System and method for data synchronization

• US 7,721,002 B2
• Filed: 06/29/2006
• Issued: 05/18/2010
• 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): Meky; Moustafa M
• Assistant Examiner(s): Burgess; Barbara N
• Application Number:
  US11/427,690
• Publication Number:
  US 20060242327A1
• Time in Patent Office: 1,419 Days
• Field of Search: 709/208, 709/209, 709/203, 709/248, 709/211, 709/214, 709/215, 711/119, 711/120, 711/121, 711/123, 711/124, 711/137
• 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 initialized, 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, by a web server of the plurality of web servers, a scheduled activation time from the common data server;

Prior to the scheduled activation time, receiving the scheduled update data, the scheduled update data including data prospectively to be employed by the plurality of web servers in processing transactions, into the 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;

Wherein each web server of the plurality of web servers is further configured to adjust a scheduled activation time on the web server by a time difference between a clock in the web server and a clock in the common data server.

2. A method as recited in claim 1 wherein each web server contains a clock, and wherein the clocks in 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 data 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 retrieving scheduled update data into staging caches in the plurality of web servers is performed asynchronously.

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

12. A system comprising:

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

a staging cache;

an active data cache coupled to the staging cache;

wherein the web server of the plurality of web servers is configured to receive a scheduled activation time from the common data server, and further configured to receive scheduled update data, the scheduled update data including data prospectively to be employed by the plurality of web servers in processing transactions, from the common data server into the staging cache prior to the scheduled activation time; and

wherein the web server of the plurality of web servers 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;

wherein each web server of the plurality of web servers is further configured to adjust a scheduled activation time on the web server by a time difference between a clock in the web server and a clock in the common data server.

13. A system as recited in claim 12 wherein each web server contains a clock, and wherein the clocks in the plurality of web servers are not synchronized with one another.

14. A system as recited in claim 12 wherein the web server is further configured to swap an active data cache pointer with a staged data cache pointer.

15. A system as recited in claim 12 wherein each of the plurality of web servers is configured to update data caches in the common data server after the scheduled activation time.

16. A system as recited in claim 12 wherein each of the plurality of web servers is configured to calculate a next scheduled activation time after the scheduled activation time.

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

Receiving, by a web server of the plurality of web servers, a scheduled activation time from the common data server;

Prior to the scheduled activation time, receiving scheduled update data into a staging cache in the web server, the scheduled update data including data prospectively to be employed by the plurality of web servers in processing transactions;

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;

After the scheduled activation time, updating data caches in the common data server and calculating a next scheduled activation time;

Wherein the web server of the plurality of web servers is further configured to adjust a scheduled activation time on the web server by a time difference between a clock in the web server and a clock in the common data server.

18. One or more computer-readable media as recited in claim 17 wherein each server contains a clock, and wherein the clocks in the plurality of servers are not synchronized with one another.

19. One or more computer-readable media as recited in claim 17 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.