Data access

• US 20030033283A1
• Filed: 08/26/2002
• Published: 02/13/2003
• Est. Priority Date: 03/22/2000
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Evans, Paul A, Cobley, Richard J
• Granted Patent: US 7,191,180 B2
• Time in Patent Office: Days
• US Class Current: 707/1
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 67/5681 Pre-fetching or pre-delivering data based on network characteristics
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

A data access system is provided, including proxy servers (100) for caching “local” copies of selected data sets stored on data servers (115) to which users request access. Each proxy server (100) is adapted to generate (135) a subscription request message in respect of each identified cached data set for submission to a conventional “publish & subscribe” data distribution system (110). The data distribution system (110) is arranged with access to “published” updates to data sets, made available from respective data servers (115). Upon receipt of a published updated data set having an identifier matching that in an earlier-received subscription request, the data distribution system (110) forwards the data set to the subscribing proxy server (100) to enable update to the respective cached copy. Thus, a proxy server (100), having decided to cache a particular data set, need only issue a subscription request message in order to receive all subsequent updates, as they become available, until choosing to remove the data set from the cache.

Claims

1. A file server for retrieving and transmitting files in response to received requests, in a communications network, the file server comprising:

i) a request input for receiving file requests from client equipment;

ii) request monitoring means for monitoring received file requests;

iii) a subscription request output;

iv) file retrieval means for retrieving a file identified in a received file request from a first location and transmitting it to the client equipment making the request; and

v) a cache for storing local copies of files for which file requests have been received;

wherein the request monitoring means is arranged to monitor received file requests, and, in the event of a predetermined condition being met for a file identified by at least one request, to trigger the subscription request output to output a subscription request for the identified file to a second location.

2. A file server according to claim 1 wherein the predetermined condition comprises a threshold number of requests for the identified file.

3. A file server according to claim 1 wherein the predetermined condition comprises a threshold rate of requests for the identified file.

8. A data access system according to claims 1, 4 and 7.

4. A data access system for providing updated files in response to received file requests, the system comprising:

i) a subscription service file server which provides a subscription service to at least one caching file server, the subscription service file server being provided with a log for logging subscription data against respective caching file servers in respect of selected files or categories of files; and

ii) access to a source file server which provides updates to files to the subscription service file server;

said subscription service file server being triggerable, on receipt of an update to a file, to send a copy of the update to each caching file server logged in respect of that file.

5. A system according to claim 4 wherein said log is arranged to log caching file servers against individual file identifiers.

6. A system according to claim 4 wherein said log is arranged to log caching file servers against file categories.

7. A data access system for use in providing updated files in response to received file requests, the system comprising a source file server which provides a file updating service to at least one destination file server, the source file server being provided with:

i) update detection means for monitoring one or more files stored by the source file server to detect an update thereto;

ii) a destination server log for logging destination information with respect to one or more destination file servers;

iii) file selection means for selecting files to be monitored by the update detection means; and

means triggerable by a detected update to a file to output a copy of the update to any destination file server having destination information logged in respect of it.