Client-based caching of remote files

• US 8,185,566 B2
• Filed: 01/15/2009
• Issued: 05/22/2012
• Est. Priority Date: 01/15/2009
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: George, Mathew, Kruse, David M., Pinkerton, James T., Jolly, Thomas E.
• Primary Examiner(s): Corrielus, Jean M
• Application Number:
  US12/353,982
• Publication Number:
  US 20100185704A1
• Time in Patent Office: 1,223 Days
• Field of Search: 707/821, 707/781, 709/225, 709/224, 714/15, 726/25
• US Class Current: 707/821
• CPC Class Codes: G06F 12/0813 with a network or matrix configuration
• CPC Class Codes: G06F 12/0815 Cache consistency protocols
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 16/172 Caching, prefetching or hoarding of files
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: G06F 16/183 Provision of network file services by network file servers, e.g. by using NFS, CIFS network file access protocols H04L67/1097
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 2212/264 Remote server
• CPC Class Codes: G06F 2212/463 File
• CPC Class Codes: G06F 2221/2141 Access rights, e.g. capability lists, access control lists, access tables, access matrices
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching

Abstract

A lease system is described herein that allows clients to request a lease to a remote file, wherein the lease permits access to the file across multiple applications using multiple handles without extra round trips to a server. When multiple applications on the same client (or multiple components of the same application) request access to the same file, the client specifies the same lease identifier to the server for each open request or may handle the request from the cache based on the existing lease. Because the server identifies the client'"'"'s cache at the client level rather than the individual file request level, the client receives fewer break notifications and is able to cache remote files in more circumstances. Thus, by providing the ability to cache data in more circumstances common with modern applications, the lease system reduces bandwidth, improves server scalability, and provides faster access to data.

Claims

1. A computer-implemented method for caching information at a client related to a remote file stored at a server, the method comprising:

receiving information from a software application indicating the remote file to open in an open request;

determining whether a lease exists on the client for the indicated remote file, wherein the lease provides a lease duration and cache coherency information associated with the indicated remote file;

when no lease exists on the client for the indicated remote file;

sending a lease request to open a handle to the indicated remote file and request the lease that identifies one or more cache intentions of the client based on the access information received from the software application; and

receiving a lease response indicating that the requested lease was granted;

upon an expiration of the lease duration corresponding to the lease, delaying the closing of the handle to the indicated remote file; and

wherein the preceding steps are performed by at least one processor.

2. The method of claim 1 wherein the open request comprises a UNC path to a remote file accessible over a network.

3. The method of claim 1 wherein determining whether a lease exists comprises looking up a UNC path associated with the remote file in a table of leases.

4. The method of claim 1 wherein sending a lease request comprises generating a lease identifier and sending the identifier to the server with the request.

5. The method of claim 1 wherein sending a lease request comprises providing one or more cache intentions in the lease request, wherein the cache intentions specify a manner in which the client accesses the remote file.

6. The method of claim 1 further comprising receiving file data and metadata for the requested remote file and storing the data and meta data in a local cache for later use.

7. The method of claim 1 further comprising determining whether a user associated with the current request is the same as a user associated with an existing lease, and when the user is different, requesting a new lease from the server.

8. The method of claim 1 further comprising, if an existing lease exists,

determining whether a scope of access requested to the remote file is compatible with a scope of the existing lease;

and

if the scope of the access requested is the same as the scope of the existing lease, collapsing the current open request on the existing lease, without making a round trip to the server.