Managing an Entity Instance’s Life Cycle:

You manage entity instances by invoking operations on the entity by means of an EntityManager instance. Entity instances are in one of four states: new, managed, detached, or removed.

New entity instances have no persistent identity and are not yet associated with a persistence context. Managed entity instances have a persistent identity and are associated with a persistence context.

Detached entity instances have a persistent identify and are not currently associated with a persistence context.
Removed entity instances have a persistent identity, are associated with a persistent context, and are scheduled for removal from the data store.

In this part of Enterprise Session Beans, you will learn how to develop, deploy, and run a simple JPA application named book using stateless session bean. The purpose of ‘book’ is to perform the persistence operations such
as Add record and getting information to or from the database.

The ‘book’ application consists of two enterprise beans, first is BookBank that defines the Table name and Primary key in the database, and second one is BookCatalogBean that performs the Persistence Object Relational Mapping.

There are following steps that you have to follow to develop a ‘book’ JEE application.

1 Create Remote business interface: BookCatalogInterface
2 Implement the Annotated Session Bean: BookCatalogBean
3 Create the Entity bean: BookBank
4 Create the web client: WebClient
5 Deploy book on the server.
6 Run web client on the web browser.

A UML diagram of this application using JPA can be seen as:



Create Remote Business Interface To implement a session bean, we first determine the interface that it exposes. In the Book application, this is a simple Java interface declaring all business methods. package entity.library;

import javax.ejb.Remote;
import java.util.Collection;
@Remote
public interface BookCatalogInterface {
public void addBook(String title, String
author, double price);
public Collection <BookBank>
getAllBooks();
}

II. Implement the annotated session bean

The EJB3 container creates instances of the session bean based on the implementation classes. The application itself never creates session bean instances. It simply asks the