Method, computer readable medium, and system for monitoring the state of a collection of resources

• US 6,694,335 B1
• Filed: 10/04/1999
• Issued: 02/17/2004
• Est. Priority Date: 10/04/1999
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Anderson, Rebecca L., Deen, Brian J., Hopmann, Alexander I.
• Primary Examiner(s): Corrielus, Jean M.
• Application Number:
  US09/412,739
• Time in Patent Office: 1,597 Days
• Field of Search: 709/203, 709/205, 709/202, 709/200, 709/217, 709/223, 707/201, 707/203, 707/6, 707/7, 707/3, 707/101, 707/102, 707/104
• US Class Current: 707/624
• CPC Class Codes: G06F 16/275 Synchronous replication
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99937 Sorting
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A system and method for synchronizing changes among multiple copies of data is disclosed. The system and method allows the data to be synchronized without any copying or transferring of those portions of the data that have not been changed. In particular, the system and method preferably uses an identifier to represent the current state of the data and the identifier is used to determine what, if any, changes have occurred to the data. Thus, instead of comparing the data itself to see if changes have been made, the identifier is used to simply and easily determine if changes were made to the data. Each identifier preferably includes a first portion that identifies a particular source for the data and a second portion that includes a change number that is changed each time the underlying resource is modified. The identifier is preferably opaque or transparent to the client such that the client does not have to understand anything about the format or use of the identifier. Advantageously, an opaque identifier allows the system and method to be compatible with a wide range of data and programs.

Claims

1. A method of synchronizing two or more copies of data between two or more components, one copy of the data being stored in a first component and another copy of the data being stored in a second component, the method comprising the steps of:

generating a synchronization request, the synchronization request including an identifier which identifies the state of a collection of resources in the first component;

communicating the synchronization request from the first component to the second component;

generating an identifier for the second component which identifies the state of a collection of resources in the second component; and

comparing the identifier for the first component with the identifier for the second component to determine if the resources in the second component are generally the same as the resources in the first component.

2. The method of claim 1, wherein if the identifier of the first component is generally the same as the identifier of the second component, then the components are generally synchronized and no copies of the resources are communicated between the components.

3. The method of claim 1, further comprising the step of using the identifiers to form manifests which minimize the processing needed to accomplish the synchronization.

4. The method of claim 1, further comprising the step of using the identifiers to determine which of the resources in the collections of the resources need to be synchronized.

5. The method of claim 1, wherein each identifier includes a first portion and a second portion, the first portion including a source identification and the second portion including a change number.

6. The method of claim 1, wherein each identifier is opaque to the first component.

7. The method of claim 1, wherein only resources that contain one or more incremental changes are synchronized and all other unchanged resources are not synchronized.

8. A method of synchronizing two or more copies of data, one copy of the data being stored on a first machine and another copy of the data being stored on a second machine;

the method comprising;

generating a synchronization request at the first machine, the synchronization request including a first identifier that indicates the state of a collection of data at the first machine;

communicating the synchronization request to the second machine;

comparing the first identifier with a second identifier that indicates the state of a collection of data at the second machine to determine incremental changes between the data stored on the first machine and the data stored on the second machine; and

transmitting only the incremental changes in the data between the first machine and the second machine so that the copies of the data are synchronized.

9. The method of claim 8, wherein the first machine is a client machine and the second machine is server machine.

10. The method of claim 8, wherein the identifier includes a first portion that identifies the source of the data and a second portion that includes a change number.

11. A method of synchronizing two or more copies of data, one copy of the data being stored on a first machine and another copy of the data being stored on a second machine, the method comprising:

transmitting a synchronization request from the first machine to the second machine, the synchronization request including a first manifest indicating the state of the data stored on the first machine;

receiving the synchronization request and the first manifest at the second machine;

comparing the first manifest with a second manifest indicating the state of the data stored on the second machine;

identifying incremental changes in the copies of the data on the first machine and the second machine from the comparison of the first manifest and the second manifest; and

communicating copies of the incremental changes between the first and second machines such that the copies of the data are synchronized.

12. The method of claim 11, further comprising transmitting the second manifest from the second machine to the first machine after the data is synchronized.

13. The method of claim 11, wherein only the synchronization request incremental changes in the data, first manifest and second manifest are communicated between the first machine and the second machine.

14. The method of claim 11, wherein the first manifest and the second manifest include one or more identifiers that identify individual elements in the data.

15. The method of claim 11, wherein the identifiers are opaque to the first machine.

16. The method of claim 11, wherein the first and second manifests are opaque to the first machine.

17. The method of claim 11, wherein the first manifest is empty during an initial synchronization request.

18. A method of synchronizing two or more copies of data, one copy of the data being stored on a first machine and another copy of the data being stored on a second machine;

the method comprising the steps of;

communicating a synchronization request from the first machine to the second machine;

comparing a first identifier that represents data stored on the first machine with a second identifier that represents data stored on the second machine to determine if the data needs to be synchronized; and

communicating only the data the needs to be synchronized from the second machine to the first machine.

