Reverse Caching Proxy (default configuration)
When using a reverse proxy configuration, Caching Proxy machines are located between the Internet and the enterprise's content hosts. Acting as a surrogate, the proxy server intercepts user requests arriving from the Internet, forwards them to the appropriate content host, caches the returned data, and delivers that data to the users across the Internet. Caching enables Caching Proxy to satisfy subsequent requests for the same content directly from the cache, which is much quicker than retrieving it again from the content host. Information can be cached depending on when it will expire, how large the cache should be and when the information should be updated. Faster download times for cache hits mean better quality of service for customers. Figure 1 depicts this basic Caching Proxy functionality.
In this configuration, the proxy server (4) intercepts requests whose URLs include the content host's host name (6). When a client (1) requests file X, the request crosses the Internet (2) and enters the enterprise's internal network through its Internet gateway (3). The proxy server intercepts the request, generates a new request with its own IP address as the originating address, and sends the new request to the content host (6).
The content host returns file X to the proxy server rather than directly to the end user. If the file is cacheable, Caching Proxy stores a copy in its cache (5) before passing it to the end user. The most prominent example of cacheable content is static Web pages; however, Caching Proxy also provides the ability to cache and serve content dynamically generated by WebSphere® Application Server.