Java Reference
In-Depth Information
What's New in EJB 3.0
The main objective of the
Enterprise
JavaBeans
(
EJB
) 3.0 specification is to improve
the EJB architecture by reducing its complexity from the developer's point of view.
EJB 3.0 has simplified the development of EJBs with the introduction of some new
features. The new features include support for metadata annotations, default values
for a configuration, simplified access of environmental dependencies and external
resources, simplified session and entity beans, interceptors, enhanced support for
checked exceptions, and elimination of callback interfaces. The persistence and
object/relational model has been revised and enhanced in EJB 3.0. The persistence
and object/relational model in EJB 3.0 is the
Java
Persistence
API
(
JPA
). We shall
discuss and introduce these new features in this chapter.
Metadata annotations
Metadata annotations were introduced in JDK 5.0 as a means to provide data about
an application. Annotations are used for the following purposes:
• Generating boilerplate code (code that is repeated in different sections of a
Java program) automatically.
• Replacing coniguration information in coniguration iles such as
deployment descriptors.
• Replacing comments in a program.
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