System and method for providing transparent access to distributed authoring and versioning files including encrypted files

• US 7,437,429 B2
• Filed: 01/17/2002
• Issued: 10/14/2008
• Est. Priority Date: 02/13/2001
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Lin, Yun, Gu, Jianrong, Pardikar, Shishir, Garg, Praerit, Kumar, Rohan
• Primary Examiner(s): Vaughn, Jr.; William C.
• Assistant Examiner(s): Serrao; Ranodhi N
• Application Number:
  US10/052,039
• Publication Number:
  US 20030046366A1
• Time in Patent Office: 2,462 Days
• Field of Search: 709/219, 709/203, 707/203
• US Class Current: 709/219
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/0464 using hop-by-hop encryption, i.e. wherein an intermediate entity decrypts the information and re-encrypts it before forwarding it
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/563 Data redirection of data network streams
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

Access to WebDAV (Distributed Authoring and Versioning) servers is provided in a manner that is essentially transparent to applications. A WebDAV redirector and related components support file system I/O requests and network requests directed to WebDAV servers identified by URI (Universal Resource Identifier) names, or by a drive may be mapped to a WebDAV share. An application'"'"'s create or open I/O requests directed to a WebDAV server are detected, and result in a local copy of the file being downloaded and cached for local access. When closed, the local file is uploaded to the WebDAV server. Network-related requests such as for browsing that are directed to a WebDAV server are also handled transparently. WebDAV files may be locally encrypted and decrypted at the file system level, transparent to applications and the WebDAV server, via an encrypting file system that performs local encryption and decryption at the local file system level.

Claims

1. In a computer network, a method of automatically and transparently handling WebDAV server and file access requests, the method comprising:

maintaining at an I/O manager a predetermined, stored priority order that indicates which of a plurality of redirectors has precedence to handle a WebDAV I/O request, wherein a plurality of suitably configured redirectors respond to the WebDAV I/O request, each redirector being equally capable of redirecting the received WebDAV I/O request;

receiving at the I/O manager the WebDAV I/O request initiated from an application program, wherein the WebDAV I/O request indicates a path and filename of a remote file accessible via WebDAV;

polling available redirectors to determine which redirectors are configured to handle the application program'"'"'s WebDAV I/O file request, each redirector suitably configured to handle the WebDAV I/O request including appropriate functionality for receiving and redirecting WebDAV I/O file requests to corresponding WebDAV server computer systems that store the remote files;

receiving responses from the plurality of suitably configured redirectors, each suitably configured redirector being equally capable of redirecting the received WebDAV I/O file request;

determining from the stored priority order which of the plurality of suitably configured redirectors has precedence to handle the WebDAV I/O file request;

based on the determination, requesting a local file system of the redirector determined to have precedence to create the file in response to the WebDAV I/O file request, downloading the file to a local cache of the redirector'"'"'s file system, and returning a file handle corresponding to the file in the local cache to the application program;

providing access to the file in the local cache of the file system via the file handle;

receiving a request to close the file via the file handle, and when received, uploading the file from the local cache of the file system to the WebDAV server;

determining that the redirector determined to have precedence is configured to handle all similar WebDAV I/O requests to a network share; and

bypassing any redirector polling for subsequent requests directed to the network share.

2. The method of claim 1 wherein receiving an I/O request initiated from an application program comprises, receiving a Universal Resource Identifier corresponding to a file on the WebDAV server.

3. The method of claim 1 wherein receiving an I/O request initiated from an application program comprises, receiving a filename and an identifier previously mapped to a share on the WebDAV server.

4. The method of claim 1 wherein polling available redirectors to determine which redirectors are configured to handle the application program'"'"'s I/O request comprises, issuing an HTTP OPTIONS request, and evaluating a response therefrom.

5. The method of claim 1 wherein polling available redirectors to determine which redirectors are configured to handle the application program'"'"'s I/O request comprises, issuing a WebDAV PROPFIND request directed to a share on the WebDAV server, and evaluating a response therefrom.

6. The method of claim 5 wherein the WebDAV server returns property information in response to the WebDAV PROPFIND request directed to the share, and further comprising, maintaining the property information in a local data structure.

7. The method of claim 1 wherein polling available redirectors to determine which redirectors are configured to handle the application program'"'"'s I/O request comprises, issuing a WebDAV PROPFIND request directed to the file on the WebDAV server, and evaluating a response therefrom.

