Optimizing file replication using binary comparisons

• US 8,200,623 B2
• Filed: 03/19/2007
• Issued: 06/12/2012
• Est. Priority Date: 11/06/2003
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Liu, Hai, Antonoff, Lauren
• Primary Examiner(s): Ehichioya, Fred I
• Assistant Examiner(s): Rahman, Sabana
• Application Number:
  US11/725,311
• Publication Number:
  US 20070174351A1
• Time in Patent Office: 1,912 Days
• Field of Search: 707/610, 707/638, 707/695
• US Class Current: 707/610
• CPC Class Codes: G06F 16/1767 Concurrency control, e.g. optimistic or pessimistic approaches
• CPC Class Codes: G06F 16/178 Techniques for file synchronisation in file systems
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

Client and server based copies of a file are maintained in synchronicity as changes are made to the file. Data is compared to a previous version known to both the client and server and a highly compressed representation of the differences between the two is generated. These differences, or “diffs”, are then transmitted, and may use extensions to the HTTP (HyperText Transport Protocol) protocol.

Claims

1. A system for use in a file synchronization system, comprising:

a storage device for storing a first copy and a second copy of a base file;

an input device for receiving changes to the first copy of the base file;

a processor for changing the first copy based on the received changes, and

determining a difference between the changed first copy and the second copy; and

an output device for transmitting the difference to a server,

wherein if the difference is rejected by the server because an additional difference has been previously applied to the base file, then the input device receives the additional difference from the server, and the processor applies the additional difference to the second copy of the base file,

wherein the processor applies the additional difference to the second copy of the base file to generate a modified second copy, applies the received changes to the modified second copy to generate a third copy, and determines a third difference between the third copy and the modified second copy.

2. The system of claim 1, wherein the difference is a binary difference.

3. The system of claim 1, wherein the base file resides on the server.

4. The system of claim 1, wherein the difference is transmitted to the server using extensions to the HTTP protocol.

5. The system of claim 1, further comprising an output device for transmitting the third difference to a server.

10. The system of claim 1, wherein the processor for determining the difference between the changed first copy and the second copy is associated with a client device.

6. A system for use in a file synchronization system, comprising:

a storage device for storing a base file;

an input device for receiving a first difference from a first client and a second difference from a second client, the first difference being received before the second difference;

a processor for determining if the first difference is applicable to the stored base file, and if so, applying the first difference to the base file and rejecting the second difference because of application of the first difference to the base file; and

an output device for transmitting a third difference from the server to the second client, the third difference being applied to a copy of the base file stored at the second client,

wherein the third difference is applied to a first copy of the base file at the second client to generate a modified first copy, and the second difference is applied to the modified first copy to generate a second copy, and a fourth difference is determined between the second copy and the modified first copy.

7. The system of claim 6, wherein the first difference is a binary difference.

8. The system of claim 6, wherein the first difference is received in the form of extensions to the HTTP protocol.

9. The system of claim 6, wherein the first difference is applicable to the stored base file if the base file is the same as a client base file that the first client used to generate to the first difference.