Method and system for synchronizing data shared among peer computing devices

• US 7,743,022 B2
• Filed: 02/28/2003
• Issued: 06/22/2010
• Est. Priority Date: 02/28/2003
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Saathoff, Jeffrey M., Guzak, Chris J., Raman, Balan Sethu, Chitre, Sudarshan A., Flo, Eric R., Kaasten, Shaun A., Moore, Jason F., Orbits, David A.
• Primary Examiner(s): Fleurantin; Jean B.
• Assistant Examiner(s): MYINT, DENNIS Y
• Application Number:
  US10/376,430
• Publication Number:
  US 20040172423A1
• Time in Patent Office: 2,671 Days
• Field of Search: 707/1, 707/201, 707/204, 707/613, 395/610, 709/204, 358/400, 719/330
• US Class Current: 707/612
• CPC Class Codes: G06F 16/1787 Details of non-transparently synchronising file systems

Abstract

Disclosed is a data synchronization service for use in a peer-to-peer computing environment. Selected data objects are copied onto selected computing devices. A service running on each device monitors data objects for changes. When a change is detected, the service sends a change notification to the other devices so that they can update their copies of the data object. A user can access a data object from any device, knowing that he will retrieve the latest version of the data object. Instead of incurring the costs of storing a large file on every device, a user “ghosts” the file on some devices. A ghosting device stores only metadata about the file rather than the entire file. The user accesses the file through the ghost: access requests are sent to a device that holds the actual contents, and those contents are presented to the user as if they were stored locally.

Claims

1. A computer-implemented method of synchronizing data in a peer to peer computer system having a processor, memory, and a data storage subsystem, the computer-implemented method comprising:

providing a plurality of computing devices in the peer to peer computer system, the computing devices comprising a peer computing device and a counterpart peer computing device;

designating one of the computing devices as a change notification clearing house;

configuring a synchronization between the peer computing device comprising a peer data object and the counterpart peer computing device comprising a counterpart peer data object;

monitoring the peer data object by a synchronization service of the peer computing device for changes;

detecting a change in the peer data object of the peer computing device by the synchronization service of the peer computing device;

transmitting a change notification of the change in the peer data object from the synchronization service of the peer computing device to the change notification clearing house, wherein the transmitting step occurs via an input/output manager, a plurality of file system drivers, and a plurality of communications channels;

checking a status of the transmitted change notification;

listening for changes to the counterpart peer data object;

receiving a change notification via the change notification clearing house of a change to the counterpart peer data object from a synchronization service of the counterpart peer computing device;

applying the change of the counterpart peer data object to the peer data object on the peer computing device; and

sending a status of the applied change from the peer computing device to the counterpart peer computing device via the change notification clearing house.

2. The computer-implemented method of claim 1, further comprising:

checking the counterpart peer computing device for authorization to synchronize with the peer computing device.

3. The computer-implemented method of claim 1, further comprising:

setting up encryption parameters for communications between the peer computing device and the counterpart peer computing device.

4. The computer-implemented method of claim 1, further comprising:

bringing the peer data object and the counterpart peer data object into a same state.

5. The computer-implemented method of claim 4, wherein bringing the peer data object and the counterpart peer data object into a same state comprises:

if data of the peer data object is newer than data of the counterpart peer data object, or if the counterpart peer data object does not exist, then transmitting a copy of the peer data object from the peer computing device to the counterpart peer computing device;

else if the data of the counterpart peer data object is newer than the data of the peer data object, or if the peer data object does not exist, then receiving a copy of the counterpart peer data object from the counterpart peer computing device, and updating the peer data object from the received copy of the counterpart peer data object.

6. The computer-implemented method of claim 4, wherein the peer data object comprises a first folder and the counterpart peer data object comprises a second folder, and wherein bringing the peer data object and the counterpart peer data object into the same state comprises:

bringing a third data object located within the first folder into a same state as a corresponding fourth data object located within the second folder; and

receiving copies of the peer data object and the counterpart peer data object from the counterpart peer computing device, and if there is no corresponding data object within the first folder for each of the received copies, then creating a new data object within the first folder from the received copy.

7. The computer-implemented method of claim 1, wherein monitoring the peer data object comprises monitoring a first file for at least one of the following changes:

an attribute of the first file is modified, data in the first file is modified, the first file is moved, and the first file is deleted.

8. The computer-implemented method of claim 1, wherein monitoring the peer data object comprises monitoring a first folder for at least one of the following changes:

an attribute of the first folder is modified, a third data object is created within the first folder, the first folder is moved, and the first folder is deleted.

9. The computer-implemented method of claim 8, further comprising:

monitoring the third data object within the first folder for changes.

10. The computer-implemented method of claim 9, wherein the changes to the third data object within the first folder comprise:

an attribute of the third data object is modified, data in the third data object is modified, a fourth data object is created within the third data object, the third data object is moved, and the third data object is deleted.

11. The computer-implemented method of claim 9, further comprising:

if the third data object changes, then transmitting a notification of the change to the counterpart peer computing device.

12. The computer-implemented method of claim 1, wherein if the detecting a change in the peer data object of the peer computing device has an unexpected effect on the counterpart peer computing device, then warning a user of the peer computing device of the unexpected effect, the unexpected effect corresponding to an unanticipated modification to either the counterpart peer data object or its contents.