8. The method of claim 7 wherein the WebDAV server returns property information in response to the WebDAV PROPFIND request directed to the file, and further comprising, maintaining the property information in a local data structure.

9. The method of claim 1 wherein polling available redirectors to determine which redirectors are configured to handle the application program'"'"'s I/O request, comprises:

a) issuing an HTTP OPTIONS request, evaluating a corresponding response, and determining that the server is a WebDAV server;

b) issuing a WebDAV PROPFIND request directed to a share on the WebDAV server, evaluating a corresponding response, and determining that the share exists on the WebDAV server, the response including share property information; and

c) issuing a WebDAV PROPFIND request directed to the file, evaluating a corresponding response, and determining that the file exists, the response including file property information.

10. The method of claim 9 further comprising, maintaining the share property information and the file property information in at least one local data structure.

11. The method of claim 1 wherein polling available redirectors to determine which redirectors are configured to handle the application program'"'"'s I/O request, and further comprising, communicating with at least one other local component to indicate that at least this request can be handled.

12. The method of claim 1 further comprising, determining that the file is encrypted on the WebDAV server, and wherein downloading the file to a local cache of the file system comprises, communicating with the file system to create an image of the file in the local cache that is also encrypted.

13. The method of claim 12 further comprising, communicating with the file system to open the image of the file such that the file system will transparently decrypt file data on read requests and will transparently encrypt file data on write requests to the file.

14. The method of claim 12 wherein uploading the file from the local cache of the file system to the WebDAV server comprises, communicating with the file system to read data from the local image of the file such that the file will be uploaded as the encrypted image thereof.

15. A recordable computer-readable storage medium having computer-executable instructions for performing the method of claim 1.

16. The method of claim 1, wherein the priority order is based on server type.

17. The method of claim 16, wherein a different priority order is stored for each server type.

18. A computer-implemented method of automatically and transparently handling WebDAV server and file access requests, the method comprising:

maintaining at a local application programming interface layer a predetermined, stored priority order that indicates which of a plurality of redirectors has precedence to handle a WebDAV I/O request, wherein a plurality of suitably configured redirectors respond to the WebDAV I/O request, each redirector being equally capable of redirecting the received WebDAV I/O request;

receiving at the local application programming interface layer a WebDAV application I/O request comprising a WebDAV Uniform Resource Identifier (URI) indicating a path and filename of a remote file accessible via WebDAV;

polling available redirectors to determine which redirectors are configured to handle the WebDAV URI, each redirector suitably configured to handle the WebDAV application I/O request including appropriate functionality for receiving and redirecting WebDAV URI requests to corresponding WebDAV server computer systems that store the remote files;

receiving responses from the plurality of suitably configured redirectors, each suitably configured redirector being equally capable of redirecting the received WebDAV URI request;

determining from the stored priority order which of the plurality of responding redirectors has precedence to handle the WebDAV I/O URI request;

determining that the specified share and file are accessible;

based on the determination, handling the request, including;

requesting a local file system of the redirector determined to have precedence to create the file in response to the WebDAV I/O URI request;

downloading the file to a local cache of the redirector'"'"'s file system; and

returning a file handle corresponding to the file in the local cache to the WebDAV application program;

determining that the redirector determined to have precedence is configured to handle all similar WebDAV I/O requests to a network share; and

bypassing any redirector polling for subsequent requests directed to the network share.

19. The method of claim 18 wherein the application request includes the Universal Resource Identifier.

20. The method of claim 18 wherein the application request includes an identifier that has been previously mapped to at least part of the Universal Resource Identifier.

21. The method of claim 18 wherein the application request comprises an I/O request directed to a file, and wherein handling the request comprises creating a local file corresponding to the I/O request.

22. The method of claim 21 wherein handling the request further comprises, downloading at least some file data from the WebDAV server to the local file.

23. The method of claim 21 wherein handling the request further comprises, returning a file handle corresponding to the local file to the application.

24. The method of claim 18 wherein the application request comprises a networking request to browse a network share on the WebDAV server, and wherein handling the request includes enumerating information of the network share.

25. The method of claim 18 wherein the application program'"'"'s request indicates a share on the WebDAV server, and further comprising, issuing a WebDAV PROPFIND request directed to the share on the WebDAV server.

26. The method of claim 25 wherein the application program'"'"'s request further indicates a file on the share on the WebDAV server, and further comprising, issuing a WebDAV PROPFIND request directed to the file.

