About Cache Population Oracle Fusion Middleware Online Documentation Library

Caching and Compressing Content 6-3 You configure a caching rule by specifying caching attributes based on the URL or the Content-Type response header with Fusion Middleware Control, or you set the caching attributes for a specific object within a Surrogate-Control response-header field. Those objects matching the rule are not cached until there is a client request for them. Oracle Web Cache uses the following priority to determine object cacheability: 1. Surrogate-Control response header 2. Caching rule configured with Fusion Middleware Control 3. Other HTTP headers: ■ Authorization request header ■ Proxy-Authorization request header ■ Pragma: no-cache response header ■ Warning response header If any of these headers are present, then Oracle Web Cache does not cache the object. 4. Cookie values from Cookie request header and Set-Cookie response header 5. Cache-Control response header 6. Expires response header The Surrogate-Control response-header field enables the origin server to override the caching rules configured through Fusion Middleware Control. When both a Surrogate-Control response header and a caching rule for the same object are present, Oracle Web Cache merges the two. For example, if there is a caching rule for an non-cacheable object set in Fusion Middleware Control with compression enabled, and the response header contains Surrogate-Control: max-age=30+60, then Oracle Web Cache respects both settings. Oracle Web Cache uses the max-age control directive from the Surrogate-Control response-header to cache the object and the compression setting from the caching rule. If there is a conflict between the Surrogate-Control response header and a caching rule, then Oracle Web Cache uses the settings from the Surrogate-Control response header. If no caching rules or the Surrogate-Control response header are specified, then Oracle Web Cache behaves just as HTTP proxy cache does, that is, it relies on HTTP header information to determine what is cacheable. Generally, HTTP proxy caches store only pages with static content. For a description of how Oracle Web Cache determines cache population, see Section 6.1 . Notes: ■ You can pre-populate the cache using Web crawler freeware such as WGET to warm up the cache on restart or after bulk invalidation operations. See http:www.gnu.orgsoftwarewgetwget.html for further information about WGET. ■ When you stop Oracle Web Cache, all objects are cleared from the cache. In addition, all statistics are cleared.