Access requests with cache intentions

• US 8,732,202 B2
• Filed: 05/21/2013
• Issued: 05/20/2014
• 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:
  US13/899,373
• Publication Number:
  US 20130254492A1
• Time in Patent Office: 364 Days
• Field of Search: 707/821, 707/781, 707/822, 707/770, 709/225, 709/224, 709/203, 709/219
• US Class Current: 707/781
• 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-readable storage medium comprising instructions for controlling a computer system to cache information at a client related to remote files stored at a server, wherein the instructions, when executed at a client, cause at least one processor to perform actions comprising:

receiving access information from a software application indicating a 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 cache coherency information associated with the remote file;

if no lease exists, sending a lease request to open the file and request a lease that identifies one or more cache intentions of the client based on the access information received from the application; and

receiving a lease response indicating whether the requested lease was granted.

2. The computer-readable storage medium of claim 1 wherein the open request comprises a Uniform Naming Convention (UNC) path to the remote file accessible over a network.

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

4. The computer-readable storage medium of claim 1 wherein sending the lease request comprises generating a lease identifier and sending the identifier to the server with the request.

5. The computer-readable storage medium of claim 1 wherein sending a lease request comprises providing one or more cache intentions in the lease request, wherein the cache intentions specify data associated with client access of the remote file.

6. The computer-readable storage medium 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 computer-readable storage medium 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 computer-readable storage medium 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 access requested is the same as the scope of the existing lease, collapsing the current open request onto the existing lease, without making a round trip to the server.

9. A system comprising:

a processor and memory configured to execute software instructions;

an application interface configured to provide an interface through which one or more applications submit one or more requests to open remote files on the remote server and receive file data;

a lease request component, responsive to the application interface, that is configured to send lease requests to the remote server and handle received lease responses, wherein the lease requests sent to the remote server include cache coherency information associated with the remote files and are based on information submitted by the one or more applications;

a communication component configured to transmit the lease requests and receive lease responses and the file data over a network that connects one or more clients and the remove server;

a cache component configured to cache the file data at the client based on information received from the remote server; and

a break handling component configured to respond to break notifications received from the remote server, wherein a break notification indicates that access that the remote server previously granted to the client is no longer compatible with access requests of the other clients accessing at least one of the one or more remote files.

10. The system of claim 9 wherein the application interface provides a kernel mode interface for communicating with the remote server.

11. The system of claim 9 wherein the application interface is further configured to receive requests to access the remote files.

12. The system of claim 9 wherein the application interface is further configured to provide file data to the one or more applications directly from the cache component without additional communication with the remote server when the file data is available from the cache component.

13. The system of claim 9 wherein the lease request component is further configured to receive responses from the remote server that either grant or deny a lease and, when the lease is denied, that suggest a scope of access for the lease that is lower than a requested access level.

14. The system of claim 9 wherein the communication component is further configured to use extensions to the Server Message Block version 2 network protocol.

15. The system of claim 9 wherein the cache component is further configured to associate a lease identifier with each cache so that the remote server can distinguish one cache provider from another.

16. The system of claim 9 wherein the break handling component is further configured to update the remote server based on use of a remote file related to the break notification by applications on the client.

17. The system of claim 9 wherein the application interface is further configured to include a lease identifier when submitting to the lease request component the one or more requests to open remote files on the remote server and receive file data.

18. The system of claim 9 wherein the application interface is further configured with an interface that permits the one or more applications to cache data received from the remote server based on the terms of received leases.

19. A method for controlling a computer system to cache information at a client related to remote files stored at a server, the method comprising:

receiving access information from a software application indicating a 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 cache coherency information associated with the remote file;

if no lease exists, sending a lease request to open the file and request a lease that identifies one or more cache intentions of the client based on the access information received from the application; and

receiving a lease response indicating whether the requested lease was granted.

20. The method of claim 19 wherein sending a lease request comprises providing one or more cache intentions in the lease request, wherein the cache intentions specify data associated with client access of the remote file.