When you design an EJB component, you must decide how the bean will manage transaction demarcation: either programmatically in the business methods, or whether the transaction demarcation will be managed by the container based on the value of the transaction attribute in the deployment descriptor.
Session beans and message-driven beans can use either bean-managed transaction demarcation or container-managed transaction demarcation; you cannot create a session bean where some methods use container-managed demarcation and others use bean-managed demarcation. An entity bean must use container-managed transaction demarcation.
When using bean-managed transactions, you must explicitly begin, commit, and roll back new, independent transactions by using the javax.transaction.UserTransaction interface. Transactions begun by the component execute independently of the client’s transaction. If the component has not begun a transaction, the component’s database work is performed independently of any EAServer transaction.
