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Last Resource Commit optimization for JMS

Be Careful

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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.

Maximum one non-XA resource

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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:

and the same example viewed as a Resource Loader configuration

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