Transactions in enterprise JavaBeans

Like we mentioned earlier in this chapter, by default all EJB methods are automatically wrapped in a transaction. This default behavior is known as container-managed transactions, since transactions are managed by the EJB container. Application developers may also choose to manage transactions themselves, which can be accomplished by using bean-managed transactions. Both of these approaches are discussed in the following sections.

Container-managed transactions

Because EJB methods are transactional by default, we run into an interesting dilemma when an EJB method is invoked from client code that is already in a transaction. How should the EJB container behave? Should it suspend the client transaction, execute its method in a new transaction, and then resume the client transaction? Should it not create a new transaction and execute its method as part of the client transaction? Should it throw an exception?

By default, if an EJB method is invoked by client...