Linda DeMichiel is Sun Microsystems' specification lead and chief architect for Enterprise JavaBeans 3.0 and the Java Persistence API (JSR 220). In the first segment of this two-part interview, she discusses how the EJB 3 APIs simplify development, how to choose between annotations and XML in configuring an EJB environment, and suggests a practical way to learn about EJB 3.

You can read the interview here:

http://www.artima.com/lejava/articles/refactoring_ejb.html

What do you think of Linda's comments?

one long but useful article,

I use google search find this, Thanks.

Java metadata annotations so developers can use annotations to specify lifecycle callback methods when, and where, such callbacks are useful. Instead of implementing to the interface, just specify what need. That can either be done in a method on the bean class, or you can factor that out of the bean class and place such callbacks on an interceptor class. You don't need to have such callbacks in your main-line code.