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Comment: Migrated to Confluence 5.3

Last Resource Commit optimization for JMS

This feature appeared in BTM 1.3.3 and is not available in earlier versions.

Note
titleBe Careful

There is one caveat with Last Resource Commit. There is a small chance that a transaction ends up with inconsistent results across participating resources if BTM crashes while a transaction is in-flight. The chance is small but it exists so be careful when using that feature. This is in no way a limitation of BTM but of the concept itself.

Please note that if you only intend to run transactions against a single JMS server using Last Resource Commit this scenario is 100% safe, otherwise not.

In theory, only JMS servers supporting XA and providing a javax.jms.XAConnectionFactory implementation can be used with transaction managers. In practice, there is a way around this limitation.

The Last Resource Commit optimization (sometimes referred to as Last Resource Gambit or Last Agent optimization) allows a single non-XA resource (JMS server or database) to participate in a XA transaction by cleverly ordering the resources.

Info
titleMaximum one non-XA resource

There can be at most one resource emulating XA with Last Resource Commit participating in a transaction. If it happens that you're trying to use a second emulating resource while one has already been used, BTM will throw an exception. Again, this is not a limitation of BTM but of the concept itself.

To enable it, you just have to create a PoolingConnectionFactory using the bitronix.tm.resource.jms.lrc.LrcXAConnectionFactory as the XAConnectionFactory implementation.

Here's an example of code configuring a ActiveMQ datasource:

Code Block
PoolingConnectionFactory myConnectionFactory = new PoolingConnectionFactory();
myConnectionFactory.setClassName("bitronix.tm.resource.jms.lrc.LrcXAConnectionFactory");
myConnectionFactory.setUniqueName("amq-lrc");
myConnectionFactory.setMaxPoolSize(5);
myConnectionFactory.getDriverProperties().setProperty("connectionFactoryClassName", "org.apache.activemq.ActiveMQConnectionFactory");
myConnectionFactory.getDriverProperties().setProperty("properties.brokerUrl", "tcp://localhost:61616");

and the same example viewed as a Resource Loader configuration

Code Block
resource.ds.className=bitronix.tm.resource.jms.lrc.LrcXAConnectionFactory
resource.ds.uniqueName=amq-lrc
resource.ds.maxPoolSize=5
resource.ds.driverProperties.connectionFactoryClassName=org.apache.activemq.ActiveMQConnectionFactory
resource.ds.driverProperties.properties.brokerUrl=tcp://localhost:61616