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# EJB 3.0 JPA Entities

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EJB 3.0 Java Persistence API (JPA) is a specification for persistence in Java EE and SE applications. In JPA, a persistent class is referred to as an entity. An entity is a plain old Java object (POJO) class (see "Plain Old Java Objects (POJO)") that is mapped to the database and configured for usage through JPA using annotations and/or XML.

With JPA, when your application is running inside a container, all of the benefits of the container support and ease of use apply. Note that you can configure the same application to run outside the container.

You can use session beans (see "EJB Session Beans") as the means for your application to interact with JPA.

If you choose to use JPA for your application development, consider the following options:

- TopLink Essentials–the open-source community edition of TopLink. TopLink Essentials is derived from TopLink providing core object-relational mapping functionality necessary for the reference implementation of JPA in EJB 3.0. TopLink Essentials is available in source and binary distributions as the entity-persistence module of GlassFish Open Source Java EE 5 Application Server.

- TopLink–a commercial implementation that provides the preview functionality of JPA.

Both options provide excellent support for this new standard, as well as additional functionality and performance benefits.

For more information, see "Understanding the EJB 3.0 JPA Entity Architecture" and "TopLink Application Architectures".