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## com.bea.p13n.cache.spi
Class CacheProvider

    java.lang.Object
      com.bea.p13n.cache.spi.CacheProvider

Direct Known Subclasses:
  P13nCacheProvider

    public abstract class CacheProvider

extends Object

Service-provider class for `Cache` implementations.

A Cache provider is a concrete subclass of this class that has a public no- argument constructor and implements the abstract methods specified below.

A CacheProvider implementer should generally package their provider in a jar. That jar should consist of any necessary classes (including, of course, an implementation of CacheProvider), as well as a file named `META-INF/services/com.bea.p13n.cache.spi.CacheProvider`. That services file should contain one or more class names, one per line, each of which should be a concrete CacheProvider implementation.

The provider jar(s) should then be deployed with the application by including the jar in the application's `APP-INF/lib` directory. Provider jars may also be included in the system classpath, although this changes the scoping of the provider class objects, and causes the provider implementations to be shared by multiple applications. It is suggested that provider implementors specify to their customers if such a configuration is suggested or supported.

On initialization, the `CacheFactory` will load all such providers, and additionally choose one provider to be the default. The default is set by the application's configuration or by a system property. Additionally, each named cache may choose a specific provider. See the following CacheFactory methods for further description of this: `CacheFactory.getCacheProvider(String)`, `CacheFactory.getDefaultProviderId()`, and `CacheFactory.getCache(String)`.

Implementations of the abstract methods of this class must be safe for use by multiple concurrent threads.

Configure caches to use the provider using the application's `META-INF/p13n-cache-config.xml` descriptor. Set the `provider-id` element on a set of caches, and/or use the `default-provider-id`.

Constructor Summary
`CacheProvider()` Default constructor.

Method Summary
`void` | `flushCache(String cacheName, Object key)` Clear all clustered replicas of the Cache with the given name.
`void` | `flushKeys(String cacheName, IKeySelector keySelector)` Flush the keys indicated by `IKeySelector` in the local cache and any cluster cache that may exist.
`abstract Cache` | `getCache(String cacheName, CacheConfig config)` Return a `Cache` implementation with the given name.
`abstract String` | `getProviderId()` Name or identity of this provider.
`protected String` | `getScopeIdentifier()` Return a scope identifier that may be used by the CacheProvider to scope the Cache implementations returned by the CacheProvider.
`abstract String` | `getVendorInfo()` Returns the name of the organization, vendor, or company that provided this implementation.
`abstract String` | `getVersionString()` Return the version of this Cache provider implementation.
`void` | `init()` Initialize the CacheProvider.
`void` | `release()` Release all local resources associated with the CacheProvider.
`void` | `releaseCache(Cache cache)` Release all local resources associated with the specified Cache instance.
`String` | `toString()` Return a human readable String representation of this CacheProvider.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### CacheProvider

    public CacheProvider()

  Default constructor.

Method Detail

### init

    public void init()

  Initialize the CacheProvider. This method is called immediately after instantiation and before the provider is used.

  This default implementation does nothing.

### release

    public void release()

  Release all local resources associated with the CacheProvider.

  The CacheFactory will call this method after the J2EE application for which this CacheProvider is providing Cache implementations is shutdown.

  Releasing a CacheProvider makes it no longer usable; any attempt to use the CacheProvider may result in an exception.

  This default implementation does nothing.

### getCache

    public abstract Cache getCache(String cacheName,
                                   CacheConfig config)

  Return a `Cache` implementation with the given name.

  It is the responsibility of the CacheProvider to perform any Cache configuration before returning the Cache instance from this method. The Cache configuration mechanism is assumed to be vendor specific, however the CacheConfig object supplied in the method may be used to obtain suggested Cache configuration properties. This CacheConfig will be constructed from the p13n-cache-config.xml, if the cache is configured there.

  Parameters
    `cacheName` - the name of the Cache to return
    `config` - suggested Cache configuration that may be used by the CacheProvider to configure the returned Cache; this may be ignored by the CacheProvider
  Returns
    a Cache instance identified by the given name

### flushCache

    public void flushCache(String cacheName,
                           Object key)

  Clear all clustered replicas of the Cache with the given name.

  This default implementation will use multicast to broadcast a flush signal to all peer nodes of the WebLogic cluster. Upon receipt of this signal, the instance of that cache will call either `Cache.remove(Object)` with the key, or `Cache.clear()` if key is null.

  Providers with other flushing strategies should override this method without calling `super.flushCache()`.

  Parameters
    `cacheName` - the name of the Cache to flush
    `key` - an optional key; if not null, only the entry with the given key should be removed from all clustered replicas

### releaseCache

    public void releaseCache(Cache cache)

  Release all local resources associated with the specified Cache instance.

  Releasing a Cache reference makes it no longer usable; any attempt to use the reference may result in an exception.

  This default implementation simply calls `Cache.clear()`

  Providers with other strategies should override this method without calling `super.releaseCache()`.

  Parameters
    `cache` - the Cache to release

### getProviderId

    public abstract String getProviderId()

  Name or identity of this provider. This is used to uniquely identify a provider during configuration. It is suggested that this id be based on the vendor package namespace, such as "com.bea.p13n" (which is the name of the default P13nCacheProvider).

  Returns
    the provider id

### getVendorInfo

    public abstract String getVendorInfo()

  Returns the name of the organization, vendor, or company that provided this implementation.

  Returns
    the name of the vendor that implemented this Cache provider

### getVersionString

    public abstract String getVersionString()

  Return the version of this Cache provider implementation.

  Returns
    the version

### getScopeIdentifier

    protected final String getScopeIdentifier()

  Return a scope identifier that may be used by the CacheProvider to scope the Cache implementations returned by the CacheProvider. Its use is not required. It is provided for those providers which may need some scoping hint from the server.

  When used within a J2EE application, this scope identifier is the application name. When used outside an application context (i.e J2SE), this will be null.

  One approach to scoping Cache implementation would be to fully qualify the cache name by append the scope identifier to the name passed to the `getCache(String, CacheConfig)` method.

  Returns
    the name of the cache provider's scope (usually an application name). May be null.

### toString

    public String toString()

  Return a human readable String representation of this CacheProvider.

  Overrides:
    `toString` in class `Object`
  Returns
    a String representation of this object.

### flushKeys

    public void flushKeys(String cacheName,
                          IKeySelector keySelector)

  Flush the keys indicated by `IKeySelector` in the local cache and any cluster cache that may exist. An implementation of the `CacheProvider` interface should override the default implementation of this method.

  The default implementation will use multicast to broadcast a flush signal to all peer nodes of the WebLogic cluster. Upon receipt of this signal, the instance of that cache will call either `Cache.remove(Object)` with the key, or `Cache.clear()` if key is null.

  Parameters
    `cacheName` - the name of the cache to be flushed
    `keySelector` - the set of keys to be flushed

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