Head First EJB

Chapter 9. EJB Transactions: The Atomic Age

Transactions protect you. With transactions, you can take a risk. You can try something BIG, knowing that if anything goes wrong along the way, you can just pretend the whole thing didn’t happen. Everything goes back to the way it was before. The idea is simple—you either commit to everything in the transaction, or you rollback, so that nobody sees what you were trying (but failed) to do. Transactions in EJB are a thing of beauty—you can deploy a bean with customized transaction behavior without touching the bean’s source code! But you can write transaction code, if you need to, so we’ll learn that too.

Objectives

Enterprise Javabeans Transactions

Official:		What it really means:
11.1	Identify correct and incorrect statements or examples about EJB transactions, including bean-managed transaction demarcation, and container-managed transaction demarcation.	You need to know the rules, and implications of, bean-managed (BMT) vs. container-managed (CMT) transaction demarcation. For example, you must know that both message-driven and session beans can use CMT or BMT but entity beans can use only CMT. And message-driven beans and stateless session beans using BMT must end the transaction before the end of the method, but stateful session beans are allowed to keep a transaction open across multiple method invocations from a client. You need to know that ...