BMT is a model that performs transaction management in an Enterprise Bean. The BMT target is the Session Beans and the Message-driven Beans (BMT does not target the Entity Beans, the CMT target is always Entity Beans).

During BMT, use javax.transaction.UserTransaction in the business methods of the Enterprise Bean and perform the following operations:

1. Start the transaction
2. Update the resource manager
3. Commit or roll back the transaction

In a Stateless Session Bean, one transaction needs to be concluded (committed or rolled back) in one business method. In a Message-driven Bean, a transaction needs to be concluded (committed or rolled back) in one of the following methods: The methods differ depending on the versions of EJB.

• onMessage method (for EJB 2.0)
• Method of any message listener (for EJB 2.1 or later versions)

On the other hand, in a Stateful Session Bean, many business methods can be included in a single transaction scope. At this point, the EJB container maintains the relationship between the Bean instance and the transaction. The following figure shows the Stateful Session Bean in BMT:

Figure 2-6 Stateful Session Bean in BMT

Table 2-17 Transaction control in BMT

Client-side transactions	Transactions of Bean instance	Transactions connected to the methods
--	--	--
T1	--	--
--	T2	T2
T1	T2	T2

Legend:

--: Either a transaction is not started or is not mapped

T1: Transaction started in the client

T2: Transaction started in the Bean

Note

If a transaction is not concluded and a new transaction is started by using the UserTransaction.begin method, the EJB container throws javax.transaction.NotSupportedException.