13. The computer-implemented method of claim 12, wherein:

the peer data object comprises a first folder and the counterpart peer data object comprises a second folder;

the change in the first folder comprises moving a third data object from within the first folder to a first location outside the first folder; and

warning a user comprises warning that the change would delete a fourth data object in the second folder, the fourth data object corresponding to the third data object, without creating a new data object on the counterpart peer computing device in a second location corresponding to the first location on the peer computing device.

14. The computer-implemented method of claim 12, wherein:

the peer data object comprises a first folder and the counterpart peer data object comprises a second folder;

the change in the first folder comprises moving a third data object from a first location outside the first folder to within the first folder; and

warning a user comprises warning that the change would create a new data object within the second folder, the new data object corresponding to the third data object, without deleting a fourth data object on the counterpart peer computing device in a second location corresponding to the first location on the peer computing device.

15. The computer-implemented method of claim 1, further comprising:

configuring a synchronization between the peer data object and a third data object on a third peer computing device;

if the peer data object is changed, then transmitting a notification of the change to the peer data object to the third peer computing device;

listening for a notification from the third peer computing device of a change to the third data object; and

if a notification of a change to the third data object is received, then applying the received change of the third data object to the peer data object.

16. The computer-implemented method of claim 1, wherein the peer data object comprises a ghost file, and a change of deleting, moving, or renaming the peer data object consists of deleting, moving, or renaming the ghost file, respectively.

17. The computer-implemented method of claim 1, wherein the peer data object comprises a ghost file, and a change to the peer data object is synchronized with the counterpart peer data object, wherein the change does not consist of deleting, moving, or renaming the ghost file.

18. A computer-implemented method of synchronizing data in a peer to peer computer system having a processor, memory, and a data storage subsystem, the computer-implemented method comprising:

providing a plurality of computing devices in the peer to peer computer system, the computing devices comprising a peer computing device and a counterpart peer computing device;

designating one of the computing devices as a change notification clearing house;

initiating data synchronization of a folder located within a peer data object of the peer computing device with the counterpart peer computing device comprising a counterpart peer data object, wherein the peer computing device and the counterpart peer computing device comprise a synchronization set;

initializing a data synchronization service on the peer computing device;

determining, via an application program interface of the peer computing device, if the folder is already being synchronized;

managing the data synchronization of the folder by the application program interface of the peer computing device, via an object of the synchronization set;

initializing a data synchronization service on the counterpart peer computing device;

determining, via an application program interface of the counterpart peer computing device, if a counterpart to the folder is already being synchronized on the counterpart peer computing device;

sending configuration information via the change notification clearing house to the counterpart peer computing device, wherein the counterpart peer computing device hosts synchronized copies of the folder; and

synchronizing changes of the folder on the peer computing device with the counterpart folder located on the counterpart peer computing device, wherein the synchronizing changes comprises a combination of full copy synchronization and ghost copy synchronization.

19. The computer-implemented method of claim 18, wherein the synchronizing changes further comprises:

a full copy synchronization of the folder on the peer computing device with the counterpart folder located on the counterpart peer computing device, and a ghost copy synchronization of a file contained within the folder on the peer computing device with a file contained within the counterpart folder located on the counterpart peer computing device.

20. The computer-implemented method of claim 18, wherein the synchronizing changes further comprises:

a full copy synchronization of the folder on the peer computing device with the counterpart folder located on the counterpart peer computing device, and a ghost copy synchronization of the folder on the peer computing device with a folder on a third device.

21. The computer-implemented method of claim 18, wherein the synchronizing changes further comprises:

a full copy synchronization of metadata and attributes within the folder located on the peer computing device with the counterpart folder located on the counterpart peer computing device, and a ghost copy synchronization of bulk file changes made to the folder on the peer computing device with the counterpart folder located on the counterpart peer computing device.

22. The computer-implemented method of claim 18, further comprising:

transmitting a collection of notifications of changes to the peer data object via the change notification clearing house from the peer computing device to the counterpart peer computing device on a basis comprising one of;

a schedule, availability of the peer computing device to transmit notifications, and availability of the counterpart peer computing device to receive notifications.

23. The computer-implemented method of claim 18, further comprising:

pausing a command to remove the peer computing device from the synchronization set until synchronization with the counterpart peer computing device is completed.

24. A system for synchronizing data in peer to peer computing systems having processors, memories and data storage subsystems, at least one of said peer to peer computing systems comprising:

a file system comprising a plurality of data objects and a data synchronization service;

a data synchronizer operable to detect changes in the plurality of data objects;

an input/output manager to configure a plurality of communications channels, operable to transmit change notifications to a corresponding counterpart peer computing system, the change notifications received from file system drivers coupled to the data synchronizer; and

a plurality of local storage drivers operable to apply changes to the plurality of data objects, resulting from changes made to corresponding data objects in the corresponding counterpart peer computing system, wherein the change notifications are transmitted over the communications channels configured by the input/output manager.

25. The system of claim 24, wherein one of the plurality of data objects comprises a ghosted file containing attributes and metadata of a corresponding full copy remote file located in the counterpart peer computing system, and wherein changes to the attributes and metadata of the ghosted file are synchronized to the corresponding data objects of the full copy remote file in the counterpart peer computing system.