The container for a distributable web application makes use of JBoss Cache to provide HTTP session replication services around the cluster. The container integrates with the
CacheManager service to obtain a reference to a JBoss Cache instance (see Section 17.1.3.1, “The JBoss Enterprise Web Platform CacheManager Service”).
The name of the JBoss Cache configuration to use is controlled by the
cacheName element in the application's jboss-web.xml (see Section 21.2.1, “Enabling session replication in your application”). In most cases, though, this does not need to be set as the default values of standard-session-cache and field-granularity-session-cache (for applications configured for FIELD granularity) are appropriate.
The JBoss Cache configurations in the
CacheManager service expose a number of options. See Chapter 24, JBoss Cache Configuration and Deployment and the JBoss Cache documentation for a more complete discussion. The standard-session-cache and field-granularity-session-cache configurations are already optimized for the web session replication use case, and most of the settings should not be altered. Administrators may be interested in altering the following settings:
cacheMode- The default is
REPL_ASYNC, which specifies that a session replication message sent to the cluster does not wait for responses from other cluster nodes confirming that the message has been received and processed. The alternative mode,REPL_SYNC, offers a greater degree of confirmation that session state has been received, but reduces performance significantly. See Section 24.1.2, “Cache Mode” for further details. enabled(inbuddyReplicationConfig)numBuddies(inbuddyReplicationConfig)- Set to a value greater than the default (
1) to increase the number of backup nodes onto which sessions are replicated. Only relevant if buddy replication is enabled. See Section 24.1.8, “Buddy Replication”. buddyPoolName(inbuddyReplicationConfig)- A way to specify a preferred replication group when buddy replication is enabled. JBoss Cache tries to pick a buddy who shares the same pool name (falling back to other buddies if not available). Only relevant if buddy replication is enabled. See Section 24.1.8, “Buddy Replication”.
multiplexerStack- Name of the JGroups protocol stack the cache should use. See Section 17.1.1, “The Channel Factory Service”.
clusterName- Specifies the name JGroups will use for this cache's channel. Only change this if you create a new cache configuration, in which case this property should have a different value from all other cache configurations.
If you wish to use a completely new JBoss Cache configuration rather than editing one of the existing ones, please see Section 24.2.1, “Deployment Via the CacheManager Service”.