Head First EJB

Chapter 5. Entity Bean Intro: Entities are Persistent

Entity beans persist. Entity beans exist. Entity beans are. They are object representations of something in an underlying persistent store. (Think: database, because most entity beans represent something from a relational database.) If you have a Customer entity bean, then one bean might represent the entity Tyler Durden, ID #343, while another is the entity Donny Darko, ID #42. Two beans, representing two real entities. An entity bean is simply a realization of something that already exists in a persistent store. Something that already is. And these suckers are hard to kill! As long as the data is in the database, it can keep coming back in the form of an entity bean.

Objectives

Entity Beans

Official:		What it really means:
5.1	Identify correct and incorrect statements or examples about the client view of an entity bean’s local and Remote home interface, including the code used to locate an entity bean’s home interface, and the home interface methods provided to the client.	You have to know the rules for an entity bean home interface, and especially how they’re different from a session bean. You must know that you’re not required to have a create() method, but that you must have at least one finder method, findByPrimaryKey(). You have to know that the return type of single-entity finders and create methods must always be the component ...