27. The method of claim 18 wherein the application request comprises an I/O request directed to an encrypted file, and further comprising, automatically decrypting the data locally when downloading the encrypted file from the WebDAV server and automatically encrypting the data locally when uploading the encrypted file to the WebDAV server.

28. The method of claim 18 wherein the application request comprises an I/O request directed to a file that is encrypted on the WebDAV server, and wherein handling the request comprises, creating a local file corresponding to the I/O request, and downloading an image of the file on the WebDAV server to the local file, wherein the local file is written by a local file system such that the image corresponds to the encrypted image on the WebDAV server.

29. The method of claim 28 further comprising, communicating with the file system to open the local file such that the file system will transparently decrypt file data read on read requests and will transparently encrypt file data written on write requests.

30. The method of claim 29 further comprising, detecting a request to close the local file, closing the local file, communicating with the files system to open the local file such that the file will not be decrypted when read, and uploading the file to the WebDAV server as an encrypted file.

31. A recordable computer-readable storage medium having computer-executable instructions for performing the method of claim 18.

32. In a computer network, a system including a processor and a memory for automatically and transparently handling WebDAV server and file access requests, the system comprising:

an application program that issues WebDAV-related requests, including at least one request having a WebDAV Uniform Resource Identifier (URI) corresponding to path and filename of a remote file stored on a WebDAV server;

a WebDAV redirector, the WebDAV redirector configured to respond to polls used to determine which redirectors are configured to handle the application'"'"'s WebDAV-related request, each redirector being suitably configured to handle the WebDAV I/O request including appropriate functionality for receiving and redirecting WebDAV I/O file requests to corresponding WebDAV server computer systems that store the remote files;

an I/O manager configured to perform the following;

maintain a predetermined, stored priority order that indicates which of a plurality of redirectors has precedence to handle a WebDAV I/O request, wherein the plurality of suitably configured redirectors respond to the WebDAV I/O request, each redirector being equally capable of redirecting the received WebDAV I/O file request, and that receives responses from the plurality of suitably configured redirectors;

determine from the stored priority order which of the plurality of suitably configured redirectors has precedence to handle the WebDAV I/O request and indicating that the WebDAV red irector locally handling each request corresponding to the WebDAV server can be handled locally and was determined to have precedence to create the file in response to the WebDAV I/O request, and communicate with the WebDAV server to handle requests that cannot be handled locally;

determine that the redirector determined to have precedence is configured to handle all similar WebDAV I/O requests to a network share; and

bypass any redirector polling for subseauent requests directed to the network share.

33. The system of claim 32 wherein the identifier corresponding to a WebDAV server issued by the application comprises a Universal Resource Identifier.

34. The system of claim 32 wherein the identifier corresponding to a WebDAV server issued by the application comprises an identifier previously mapped to a share on the WebDAV server.

35. The system of claim 32 wherein the WebDAV redirector receives requests from the application via an application programming interface.

36. The system of claim 32 wherein the application program issues I/O requests directed to a WebDAV file, and wherein the WebDAV redirector receives the 110 requests from a manager component.

37. The system of claim 32 wherein the application program issues I/O requests directed to a WebDAV file, and wherein the WebDAV redirector:

a) creates a local representation of the file;

b) determines whether the file exists on the WebDAV server, and if so, downloads at least some of the data from the WebDAV server file to the local representation of the file;

c) returns a file handle corresponding to the local representation of the file to the application program;

d) receives I/O read and write requests associated with the file handle and handles the I/O read and write requests via the local representation of the file; and

e) receives an I/O close request associated with the file handle, and handles the I/O close request by closing the local representation of the file and uploading at least part of the local representation of the file to the WebDAV server.

38. The system of claim 37 wherein the WebDAV file is encrypted, and wherein WebDAV redirector creates the local representation of the file by:

a) requesting the file system to create a local file that is opened such that transparent encryption and decryption are not enabled therefor,

b) downloading at least some of the encrypted file data by requesting the file system to write to the local file without translation thereof, and

c) requesting the file system to close the local file.

39. The system of claim 38 wherein the WebDAV redirector handles I/O read and write requests from the application by requesting the file system to reopen the local file such that reads therefrom are decrypted and writes thereto are encrypted.

40. The system of claim 39 wherein when the WebDAV redirector handles the I/O close request, and before uploading the file, the WebDAV redirector closes the local representation of the file, and reopens the local file by requesting the file system to open the file such that reads therefrom are not decrypted.