Mule uses javax.transaction.TransactionManager for managing transaction spanning multiple resources (XA). If you need the SUSPEND semantics for your transactions (i.e. this is what EJB's RequiresNew Tx attribute value does), then you have to use the transaction manager. Contrast this to a more typical javax.transaction.UserTransaction, which is just a thin handle to a transaction manager with limited (though in most cases sufficient) functionality. Particularly, it will not let you suspend the current transaction, otherwise it's merely the same.

Depending on your server, you can run Mule either standalone or embedded in the application server. This is not only your choice, but a requirement for some products, as one server will expose the transaction manager in JNDI, the other will not, and yet another will grant you access only via proprietary APIs. This is unfortunate, but still in line with Java EE 1.4 specification, which does not consider the transaction manager a public API. Thus, you are left to the mercy of your application server vendor.

The following table summarizes some common Java EE servers:

Application Server	Remote	Embedded	Common Location	Lookup class
JBoss			java:/TransactionManager	org.mule.transaction.lookup.JBossTransactionManagerLookupFactory
Weblogic			javax.transaction.TransactionManager	org.mule.transaction.lookup.WeblogicTransactionManagerLookupFactory
WebSphere			Proprietary API call	org.mule.transaction.lookup.WebsphereTransactionManagerLookupFactory
Resin			java:comp/TransactionManager	org.mule.transaction.lookup.Resin3TransactionManagerLookupFactory
JRun			java:/TransactionManager	org.mule.transaction.lookup.JRunTransactionManagerLookupFactory
Other			specified via a jndiName property	org.mule.transaction.lookup.GenericTransactionManagerLookupFactory

E.g. to use Weblogic's transaction manager:

<transaction-manager factory="org.mule.transaction.lookup.WeblogicTransactionManagerLookupFactory" />