Enterprise Bean (EJB) programming tutorials

Enterprise Beans Tutorial

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Enterprise Beans Tutorial

19 RequiresNew If the client is running within a transaction and it invokes the enterprise bean's method, the container takes the following steps: suspends the client's transaction
starts a new transaction
delegates the call to the method
resumes the client's transaction after the method completes If the client is not associated with a transaction, the container starts a new transaction before running the method. You should use the RequiresNew attribute when you want to ensure that the method always runs within a new transaction. Mandatory If the client is running within a transaction and it invokes the enterprise bean's method, the method executes within the client's transaction. If the client is not associated with a transaction, the container throws the TransactionRequiredException.
Use the Mandatory attribute if the enterprise bean's method must use the transaction of the client. NotSupported If the client is running within a transaction and it invokes the enterprise bean's method, the container suspends the client's transaction before invoking the method. After the method has completed, the
container resumes the client's transaction. If the client is not associated with a transaction, the container does not start a new transaction before running the method. Use the NotSupported attribute when you want to ensure that the method will never run within a transaction generated by the container. Supports If the client is running within a transaction and it invokes the enterprise bean's method, the method executes within the client's transaction. If the client is not associated with a transaction, the container does not start a new transaction before running the method. Because the transactional behavior of the method may vary, you should use the Supports attribute with caution. Never If the client is running within a transaction and it invokes the enterprise bean's method, the container throws a RemoteException. If the client is not associated with a transaction, the container does not start a new transaction before running the method. Summary of Transaction Attributes Table 6-1 summarizes the effects of the transaction attributes. Both the T1 and T2 transactions are controlled by
the container. A T1 transaction is associated with the client that calls a method in the enterprise bean. In most
cases, the client is another enterprise bean. A T2 transaction is started by the container just before the method
executes. In the last column, the word "none" means that the business method does not execute within a transaction
controlled by the container. However, the database calls in such a business method might be controlled by the
transaction manager of the DBMS.