Set up caching in the proxy server

This topic provides information on caching static and dynamic content in the proxy server.

Overview

Procedure

1. Configure the object cache instance for size, disk offload location, and other such capabilities, in the administrative console. Click Servers > Proxy servers > server_name > HTTP proxy server settings > Proxy Cache instance config. Repeat these steps on any nodes that have a proxy server.

2. Select the proxy cache store instance and enable configuration attributes such as cache size, disk offload, and cache replication. For disk offload, IBM recommends that the location be set to a dedicated disk partition.

3. Enable caching at the proxy server, in the administrative console. Click Servers > Proxy servers > server_name > HTTP proxy server settings > Proxy settings page in the administrative console.

4. Select Enable caching and choose a cache instance from the drop-down box.

   1. To enable dynamic content to be cacheable with the proxy server, in the administrative console, click Servers > Proxy servers > server_name > HTTP proxy server settings > Proxy settings, and then select Cache dynamic content. You enable cacheablity and invalidation of dynamic content when you enable servlet caching on the application server, and specifying the cache criteria in a cachespec.xml file that is associated with that application. Invalidations are received by connecting to the cache update URI that is associated with the invalidation servlet hosted on the application server cluster.

      Dynamic content is content that an application, that is hosted on an application server, generates. A proxy server caches dynamic content only if the content is identified as edge cacheable in the cachespec.xml file for the application. All of the information that describes the cache, such as the ID to use for the cache, dependency identifiers for invalidation, and expiration times, is also defined in the cachespec.xml file. Proxy Server uses the ESI protocol to obtain this information from the file.

      See Configuring cacheable objects with the cachespec.xml file for more information on how to set up a cachespec.xml file for an application.

      Cached dynamic content can be invalidated by events in the application server. The ESI Invalidation Servlet, that is contained in the DynacacheEsi.ear application, propagates these invalidation events from the application server to the proxy server. The DynacacheEsi.ear is shipped with WebSphere Application Server and must be deployed in the cluster with the application that is generating the dynamic content for dynamic caching at the proxy server to function properly.

   2. Static caching is enabled by default when caching is enabled for the proxy server. Static content is Web content that is public and accompanied by HTTP response headers, such as EXPIRES and LAST_MODIFIED_TIME, that describe how long the response can be cached. The proxy server uses the HTTP 1.1 RFC (2616), which specifies how content should be treated and includes capabilities such as VARY header support for caching variants of the same resource Uniform Resource Identifier (URI).