Java EE

What is it?

The Java Platform, Enterprise Edition, or Java EE, formerly known as J2EE, is a platform for Java-based enterprise computing. It encompasses several technologies.

• JNDI (Java Naming and Directory Interface)
• JMS (Java Message Service)
• Servlets and Java Server Pages
• Web Services Support
  • SAAJ (SOAP with Attachments API for Java)
  • JAX-RPC (Java API for XML-based RPC)
  • JAXR (Java API for XML Registries)
  • JAXB (Java Architecture for XML Binding)
• JDBC (Java Database Connectivity)
• JCA (Java Connector Architecture)
• JTA (Java Transaction Architecture)
• JTS (Java Transaction Service)
• JAAS (Java Authentication and Authorization Service)
• JACC (Java Authorization Contract for Containers)
• JMX (Java Management Extensions)
• JavaMail
• EJB (Enterprise Java Beans)

Related technologies not officially part of the platform, but probably used with it

• JSTL (standard tag library for JSP pages)
• JSF (Java Server Faces)
• JDO (Java Data Objects)
• JNLP
• Portlets
• JWSDL

History

• J2EE 1.2 (December 1999)
• J2EE 1.3 (September 2001)
• J2EE 1.4 (November 2003)
• Java EE 5 (soon)

Links

• Sun's Java EE Main Page
• J2EE 1.4 Tutorial
• J2EE 1.4 Specification
• Java EE 5 Specification
• J2EE Web Services Main Page

Structure of a Java EE Application

Sun's documentation (see, e.g. Chapter 1 of the J2EE 1.4 Tutorial) show enterprise applications consisting of web components and EJB components:

The Java EE Server provides: JNDI, authentication, HTTP (it has an embedded web server), deployment and management functionality.

The EJB container portion of the Java EE server provides: transaction management, security, remote connectivity, lifecycle management, and database connection pooling.

But these days, there is a lot of momentum behind writing Java EE applications without EJBs. Many developers write the entire enterprise application in the .war file only. The nice features of EJBs can be picked up by other frameworks, such as Spring or Hibernate.

Servlets and Java Server Pages

See this page.

Web Services Support

SAAJ

Very low level, implemented in javax.xml.soap.

JAX-RPC

Higher-level, built on top of SAAJ. Used by most developers.

JAXR

In packages javax.xml.registry and javax.xml.registry.infomodel

JMS

JCA

Manages connections, security, transactions, lifecycle, work, messages(?)

JACC

javax.security.jacc