Enterprise JavaBeans, Third Edition

Nontransactional Beans

Beans that reside outside a transaction scope normally provide some kind of stateless service that does not directly manipulate data in a data store. While these types of enterprise beans may be necessary as utilities during a transaction, they do not need to meet the stringent ACID requirements of a transaction.

Consider a nontransactional stateless session bean, the Quote EJB, that provides live stock quotes. This EJB may respond to a request from a transactional EJB involved in a stock purchase transaction. The success or failure of the stock purchase, as a transaction, will not impact the state or operations of the Quote EJB, so it does not need to be part of the transaction. Beans that are involved in transactions are subjected to the isolated ACID property, which means that their services cannot be shared during the life of the transaction. Making an enterprise bean transactional can be an expensive runtime activity. Declaring an EJB to be nontransactional (i.e., NotSupported) leaves it out of the transaction scope, which may improve the performance and availability of that service.