Sun Java System Application Server Platform Edition 8.1 2005Q2 Update 2 Developer's Guide

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## cache

Configures caching for web application components.

### Superelements

sun-web-app (`sun-web.xml`)

### Subelements

The following table describes subelements for the `cache` element.

Table A–9 `cache` Subelements

Element | Required | Description
--- | --- | ---
cache-helper | 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 (with attributes) | zero or more | Specifies a cache property, which has a name and a value.
cache-mapping | zero or more | Maps a URL pattern or a servlet name to its cacheability constraints.

### Attributes

The following table describes attributes for the `cache` element.

Table A–10 `cache` Attributes

Attribute | Default | 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` | `true` | (optional) Determines whether servlet and JSP caching is enabled.

### Properties

The following table describes properties for the `cache` element.

Table A–11 `cache` Properties

Property | Default | Description
--- | --- | ---
`cacheClassName` | `com.sun.appserv.web.cache.LruCache` | Specifies the fully qualified name of the class that implements the cache functionality. See Cache Class Names for possible values.
`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`.

### Cache Class Names

The following table lists possible values of the `cacheClassName` property.

Table A–12 `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.

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