Java Reference
In-Depth Information
Finally, Enterprise JavaBeans can now be packaged inside a
Web ARchive
(
WAR
)
file. This feature greatly simplifies EJB packaging, as in the past an
Enterprise
ARchive
(
EAR
) file was needed to package web functionality and EJB functionality
into a single module.
Java Persistence API (JPA) 2.0
JPA was introduced as a standard part of Java EE in Version 5 of the specification.
JPA was intended to replace entity beans as the standard object-relational mapping
framework for Java EE. JPA adopted ideas from third-party object-relational frame-
works such as Hibernate and JDO and made them part of the standard.
JPA 2.0 improves on JPA 1.0 in a number of areas:
• It provides transparent support for bean validation (JSR-303)
• It provides enhanced collection support with the introduction of the
@Ele-
mentCollection
and
@OrderColumn
annotations
• JPA queries can now be built through the new Criteria API, reducing the
reliance on JPQL
• The
JPA Query Language
(
JPQL
) has improved; it allows adding sup-
port for SQL-like CASE expressions, and NULLIF and COALESCE oper-
ators
Contexts and Dependency Injection for Java
Contexts and Dependency Injection
(
CDI
) (JSR 299) defines a set of services for
the Java EE environment that makes applications much easier to develop. CDI lever-
ages a simpler integration between the Web (JSF) and business logic (EJB) tiers,
resulting in a significantly simplified programming model for web-based applications;
it also provides a programming model suitable for rapid development of simple, data-
driven applications. This is a domain where Java EE has been perceived as overly
complex in the past.
Java Servlet API 3.0
Java Servlets API 3.0 provides easier web application development with enhanced
annotations and integrated Web 2.0 programming model support, security enhance-
