Systems and methods for detecting and resolving resource conflicts

• US 6,944,642 B1
• Filed: 10/04/1999
• Issued: 09/13/2005
• Est. Priority Date: 10/04/1999
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Anderson, Becky, Deen, Brian J., Hopmann, Alexander I.
• Primary Examiner(s): Follansbee, John
• Assistant Examiner(s): Nguyen, Dustin
• Application Number:
  US09/412,738
• Time in Patent Office: 2,171 Days
• Field of Search: 707/201, 707/100, 707/8, 707/103.R, 707/10, 709/222, 709/205, 709/221, 709/235, 709/328, 709/203, 710/8, 710/200, 713/201, 370/216
• US Class Current: 709/203
• CPC Class Codes: G06F 16/00 Information retrieval; Database structures therefor; File system structures therefor
• CPC Class Codes: G06F 16/1734 Details of monitoring file system events, e.g. by the use of hooks, filter drivers, logs
• CPC Class Codes: G06F 16/1767 Concurrency control, e.g. optimistic or pessimistic approaches
• CPC Class Codes: G06F 16/1787 Details of non-transparently synchronising file systems
• CPC Class Codes: G06F 16/2329 using versioning

Abstract

The present invention provides systems and methods for detecting and resolving resource conflicts. A resource conflict exists when a client version of a resource differs from a server version of the same resource. A resource conflict primarily arises when a client attempts to upload an altered resource to a server where the server version of the resource is no longer equivalent to the version that the client originally downloaded. The conflict is detected by the server and conflict resolution is initiated. The server is the first level of conflict resolution. The server can compare the conflicting versions of the resource to determine if the changes are not actually conflicting. If the server can resolve the conflict, it does and returns a resource tag to the client. The second level of conflict resolution is at the client. The client typically has knowledge of a schema related to the resource which may enable the client to resolve conflicts that the server could not. If the neither the server of the client can resolve the conflict, an end user is needed to resolve the conflict. After the conflict is resolved, it is uploaded to the server and the client receives a new resource tag.

Claims

1. In a system capable of replicating a server copy of a resource stored on one or more servers with a client copy of the resource stored on one or more clients, a method for resolving a resource conflict so that the client copy of the resource can be updated to the one or more servers without overwriting any changes made to the resource by another client, the method comprising the steps of:

determining that a conflict exists between the server copy of the resource and the client copy of the resource if a server resource tag that is representative of the server copy of the resource does not match a client resource tag that is representative of the client copy of the resource;

determining, at the server, whether the server can resolve the conflict between the server copy of the resource and the client copy of the resource into a single version of the resource;

creating, by the server, a conflict resource containing information about the conflict between the server copy and the client copy of the resource, if the conflict cannot be resolved at the server;

evaluating, at the client, whether the conflict resource can be resolved into a single version of the resource in accordance with additional information, known to the client but not the server, regarding a client operation that created the conflict, if the conflict was not resolved at the server; and

presenting the conflict resource to a user if the conflict resource cannot be resolved by the client.

2. The method as defined in claim 1, wherein the step of determining further comprises the step of resolving the conflict at the server.

3. The method as defined in claim 1, wherein the step of determining further comprises the step of comparing the client copy of the resource with the server copy of the resource.

4. The method as defined in claim 1, wherein the conflict resource comprises the server copy of the resource and the client copy of the resource.

5. The method as defined in claim 1, wherein the step of evaluating further comprises the step of resolving the conflict at the client in accordance with the schema.

6. The method as defined in claim 1, further comprising the steps of:

uploading the resolved conflict resource to the server; and

returning a new resource tag to the client from the server.

7. In a system capable of replicating a resource from one or more server to one or more clients, a computer program product for implementing a method of detecting and resolving resource conflicts so the one or more clients can upload the resource to the one or more servers without overwriting any changes made to the resource by another client, the computer program product comprising:

a computer readable medium carrying computer executable instructions for implementing the method, wherein the computer executable instructions comprise;

program code means for comparing a client resource tag with a server resource tag, wherein the client resource tag and the server resource tag are each representative of a version of the resource;

program code means for determining that no conflict exists between a client version of the resource and a server version of the resource if the client resource tag and the server resource tag match,

program code means for resolving a conflict at the server into a single version of the resource if the client resource tag and server resource tag fail to match;

program code means for creating conflict resource contain information about the conflict between the server copy and the client copy of the resource, if the conflict cannot be resolved at the server;

program code means for resolving the conflict at the client into a single version of the resource by evaluating the conflict resource in accordance with additional information, known to the client but not the server, regarding a client operation that created the conflict; and

program code means for presenting the conflict resource to an end user for conflict resolution if the client cannot resolve the conflict.

