third type of Oracle Application Server
cache, Web Object Cache, is used specifically to support web objects.
Web Object Cache is an HTTP-centric Java object caching service for
servlets and JSP, provided by the OC4J.
We refer to Web Object Cache as HTTP-centric because it typically
uses information from the servlet request object,
, such as the URI, query string, and
cookies, to automatically formulate a name to use for storing and
retrieving objects in a Java Object Cache.
Web Object Cache caching takes place within the OC4J web container before any content produced from a servlet or JSP is sent. Web Object Cache is best used for expensive-to-create or frequently used Java-generated objects. It isn’t a substitute for OracleAS Web Cache, in which rendered content is cached and distributed outside of OC4J. Instead, use OracleAS Web Object Cache only to cache sections of content that need to be merged within an OC4J servlet. Outside OC4J, on the other hand, ESI can be used in OracleAS Web Cache.
A Web Object Cache Java API exists for use in servlets, and a Web Object Cache tag library exists for use in JSPs. A tag library is a set of custom tags that effectively extends the tags available when creating a source file such as an HTML file. These tags are preprocessed by a JSP translator, resulting in a servlet that is then compiled and executed.
Java objects are stored in Web Object Cache using block names. Cache policies determine block naming, ...