidating any prior versions of the change log.

10. The program of claim 9 wherein the change log is consolidated by combining all previous change logs.

11. The computer program of claim 7 wherein the instruction for indicating the updated status of the change log utilizes a flag.

12. The program of claim 7 wherein the instructions for maintaining further includes:

determining when an activity occurs in the data monitor area; and

updating the change log in response to the activity occurred.