8. The computer program product as in claim 7, wherein the computer executable instructions further comprise:

program code means for uploading the resolved conflict resource to the server; and

program code means for providing the client with a new resource tag.

9. The computer program product as defined in claim 7, wherein the conflict resource comprises the server copy of the resource.

10. The computer program product as defined in claim 7, wherein the conflict resource comprises the server copy of the resource and the client copy of the resource.

11. The compute program product as defined in claim 7, wherein the conflict resource comprises a set of differences existing between the server copy of the resource and the client copy of the resource.

12. The computer program product as defined in claim 7, wherein the conflict resource comprises information useful to the client for resolving the conflict.

13. The computer program product as defined in claim 7, further comprising program code means for executing a server level of conflict resolution.

14. The computer program product as defined in claim 13, wherein the program code means for executing a server level of conflict resolution further comprises program code means for resolving the conflict.

15. The computer program product as defined in claim 7, further comprising program code means for executing a client level of conflict resolution which comprises program code means for comparing the changes made to the client copy of the resource and the server copy of the resource.

16. The computer program product as defined in claim 7, further comprising program code means for uploading the resolved conflict resource to the server.

17. The computer program product as defined in claim 16, further comprising program code means for returning to the client a new resource tag, wherein the new resource tag identified the current version of the server copy of the resource and the client version of the resource.

18. In a system capable or replicating a resource between a client and a server, a computer program product for implementing a method of detecting and resolving a conflict between a client copy of the resource and a server copy of the resource so that the client can upload the resource to the server without overwriting any changes made to the resource by another client, the computer program product comprising:

a computer readable medium carrying computer executable instructions for implementing the method, wherein the computer executable instructions comprise;

program code means for receiving a client resource tag at a server, the client resource tag identifying a client version of the client copy of the resource,

program code means for comparing, by the server, the client resource tag with a server resource tag that identifies a server version of the server copy of the resource,

program code means for determining that there is a conflict between the client copy of the resource and the server copy of the resource if the client resource tag does not match the server resource tag; and

program code means for executing one or more levels of conflict resolution until the conflict is resolved into a single version of the resource, wherein a first level of conflict resolution comprises a server level of conflict resolution, a second level of conflict resolution comprises a client level of conflict resolution and a third level of conflict resolution requires an end user to resolve the conflict.

19. The computer program product as in claim 18, wherein the program code means for executing one or more levels of conflict resolution further comprise:

program code means for executing a server level of conflict resolution to resolve a server copy of a resource and a client copy of a resource having one or more conflicts into a single version of the resource;

program code means for executing a client level of conflict resolution to resolve a server copy of a resource and a client copy of a resource having one or more conflicts into a single version of the resource; and

program code means for executing a third level of conflict resolution to thereby resolve a server copy of a resource and a client copy of a resource having one or more conflicts into a single version of the resource.

20. The computer program product as defined in claim 18, wherein the program code means for executing one or more levels comprises program code means for executing the server level of conflict resolution at the server.

21. The computer program product as defined in claim 18, wherein the program code means for executing one or more levels comprises program code means for executing the client level of conflict resolution at the client.

22. The computer program product as defined in claim 18, wherein the program code means for executing one or more levels comprises program code means for executing the third level of conflict resolution.

23. The computer program product as defined in claim 18, wherein the program code means for executing one or more levels comprises program code means for resolving the conflict in accordance with a schema.

24. The computer program product as defined in claim 23, wherein the schema is known to the server.

25. The computer program product as defined in claim 23, wherein the schema is known to the client.

26. The computer program product as defined in claim 18, wherein the program code means for executing one or more levels comprises program code means for uploading the resolved resource to the server and transmitting a new resource tag to the client.