What is Java Enterprise Edition, today, in 2007? Java EE is many specifications that are implemented by an application server such as: Servlets, Java Server Pages (JSP), JSP Standard Tag Library (JSTL), Java Server Faces (JSF), EJB Stateless Stateful Session Beans, Java Messaging Service (JMS), Message Driven Beans (MDB), EJB Timer Service, Java Persistence Architecture (JPA), Java Connector Architecture (JCA), Java Mail, Java Naming Directory Interface (JNDI), Java API for XML Web Services (JAX-WS), Java Transaction API (JTA), Java Authentication and Authorization Service (JAAS), and I\'m sure there\'s more. Because all of these technologies are built-into the application server, you do not need to include 20-40 MB of JAR files in your project deployments; each with different license restrictions.
Many of these specifications have been around for a long time and improve slowly every few years. For example, EJB 3.0 from Java EE 5 has greatly improved usability based on lessons learned from Spring. Still, some argue that EJB 3.0 has not matched the full functionality of Spring beans.
Other technologies were new in Java EE 5 such as Java Persistence Architecture and Java Server Faces. Even though JPA\'s design was based on Hibernate, some argue that JPA has not matched Hibernate\'s full functionality. JSF is also missing a few things. The open source world has filled those gaps by building frameworks on top of it such as: Sun Creator Studio/Visual Web Pack, Jboss Seam, and Apache Shale.
Despite these slight imperfections, Java EE 5 was a giant leap forward and created a solid foundation to build upon. Now that the foundation is laid, the Java Community Process (JCP) committees have been able to focus on the types of things they didn\'t have time for in Java EE 5. Lets have a look at what they\'ve been working on:
Note: The following information is mostly copy/pasted from various Power Point slides available from JavaOne\'s website. Since Java EE 6 is not final, any of the following information may change.
Enterprise Java Beans 3.1 Local business interfaces are optional. Develop local EJB components using only a bean class. Client still never uses new() to obtain a reference. There is still separation between client reference objects and bean instances which enables the container to inject value added features such as: pooling of stateless session bean instances, activation/passivation of stateful session beans, lazy initialization, transparent clustering, concurrency control. Reference is of type bean class but client contract only exposes the EJB component\'s public Local business methods. Local client programming model essentially the same with/without Local business interface.本文链接： http://rsonlinevendor.immuno-online.com/view-691251.html
