System and method for data synchronization

• US 7,181,539 B1
• Filed: 09/01/1999
• Issued: 02/20/2007
• Est. Priority Date: 09/01/1999
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Messner, David J., Knight, Kenneth J.
• Primary Examiner(s): Etienne; Ario
• Assistant Examiner(s): BURGESS, BARBARA N
• Application Number:
  US09/388,829
• Time in Patent Office: 2,729 Days
• Field of Search: 709/248, 709208-209, 709/203, 711/133, 711/137, 711119-124
• US Class Current: 709/248
• CPC Class Codes: G06F 16/958 Organisation or management of web site content, e.g. publishing, maintaining pages or automatic linking

Abstract

Data is synchronized among multiple web servers, each of which is coupled to a common data server. Each web server retrieves a scheduled activation time from the data server. If the current time is prior to the scheduled activation time, then each web server retrieves updated data from the data server into a staging cache in the web server. At the scheduled activation time, each web server copies data from its staging cache to an active cache in the web server. If a new web server is added or an existing web server is initiated, then data is copied from an active cache in the data server to an active cache in the new or initialized web server. The multiple web servers may be arranged to form a web farm.

Claims

1. A method of synchronizing activation of scheduled update data among a plurality of web servers, wherein each of the plurality of web servers is coupled to a common data server, the method comprising:

receiving a scheduled activation time from the common data server;

comparing a time associated with a clock in each web server of the plurality of web servers to a time associated with a clock in the common data server;

adjusting the scheduled activation time on each web server of the plurality of web servers by the time difference between the clock in each web server of the plurality of web servers and the click in the common data server;

prior to the scheduled activation time, receiving the scheduled update data into staging caches in each web server of the plurality of web servers; and

at the scheduled activation time, activating the scheduled update data by causing the scheduled update data from the staging caches within each web server of the plurality of web servers to be accessible from an active cache within each web server of the plurality of web servers.

2. A method as recited in claim 1 wherein each web server of the plurality of web servers contains a clock, and wherein the clocks in each web server of the plurality of web servers are not synchronized with one another.

3. A method as recited in claim 1 wherein the causing the scheduled update to be accessible from the active cache comprises swapping an active data cache pointer with a staged data cache pointer.

4. A method as recited in claim 1 wherein no communications are required between the individual web servers to synchronize their data.

5. A method as recited in claim 1 wherein the receiving scheduled update data into staging caches in each web server of the plurality of web servers is performed asynchronously.

6. A method as recited in claim 1 further comprising:

after the scheduled activation time, updating data caches in the common data server.

7. A method as recited in claim 1 further comprising:

after the scheduled activation time, calculating a next scheduled activation time.

8. A method as recited in claim 1 further comprising:

after the scheduled activation time, updating data caches in the common data server and calculating a next scheduled activation time, wherein the updating and calculating are performed by the first web server to initiate a retrieval process after the scheduled activation time.

9. A method as recited in claim 1 further comprising:

if an additional web server is coupled to the common data server, then causing the scheduled update data to be accessible from the active cache in the common data server to an active cache in the additional web server.

10. A method as recited in claim 1 further comprising:

if one of the plurality of web servers of the plurality of web servers is initialized, then causing the scheduled update data to be accessible from the active cache in the common data server to the active cache in the initialized web server.

11. A method as recited in claim 1 wherein the plurality of web servers comprise a web farm.

12. A method as recited in claim 1 wherein the plurality of web servers comprise a web farm, and wherein the plurality of web servers are load balanced using a domain name service (DNS) round-robin technique.

13. One or more computer-readable memories containing a computer program that is executable by a processor to perform the method recited in claim 1.

14. A system comprising:

a web server of a plurality of web servers coupled to a common data server, wherein the web server of the plurality of web servers comprises;

a staging cache;

an active data cache coupled to the staging cache; and

a clock having an associated time,

wherein the web server is configured to receive a scheduled activation time from the common data server, and further configured to receive scheduled update data from the common data server into the staging cache prior to the scheduled activation time;

wherein the web server is configured to compare the time associated with the clock in the web server to a time associated with a clock in the common data server;

wherein the web server is further configured to adjust the scheduled activation time on the web server by the time difference between the clock in the web server and the clock in the common data server; and

wherein the web server is configured to cause the scheduled update data from the staging cache to be accessible from the active data cache at the scheduled activation time.

15. A system as recited in claim 14 wherein the web server of the plurality of web servers contains a clock, and wherein the clock in the web server of the plurality of web servers is not synchronized with other web servers of the plurality of web servers.

16. A system as recited in claim 14 wherein the web server is further configured to swap an active data cache pointer with a staged data cache pointer.

17. A system as recited in claim 14 wherein the web server of the plurality of web servers is configured to update data caches in the common data server after the scheduled activation time.

18. A system as recited in claim 14 wherein the web server of the plurality of web servers is configured to calculate a next scheduled activation time after the scheduled activation time.

19. A system as recited in claim 14 wherein the plurality of web servers comprise a web farm.

20. One or more computer-readable media having stored thereon a computer program that when executed performs a method comprising the following steps:

receiving a scheduled activation time from a common data server;

prior to the scheduled activation time, receiving scheduled update data into a staging cache in a web server;

comparing a time associated with a clock in the web server to a time associated with a clock in the common data server;

adjusting the scheduled activation time on the web server by the time difference between the clock in the web server and the clock in the common data server;

at the scheduled activation time, causing scheduled update data from the staging cache in the web server to be accessible from an active cache in the web server; and

after the scheduled activation time, updating data caches in the common data server and calculating a next scheduled activation time.

21. One or more computer-readable media as recited in claim 20 wherein the web server of a plurality of web servers contains a clock, and wherein the click in the web server of the plurality of web servers is not synchronized with other web servers of the plurality of web servers.

22. One or more computer-readable media as recited in claim 20 wherein updating data caches in the common data server and calculating the next scheduled activation time are performed if another process has not yet updated the data caches or calculated the next scheduled activation time during a current data synchronization cycle.

23. One or more computer-readable media as recited in claim 20 further comprising:

if the web server is initialized, then causing the scheduled update data to be accessible from the active cache in the common data server to the active cache in the initialized web server.

24. One or more computer-readable media as recited in claim 20 wherein the causing the scheduled update data to be accessible from the active cache comprises swapping an active data cache pointer with a staged data cache pointer.

25. A method of synchronizing activation of scheduled update data among each web server of a plurality of web servers, wherein each web server of the plurality of web servers is coupled to a common data server, the method comprising:

providing a scheduled activation time from the common data server to each web server of the plurality of web servers;

communicating the scheduled update data into a staging cache in each web server of the plurality of web servers prior to the scheduled activation time;

comparing a time recognized by each web server of the plurality of web servers to a current time recognized by the common data server;

adjusting the scheduled activation time on each web server of the plurality of web servers by the time difference between the time recognized by each web server of the plurality of web servers and the current time recognized by the common data server; and

causing the scheduled update data from the staging cache in each web server of the plurality of the web servers to be accessible from an active cache in each web server of the plurality of the web servers at the scheduled activation time.

26. A method as recited in claim 25 wherein the communicating scheduled update data into a staging cache is performed asynchronously.

27. A method as recited in claim 25 wherein the causing the scheduled update data to be accessible from the active cache comprises swapping an active data cache pointer with a staged data cache pointer.

28. A method as recited in claim 25 wherein no communication is required between each web server of the plurality of web servers to synchronize their data.

29. One or more computer-readable memories containing a computer program that is executable by a processor to perform the method recited in claim 25.