Method and system for migrating object update messages through synchronous data propagation

• US 8,713,098 B1
• Filed: 09/30/2011
• Issued: 04/29/2014
• Est. Priority Date: 10/01/2010
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Adya, Atul, Cooper, Gregory H., Myers, Daniel Sumers, Ghosh, Arunabha
• Primary Examiner(s): Etienne, Ario
• Assistant Examiner(s): SHIU, HO T
• Application Number:
  US13/251,000
• Time in Patent Office: 942 Days
• Field of Search: None
• US Class Current: 709/203
• CPC Class Codes: H04L 63/0807 using tickets, e.g. Kerberos cryptographic mechanisms or cryptographic arrangements for entity authentication using tickets or tokens H04L9/3213
• CPC Class Codes: H04L 67/1004 Server selection for load balancing
• CPC Class Codes: H04L 67/148 Migration or transfer of sessions
• CPC Class Codes: H04L 67/5683 Storage of data provided by user terminals, i.e. reverse caching

Abstract

A computer-implemented method in a distributed network system is disclosed. The computer-implemented method includes: receiving, at a server, a first object update message from a server-side application, wherein the first object update message includes a first object identifier; identifying, among a plurality of object-client registration records, an object-client registration record that includes the first object identifier; updating the object-client registration record in accordance with the first object update message; selecting a set of client identifiers associated with the first object identifier from the object-client registration record; and, for a first client identifier in the selected set of client identifiers, sending a second object update message to a first client device associated with the first client identifier, wherein the second object update message includes the first object identifier.

Claims

1. A computer-implemented method, comprising:

at a server having memory and one or more processors, managing objects for a web-based application hosted by one or more application servers, including;

receiving an object registration message from a first client device, the object registration message including;

a first client identifier corresponding to the first client device; and

a first object identifier corresponding to a first object cached at the first client device, wherein the first object is used by the web-based application;

updating an object-client registration table using the first client identifier and the first object identifier, thereby registering the first client device to receive notifications of updates to the first object;

receiving a first object update message that includes the first object identifier and a first object version number, wherein the first object update message corresponds to an update to the first object at a second client device while using the web-based application;

updating the object-client registration table to specify the first object version number as a current version of the first object;

and

in accordance with the registration of the first client device to receive notifications of updates to the first object, sending a second object update message to the first client device, wherein the second object update message includes the first object identifier and the first object version number;

wherein a last object update timestamp is stored when the first object update message is received, and the last object update timestamp is cleared upon receiving acknowledgement that object updates corresponding to the first object update message have been propagated, thereby assuring that the object updates are propagated even when the server has a failure.

2. The method of claim 1, wherein the object registration message includes a second object version number corresponding to the first object cached at the first client device, the method further comprising sending a third object update message to the first client device when the second object version number is less than the object'"'"'s version number in the object-client registration table.

3. The method of claim 1, further comprising:

receiving an object deregistration message from the first client device, wherein the object deregistration message includes the first object identifier and the first client identifier; and

updating the object-client registration table in accordance with the object deregistration message, thereby preventing the server from sending subsequent object update messages for the first object to the first client device.

4. The method of claim 1, further comprising:

after updating the object-client registration table, sending a first object update confirmation message to the sender of the first object update message.

5. The method of claim 1, further comprising:

receiving a fourth object update message that includes the first object identifier and a third version number of the first object;

when the third version number is less than or equal to the object'"'"'s version number in the object-client registration table, not updating the object-client registration table in response to the fourth object-update message; and

when the third version number is greater than the object'"'"'s version number in the object-client registration table;

updating the object-client registration table to specify the third version number as the current version of the first object; and

updating the stored last object update timestamp according to the fourth object update message, regardless of whether a most recently stored last object update timestamp has been cleared.

6. The method of claim 1, further comprising after updating the object-client registration table to specify the first object version number as the current version of the first object:

utilizing a client notification table to specify each of the client devices to update with the first object version of the first object, the client notification table including a separate record for each client device registered to receive updates to the first object, including a record that specifies the first client identifier and the first object identifier;

receiving a second object confirmation message from the first client device in response to sending the second object update message to the first client device; and

updating the client notification table accordingly, thereby assuring that the first client device is notified of the first object version of the first object.

7. The method of claim 1, further comprising:

when no second object update confirmation message is received from the first client device within a predefined span of time, resending the second object update message to the first client device.

8. The method of claim 1, wherein the second object update message includes a copy of the first object corresponding to the first object version number.

9. The method of claim 1, wherein the second object update message does not include a copy of the first object corresponding to the first object version number, prompting the first client device to retrieve the first object corresponding to the first object version number from the one or more application servers.

10. The method of claim 1, further comprising when no second object update confirmation message is received from the first client device within a predefined number of attempts:

updating the object-client registration table to remove references to the first client identifier, thereby preventing the server from sending any further object update messages to the first client device.

11. The method of claim 1, wherein the last object update timestamp is included in the first object update message.

12. The method of claim 1, wherein the last object update timestamp is specified according to when the first object update message is received.

13. The method of claim 1, wherein the last object update timestamp is stored in the registration table.

14. The method of claim 1, wherein the last object update timestamp is specified according to a monotonically increasing function of time.

15. The method of claim 1, further comprising:

determining based on the last object update timestamp that a predetermined amount of time has passed without receiving acknowledgement that object updates corresponding to the first object update message have been propagated; and

repropagating the updates corresponding to the first object update message.

