This is the second of four installments that make up Chapter 4: Introduction to EJBs from the book Sams Teach Yourself J2EE in 21 Days (ISBN:0-672-32384-2) written by Martin Bond, Dan Haywood, Debbie Law, Andy Longshaw, and Peter Roxburgh, published by Sams Publishing.
What's in an EJB?
So far, you have been presented with a "black box" view of an EJB;
it provides business functionality via an RMI remote interface, and it
cooperates with its container to perform its duties. To understand, use, and
ultimately write EJBs, you will need to know more in concrete terms about the
Java programming artefacts that make up an EJB. In other words, what's in
one?
The Business Interface
The primary purpose of an EJB is to deliver business or application logic. To
this end, the bean developer will define or derive the business operations
required of the bean and will formalize them in an RMI remote interface. This is
referred to as the bean's business or remote interface as opposed to the
home interface you will look at in a moment.
