| 摘要 |
<p>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.</p> |