16. A server system for managing objects for a web-based application hosted by one or more application servers, comprising:

one or more processors for executing programs; and

memory storing data and one or more programs executable by the one or more processors, the one or more programs including instructions for;

receiving an object registration message from a first client device, the object registration message including;

a first client identifier corresponding to the first client device; and

a first object identifier corresponding to a first object cached at the first client device, wherein the first object is used by the web-based application;

updating an object-client registration table using the first client identifier and the first object identifier, thereby registering the first client device to receive notifications of updates to the first object;

receiving a first object update message that includes the first object identifier and a first object version number, wherein the first object update message corresponds to an update to the first object at a second client device while using the web-based application;

updating the object-client registration table to specify the first object version number as a current version of the first object;

and

in accordance with the registration of the first client device to receive notifications of updates to the first object, sending a second object update message to the first client device, wherein the second object update message includes the first object identifier and the first object version number;

wherein a last object update timestamp is stored when the first object update message is received, and the last object update timestamp is cleared upon receiving acknowledgement that object updates corresponding to the first object update message have been propagated, thereby assuring that the object updates are propagated even when the server system has a failure.

17. The server system of claim 16, wherein the first object registration message includes a second object version number corresponding to the first object cached at the first client device, the one or more programs further comprising instructions for sending a third object update message to the first client device when the second object version number is less than the object'"'"'s version number in the object-client registration table.

18. The server system of claim 16, wherein the one or more programs include instructions for:

receiving an object deregistration message from the first client device, wherein the object deregistration message includes the first object identifier and the first client identifier; and

updating the object-client registration table in accordance with the object deregistration message, thereby preventing the server from sending subsequent object update messages for the first object to the first client device.

19. The server system of claim 16, wherein the one or more programs include instructions for:

receiving a fourth object update message that includes the first object identifier and a third version number of the first object;

when the third version number is less than or equal to the object'"'"'s version number in the object-client registration table, not updating the object-client registration table in response to the fourth object-update message; and

when the third version number is greater than the object'"'"'s version number in the object-client registration table;

updating the object-client registration table to specify the third version number as the current version of the first object; and

updating the stored last object update timestamp according to the fourth object update message, regardless of whether a most recently stored last object update timestamp has been cleared.

20. The server system of claim 16, wherein the one or more programs further include instructions that execute after updating the object-client registration table to specify the first object version number as the current version of the first object, the instructions for:

utilizing a client notification table to specify each of the client devices to update with the first object version of the first object, the client notification table including a separate record for each client device registered to receive updates to the first object, including a record that specifies the first client identifier and the first object identifier;

receiving a second object confirmation message from the first client device in response to sending the second object update message to the first client device; and

updating the client notification table accordingly, thereby assuring that the first client device is notified of the first object version of the first object.

21. The server system of claim 20, wherein the one or more programs further include instructions for:

when no second object update confirmation message is received from the first client device within a predefined span of time, resending the second object update message to the first client device.

22. A non-transitory computer readable-storage medium storing one or more programs for execution by one or more processors of a server system for managing objects for a web-based application hosted by one or more application servers, the one or more programs comprising instructions for:

receiving an object registration message from a first client device, the object registration message including;

a first client identifier corresponding to the first client device; and

a first object identifier corresponding to a first object cached at the first client device, wherein the first object is used by the web-based application;

updating an object-client registration table using the first client identifier and the first object identifier, thereby registering the first client device to receive notifications of updates to the first object;

receiving a first object update message that includes the first object identifier and a first object version number, wherein the first object update message corresponds to an update to the first object at a second client device while using the web-based application;

updating the object-client registration table to specify the first object version number as a current version of the first object;

and

in accordance with the registration of the first client device to receive notifications of updates to the first object, sending a second object update message to the first client device, wherein the second object update message includes the first object identifier and the first object version number;

wherein a last object update timestamp is stored when the first object update message is received, and the last object update timestamp is cleared upon receiving acknowledgement that object updates corresponding to the first object update message have been propagated, thereby assuring that the object updates are propagated even when the server has a failure.

23. The non-transitory computer readable-storage medium of claim 22, wherein the first object registration message includes a second object version number corresponding to the first object cached at the first client device, the one or more programs further comprising instructions for sending a third object update message to the first client device when the second object version number is less than the object'"'"'s version number in the object-client registration table.

24. The non-transitory computer readable-storage medium of claim 22, wherein the one or more programs include instructions for:

receiving an object deregistration message from the first client device, wherein the object deregistration message includes the first object identifier and the first client identifier; and

updating the object-client registration table in accordance with the object deregistration message, thereby preventing the server from sending subsequent object update messages for the first object to the first client device.

25. The non-transitory computer readable-storage medium of claim 22, wherein the one or more programs include instructions for:

receiving a fourth object update message that includes the first object identifier and a third version number of the first object;

when the third version number is less than or equal to the object'"'"'s version number in the object-client registration table, not updating the object-client registration table in response to the fourth object-update message; and

when the third version number is greater than the object'"'"'s version number in the object-client registration table;

updating the object-client registration table to specify the third version number as the current version of the first object; and

updating the stored last object update timestamp according to the fourth object update message, regardless of whether a most recently stored last object update timestamp has been cleared.

26. The non-transitory computer readable-storage medium of claim 22, wherein the one or more programs further include instructions that execute after updating the object-client registration table to specify the first object version number as the current version of the first object, the instructions for:

utilizing a client notification table to specify each of the client devices to update with the first object version of the first object, the client notification table including a separate record for each client device registered to receive updates to the first object, including a record that specifies the first client identifier and the first object identifier;

receiving a second object confirmation message from the first client device in response to sending the second object update message to the first client device; and

updating the client notification table accordingly, thereby assuring that the first client device is notified of the first object version of the first object.

27. The non-transitory computer readable-storage medium of claim 22, wherein the one or more programs further comprise instructions for:

when no second object update confirmation message is received from the first client device within a predefined span of time, resending the second object update message to the first client device.