cache Element (Sun Java System Web Server 7.0 Developer's Guide to Java Web Applications)

Sun Java System Web Server 7.0 Developer's Guide to Java Web Applications

This element configures caching for web application components.

The following table describes subelements for the cache element.

Table A–28 cache Subelements


Element	Required	Description
`cache-helper` Element	zero or more	Specifies a custom class that implements the `CacheHelper` interface.
default-helper	zero or one	Allows you to change the properties of the default, built-in `cache-helper` class.
`property` Element	zero or more	Specifies a cache property, which has a name and a value.
`cache-mapping` Element	zero or more	Maps a URL pattern or a servlet name to its cacheability constraints.

The following table describes attributes for the cache element.

Table A–29 cache Attributes


Attribute	Default Value	Description
`max-entries`	`4096`	(Optional) Specifies the maximum number of entries the cache can contain. Must be a positive integer.
`timeout-in-seconds`	30	(Optional) Specifies the maximum amount of time in seconds that an entry can remain in the cache after it is created or refreshed. Can be overridden by a `timeout` element.
`enabled`	`false`	(Optional) Determines whether servlet and JSP caching is enabled. Legal values are `on`, `off`, `yes`, `no`, `1`, `0`, `true`, `false`.

The following table describes properties for the cache element.

Table A–30 cache Properties


Property Name	Default Value	Description
`cacheClassName`	`com.sun.appserv.web` `.cache.LruCache`	Specifies the fully qualified name of the class that implements the cache functionality. For a list of valid values, seeCache Class Names.
`MultiLRUSegmentSize`	`4096`	Specifies the number of entries in a segment of the cache table that should have its own LRU (least recently used) list. Applicable only if `cacheClassName` is set to `com.sun.appserv.web` `.cache.MultiLruCache`.
`MaxSize`	`unlimited; Long.MAX_VALUE`	Specifies an upper bound on the cache memory size in bytes (KB or MB units). Example values are 32 KB or 2 MB. Applicable only if `cacheClassName` is set to `com.sun.appserv.web.` `cache.BoundedMultiLruCache`.

The following table lists possible values of the cacheClassName property.

Table A–31 cacheClassName Values


Value	Description
`com.sun.appserv.web.cache.LruCache`	A bounded cache with an LRU (least recently used) cache replacement policy.
`com.sun.appserv.web.cache.BaseCache`	An unbounded cache suitable if the maximum number of entries is known.
`com.sun.appserv.web.cache.MultiLruCache`	A cache suitable for a large number of entries (>4096). Uses the `MultiLRUSegmentSize` property.
`com.sun.appserv.web.cache.BoundedMultiLruCache`	A cache suitable for limiting the cache size by memory rather than number of entries. Uses the `MaxSize` property.