Java Technology

The Java EE application development model incorporates Java programming language and the Java virtual machine. The flexibility, portability, security, open-source nature of JEE provides a strong basis for the JEE application model. Java EE has been designed to facilitate development of applications that make enterprise services available for customers.The Java EE application model clearly defines an architecture for implementing services as multi-tier applications that deliver the scalability, accessibility, and manageability needed by enterprise-level applications. The developers can rely on the JEE platform to provide solutions for developing multi-tier services.

The Java EE platform uses a distributed multitiered application model for enterprise applications. Here the approach is to divide application logic into components according to function. These differing component applications are ideally installed as JEE applications in different client machines, catering to varying tier-needs. Under the JEE environment, client-tier components run on the client machine, web-tier components run on the Java EE server, business-tier components run on the Java EE server and enterprise information system (EIS)-tier software runs on the EIS server. Java EE multitiered applications are generally considered to be three-tiered applications because they are distributed over three locations, namely client machines, the Java EE server machine, and the database or legacy machines at the back end.

While other enterprise application tools require platform-specific security measures in each application, the advantage of Java EE security environment lies in the fact that it enables security constraints to be defined at deployment time. The Java EE platform makes applications portable to a wide variety of security implementations by sparing application developers the trouble of implementing security features. The Java EE platform provides standard access control definitions that are defined by the developer and interpreted when the application is deployed on the server. Java EE also provides standard login mechanisms so application developers do not have to implement these mechanisms in their applications.

Java EE applications are made up of components. A Java EE component is a self-contained functional software unit that is assembled into a Java EE application with its related classes and files and that communicates with other components. The Java EE specification defines the Java EE components: application clients and applets are components that run on the client, Java Servlet, Java Server Faces and Java Server Pages(JSP) technology components are web components that run on the server and Enterprise Java Beans (EJB) components are business components that run on the server.

Java EE components are written in the Java programming language and are compiled in the same way as any program in the language. A Java Applet is a small client application written in the Java programming language, getting executed in the Java Virtual Machine installed in the web browser. The client systems will require the Java Plug-in and a security policy file in order for the applet to successfully execute in the web browser. An application client runs on a client machine and provides a way for users to handle tasks that require a richer user interface than can be provided by a markup language. It typically has a graphical user interface (GUI) created from the Swing or the Abstract Window Toolkit (AWT) API. Application clients directly access enterprise beans running in the business tier.

The server and client tiers include components based on the JavaBeans component architecture (JavaBeans components) to manage the data flow between an application client or applet and components running on the Java EE server. Another advantage is that Java EE application uses a thin browser-based client or thick application client.

It must be obvious and clear from the preceding paragraphs, that JEE offers a no-nonsense, developer friendly application development platform. JEE ranks above other peer application development platforms like .NET, in the matter of scalability,flexibility and interoperability. Providing adaptive and seamless architecture for developers, JEE fulfills the need for developing mult-tiered applications and distributed applications,without the complexity of writing individual codes for each set of business applications. JEE has arrived on the scene when developers were feeling the pinch of a reliable development platform. Today JEE has nudged out many other platforms by sheer virtuosity and ease of development.