19. The method of claim 18, further comprising the step of communicating the first identifier from the first machine to the second machine before comparing the first and second identifiers, and communicating the second identifier to the first machine after comparing the first and second identifiers.

20. A method of synchronizing a second set of data with a first set of data that has had incremental changes made thereto, the incremental changes being made only to the first set of data and not the second set of data, the method comprising the steps of:

comparing a first manifest that indicates a current state of the first set of data with a second manifest that indicates a current state of the second set of data;

determining the incremental changes in the first set of data that need to be synchronized with the second set of data based on the comparison of the first manifest and the second manifest; and

communicating only those incremental changes in the first set of data with the second set of data so that the first set of data and the second set of data are synchronized.

21. The method of claim 20, wherein the first manifest and the second manifest comprise a list of one or more tokens, each of the tokens representing the current state of an individual element in the first set of data or the second set of data.

22. A computer-readable medium having computer-executable instructions for performing steps comprising:

communicating a synchronization request from a first machine to a second machine;

receiving the synchronization request at the second machine;

calculating a manifest that indicates the current state of a collection of resources in the second machine;

comparing the manifest for the second machine with a manifest for the first machine, the manifest for the first machine indicating the current state of a collection of resources in the first machine;

identifying incremental differences between the collection of the resources in the first machine and the second machine based upon the differences between the manifests; and

communicating the incremental differences in the collection of resources between the second machine and the first machine so that the collection of resources in the first machine is synchronized with the collection of resources in the second machine.

23. The computer-readable medium of claim 22 having further computer-executable instructions for performing the step of communicating only those resources stored in the first machine with the second machine that are necessary to synchronize the collection of resources between the first machine and the second machine.

24. The computer-readable medium of claim 22 having further computer executable instructions for performing the step of communicating the manifest from the second machine to the first machine after the collection of resources is synchronized.

25. A computer-readable medium having computer-executable instructions for performing steps comprising:

communicating a synchronization request from a first machine to a second machine, the synchronization request including a manifest indicating the current state of a collection of resources stored at the first machine;

calculating a manifest indicating the current state of a collection of resources stored at the second machine;

comparing the manifest for the first machine with the manifest for the second machine;

determining the resources that need to be copied from the first machine and the second machine based on the comparison of the manifests; and

communicating only those resources which need to be synchronized between the first machine and the second machine.

26. The computer-readable medium of claim 25 having further computer-executable instructions for performing the step of communicating the newly calculated manifest from the second machine to the first machine.

27. The computer-readable medium of claim 25 having further computer-executable instructions for performing the step of returning an error message to the first machine if the manifest indicating the state of the collection of resources in the first machine is invalid.

28. A method of synchronizing resources between a client machine and a server machine, wherein only resources that contain incremental changes are synchronized and resources than are unchanged are not synchronized, the method comprising the steps of:

connecting the client machine to the server to allow communication between the client machine and the server machine;

copying appropriate resources from the server machine to the client machine;

disconnecting the client machine from the server machine;

reconnecting the client machine to the server machine; and

synchronizing only the incremental changes to the resources between the client machine and the server machine.

29. The method of claim 28, further comprising the step of communicating a first identifier from the client to the server, the first identifier indicating the state of the resources in the client.

30. The method of claim 28, further comprising the steps of calculating a second identifier that indicates the state of resources at the server, and comparing the first identifier with the second identifier to determine the incremental changes to the resources.

31. The method of claim 28, wherein the first identifier is opaque to the client.

32. The method of claim 28, wherein the first identifier and the second identifier each contain a first portion and a second portion, the first portion including a source identification and the second portion including a change number.

33. The method of claim 28, wherein the change number is changed each time there is a change to the corresponding resource.

34. The method of claim 28, wherein the identifier is unique to each resource.

35. The method of claim 28, wherein the first portion of the identifier identifies a particular server.

36. A method of synchronizing a second copy of data with a first copy of the data, the first copy of the data including incremental changes that have not been incorporated into the second copy of the data, the method comprising:

calculating a first identifier for the first copy of the data, the first identifier indicating the contents of the first copy of the data;

calculating a second identifier for the second copy of the data, the second identifier indicating the contents of the second copy of the data;

comparing the first identifier and the second identifier for controlling transfer of the incremental changes from the first copy of the data to the second copy of the data; and

synchronizing the incremental changes from the first copy of the data to the second copy of the data.

37. A computer-readable medium having computer-executable instructions for performing steps comprising:

means for identifying the contents of a first collection of resources;

means for identifying the contents of a second collection of resources;

means for comparing the contents of the second collection of resources with the first collection of resources to determine incremental changes between the first and second collection of resources; and

synchronizing the incremental changes between the first and second collection of resources.

38. A system for synchronizing a second copy of data located in second component with a first copy of the data located in a first component, the first copy of the data including incremental changes that have not been incorporated into the second copy of the data, the system comprising:

a data transferring system comprising;

means for identifying the contents of a first collection of resources;

means for identifying the contents of a second collection of resources; and

means for comparing the contents of the second collection of resources with the first collection of resources to determine incremental changes between the first and second collection of resources; and

means for synchronizing the incremental changes between the first and second collection of resources.