Caching Features

The Application Server has the following web application response caching capabilities:

• Caching is configurable based on the servlet name or the URI.

• When caching is based on the URI, this includes user specified parameters in the query string. For example, a response from /garden/catalog?category=roses is different from a response from /garden/catalog?category=lilies. These responses are stored under different keys in the cache.

• Cache size, entry timeout, and other caching behaviors are configurable.

• Entry timeout is measured from the time an entry is created or refreshed. To override this timeout for an individual cache mapping, specify the cache-mapping subelement timeout.

• To determine caching criteria programmatically, write a class that implements the com.sun.appserv.web.cache.CacheHelper interface. For example, if only a servlet knows when a back end data source was last modified, you can write a helper class to retrieve the last modified timestamp from the data source and decide whether to cache the response based on that timestamp.

• To determine cache key generation programmatically, write a class that implements the com.sun.appserv.web.cache.CacheKeyGenerator interface. See CacheKeyGenerator Interface.

• All non-ASCII request parameter values specified in cache key elements must be URL encoded. The caching subsystem attempts to match the raw parameter values in the request query string.

• Since newly updated classes impact what gets cached, the web container clears the cache during dynamic deployment or reloading of classes.

• The following HttpServletRequest request attributes are exposed:

  • com.sun.appserv.web.cachedServletName, the cached servlet target

  • com.sun.appserv.web.cachedURLPattern, the URL pattern being cached

• Results produced by resources that are the target of a RequestDispatcher.include() or RequestDispatcher.forward() call are cached if caching has been enabled for those resources. For details, see the descriptions of the cache-mapping and dispatcher elements in the sun-web.xml file.