11.2. JTA Support
JBoss Cache can be configured to use and participate in JTA compliant transactions. Alternatively, if transaction support is disabled, it is equivalent to using autocommit in JDBC calls, where modifications are potentially replicated after every change (if replication is enabled).
What JBoss Cache does on every incoming call is:
- Retrieve the current
javax.transaction.Transaction
associated with the thread - If not already done, register a
javax.transaction.Synchronization
with the transaction manager to be notified when a transaction commits or is rolled back.
In order to do this, the cache has to be provided with a reference to environment's
javax.transaction.TransactionManager
. This is usually done by configuring the cache with the class name of an implementation of the TransactionManagerLookup
interface. When the cache starts, it will create an instance of this class and invoke its getTransactionManager()
method, which returns a reference to the TransactionManager
.
JBoss Cache ships with
JBossTransactionManagerLookup
and GenericTransactionManagerLookup
. The JBossTransactionManagerLookup
is able to bind to a running EAP instance and retrieve a TransactionManager
while the GenericTransactionManagerLookup
is able to bind to most popular Java EE application servers and provide the same functionality. A dummy implementation - DummyTransactionManagerLookup
- is also provided for unit tests. Being a dummy, this is not recommended for production use a it has some severe limitations to do with concurrent transactions and recovery.
An alternative to configuring a
TransactionManagerLookup
is to programmatically inject a reference to the TransactionManager
into the Configuration
object's RuntimeConfig
element:
TransactionManager tm = getTransactionManager(); // magic method cache.getConfiguration().getRuntimeConfig().setTransactionManager(tm);
Injecting the
TransactionManager
is the recommended approach when the Configuration
is built by some sort of IOC container that already has a reference to the TransactionManager
.
When the transaction commits, we initiate either a one-phase or two-phase commit protocol. See Section 8.1.2.1, “Replicated Caches and Transactions” for details.