2.6. Cache Modes

Although technically not part of the API, the mode in which the cache is configured to operate affects the cluster-wide behavior of any put or remove operation, so we'll briefly mention the various modes here.

JBoss Cache modes are denoted by the org.jboss.cache.config.Configuration.CacheMode enumeration. They consist of:

LOCAL - local, non-clustered cache. Local caches don't join a cluster and don't communicate with other caches in a cluster. Therefore their contents don't need to be Serializable; however, we recommend making them Serializable, allowing you the flexibility to change the cache mode at any time.
REPL_SYNC - synchronous replication. Replicated caches replicate all changes to the other caches in the cluster. Synchronous replication means that changes are replicated and the caller blocks until replication acknowledgements are received.
REPL_ASYNC - asynchronous replication. Similar to REPL_SYNC above, replicated caches replicate all changes to the other caches in the cluster. Being asynchronous, the caller does not block until replication acknowledgements are received.
INVALIDATION_SYNC - if a cache is configured for invalidation rather than replication, every time data is changed in a cache other caches in the cluster receive a message informing them that their data is now stale and should be evicted from memory. This reduces replication overhead while still being able to invalidate stale data on remote caches.
INVALIDATION_ASYNC - as above, except this invalidation mode causes invalidation messages to be broadcast asynchronously.