Introduction to J2EE

J2EE or Java 2 Platform, Enterprise Edition is one of the most powerful ways of developing Multitiered web applications. The J2EE platform uses a distributed multitiered application model for enterprise applications. Application logic is divided into components according to function, and the various application components that make up a J2EE application are installed on different machines depending on the tier in the multitiered J2EE environment to which the application component belongs. multitiered application can be describes as in the figure below.

As this is about web application development, there is always two sides as Client & Server. In the client side the java pages, html pages are running & in the server side, Java Server Pages (JSP) , Servlets, Enterprise Java Beans (EJB) are running. So tiers made them separate from each other & also give a clear way to communicate each other.

J2EE Containers

The component-based and platform-independent J2EE architecture makes J2EE applications easy to write because business logic is organized into reusable components. In addition, the J2EE server provides underlying services in the form of a container for every component type. Because you do not have to develop these services yourself, you are free to concentrate on solving the business problem at hand.So the container is doing the controlling part of the web components in the web development. Container is the interface between a component & its functional behavior. So in order to execute an application the container should be loaded before hand.
the relationship between container & J2EE can be shown as follows.

There are mainly 5 containers available in J2EE, namely
J2EE Server , Enterprise JavaBeans (EJB) container, Web container, Application client container & Applet container.

Web Service Support

The J2EE platform provides the XML APIs and tools you need to quickly design, develop, test, and deploy web services and clients that fully interoperate with other web services and clients running on Java-based or non-Java-based platforms. Basically J2EE has XML , WSDL , SOAP & UDDI standards support in order to have a complete web service application development environment.

So this is just a brief description of J2EE environment. In the next posts, I'm hoping to tell more about JSP, Servlets & its implementation process in action. Stay tuned until then ;)