| 摘要 |
Methods and computer program products for using a front-end server to access content stored on one or more back-end servers. The front-end server receives requests for content from client systems. Back-end servers store the content, but to the client system, it appears as if the front-end server is the content's source. Upon receiving the request, the front-end server checks the validity of the request and examines a global catalog that dynamically maps client system requests to the back-end server or servers that store the requested content. In some circumstances, the content will be stored at a single back-end server and the front-end server directs the request to that server. Alternatively, a list of back-end servers storing the requested content may be generated. If so, the front-end then uses an authentication token as a key to a hash operation that is performed on the list and a single server that is capable of satisfying the request for content is identified. A given request and authentication token always identify the same server if the list of servers available for providing the requested content remains the same. The front-end server provides a single source for content requests so that client systems are not required to alter requests or invalidate local caches when content is moved from one back-end server to another. The front-end server also provides an additional level of security for back-end servers.
|
