Java Enterprise Edition 5
The Java EE platform hosts enterprise applications, ensuring that they are highly available, reliable, scalable, and secure. Java EE 5 is the latest version of the Java Enterprise Edition platform and is fully supported by Rational Application Developer v7.5.
The Java EE architecture is composed of a set of containers, each of which is a runtime environment that hosts specific Java EE components and provides services to those components.
The Java EE architecture comprises four containers:
- The Enterprise JavaBeans (EJB) container
Hosts EJB components, which are typically used to provide business logic functionality with full transactional support. This container runs on the application server.
- The Web container
Hosts Web components such as servlets and JavaServer Pages, which are executed in response to HTTP requests from a Web client application such as a Web browser. This container runs on the application server.
- The Application Client container
Hosts standard Java applications, with or without a GUI, and provides the services required for those applications to access enterprise components in an EJB container. This container runs on a client machine.
- The Applet container
Hosts Java applets, which are GUI applications that are typically presented by a Web browser. The applet container runs on a client machine under the control of a Web browser.
The Java EE generally includes a database for persistence of enterprise application data. It is not necessary to employ all of the containers in a specific enterprise application. In some enterprise applications, only the Web container is employed. All business logic and persistence functionality executes in the Web container along with the code that presents the user interface. In other enterprise applications, only the Web container and EJB container are employed. The user interface is presented by components in the Web container with all business logic and persistence functionality delegated to the EJB container and the EJB components it contains.
A Java EE enterprise application is assembled from one or more Java EE modules. Java EE modules contain one or more enterprise application components. An optional deployment descriptor, which describes the module and the components that it contains, can also be included in the module. The following sections provide a summary of the purpose served by each of the modules and the types of component typically contained in the module. Subsequent sections describe the types of projects within Application Developer that are used to create each module.
A high level view of the module structure of a Java EE enterprise application...
