EJB 面接の質問と回答

Question: What are transaction attributes?

Answer: The transaction attribute specifies how the Container must manage transactions for a method when a client invokes the method via the enterprise bean�s home or component interface or when the method is invoked as the result of the arrival of a JMS message. (Sun�s EJB Specification) Below is a list of transactional attributes:

1. NotSupported - transaction context is unspecified.

2. Required - bean�s method invocation is made within a transactional context. If a client is not associated with a transaction, a new transaction is invoked automatically.

3. Supports - if a transactional context exists, a Container acts like the transaction attribute is Required, else - like NotSupported.

4. RequiresNew - a method is invoked in a new transaction context.

5. Mandatory - if a transactional context exists, a Container acts like the transaction attribute is Required, else it throws a javax.ejb.TransactionRequiredException.

6. Never - a method executes only if no transaction context is specified.