Caching Proxy
Caching Proxy reduces bandwidth use and improves a Web site's speed and reliability by providing a point-of-presence node for one or more back-end content servers. Caching Proxy can cache and serve static content and content dynamically generated by WebSphere® Application Server.
Caching Proxy can be configured in the role of a reverse proxy server (default configuration) or a forward proxy server, providing either a point-of-presence for a network or an internal network server that is responsible for improving request and response time. For more information on reverse and forward configurations, see Basic Caching Proxy configurations.
The proxy server intercepts data requests from a client, retrieves the requested information from content-hosting machines, and delivers that content back to the client. Most commonly, the requests are for documents stored on Web server machines (also called origin servers or content hosts) and delivered using the Hypertext Transfer Protocol (HTTP). However, you can configure the proxy server to handle other protocols, such as File Transfer Protocol (FTP) and Gopher.
The proxy server stores cacheable content in a local cache before delivering it to the requester. Examples of cacheable content include static Web pages and JavaServer Pages files that contain dynamically generated, but infrequently changing, information. Caching enables the proxy server to satisfy subsequent requests for the same content by delivering it directly from the local cache, which is much quicker than retrieving it again from the content host.
Plug-ins for Caching Proxy add functionality to the proxy server.
- The ICP plug-in enables the proxy server to query Internet Caching Protocol (ICP)-compliant caches in search of HTML pages and other cacheable resources.
- The Tivoli® Access Manager (formerly Policy Director) plug-in enables the proxy server to use Access Manager's integrated authorization or authentication services.
- The PAC-LDAP Authentication Module enables the proxy server to access an LDAP server when performing authorization or authentication routines.
- The WebSphere Transcoding Publisher plug-in allows the proxy server to cache multiple transcoded versions of content for mobile devices when used in conjunction with WebSphere Transcoding Publisher.
You can further extend the functions of Caching Proxy by writing custom plug-in modules to an application programming interface (API). The API is flexible, easy to use, and platform independent. The proxy performs a sequence of steps for each client request it processes. A plug-in application modifies or replaces a step within the request-processing workflow, such as client authentication or request filtering. The powerful Transmogrify interface, for example, provides access to HTTP data and enables substitution or transformation of URLs and Web content. Plug-ins can modify or replace designated processing steps, and you can invoke more than one plug-in for a particular step.