After a portlet is invoked and completes generating the output to cache, a cache entry is created containing the output and the side effects of the portlet. These side effects can include calls to other portlets or JavaServer Pages (JSP) files or metadata about the entry, including timeout and entry priority information.
To enable portlet caching see Configuring portlet caching. To configure cache policies for your portlets, see Configuring cacheable objects with the cachespec.xml file.