EclipseLink JPA Persistence
The Java Persistence API ( JPA ) is a component of EJB 3.0 and replaces CMP and
JDO. Oracle's strategic Java persistence implementation within Oracle Fusion
Middleware 11 g is Oracle TopLink 11 g , which is based on the open source
EclipseLink. EclipseLink is based on an older version of TopLink, which Oracle
contributed to Eclipse. The EclipseLink version in Oracle Fusion Middleware
11 g supports the JPA 1.0 specification. In this chapter, we shall discuss the JPA
framework and the EclipseLink JPA persistence provider.
What is a JPA persistence provider? A JPA persistence provider is an implementation
of the JPA; JPA is just a specification. Various JPA persistence providers such
as Hibernate, Apache OpenJPA, and JPA for WebSphere Application Server are
available, but we shall be discussing the persistence provider in Oracle Fusion
Middleware: the EclipseLink JPA persistence provider. This section is not meant to
be a repetition of the JPA specification ( http://jcp.org/en/jsr/detail?id=220 ),
or the EclipseLink JPA documentation ( http://wiki.eclipse.org/Category:JPA ),
but a primer and an introduction to some of the features/values used in this topic. In
this chapter, we shall discuss the following:
• How to specify the EclipseLink persistence provider?
• The JPA framework
° The advantages of JPA
° What is required for JPA?
• Types of Entity Managers
° Container-managed entity manager
° Application-managed entity manager