Caching Proxy

Caching Proxy reduces bandwidth use and improves a website's speed and reliability by providing a point-of-presence node for one or more back-end content servers. The Caching Proxy can cache and serve static content and content that is dynamically generated by WebSphere® Application Server.

You can configure the Caching Proxy in the role of a reverse proxy server or a forward proxy server, that provides either a point-of-presence access point for an internal or external network server that is responsible for improving request and response time. A reverse proxy server is the default configuration. For more information on reverse and forward configurations, see the documentation about 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 that are stored on web server machines and delivered using the Hypertext Transfer Protocol (HTTP). These web servers are also referred to as origin servers or content hosts. 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 the content 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 function to the proxy server.
  • The Internet caching protocol (ICP) plug-in enables the proxy server to query 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 the integrated authorization or authentication services of Access Manager. .
  • The PAC-LDAP Authentication Module enables the proxy server to access an LDAP server when completing authorization or authentication routines.
  • The WebSphere Transcoding Publisher plug-in enables the proxy server to cache multiple transcoded versions of content for mobile devices when used 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 start more than one plug-in for a particular step.