The Internet has transformed from a mere publishing medium to an important communication and business facility. Among the many vendors that provide web-based solutions, multi-tiered system architecture became extremely popular. Developing with multiple tiers increases the scalability, performance, and reliability of distributed applications. Server components can be distributed across any number of servers to boost system availability. Rapid modification to these components is possible when business rules or economic conditions dictate. And the location-independence of these components allows system administrators to easily reconfigure system load. The challenge to IT professionals today is to efficiently develop and deploy applications for use on both corporate intranets and over the Internet. Among multi-tiered system architecture, three-tiered client/server architecture provides an environment which supports all of the benefits of both the one-tiered approach and the two-tiered approach while supporting the goals of a flexible architecture.   J2EE The Java 2 Platform, Enterprise Edition is a standard set of Java technologies that streamline the development, deployment, and management of enterprise applications and it is complete in the sense that it is possible to develop a large class of enterprise applications using only the J2EE technologies. J2EE provides the ability to deploy component-based enterprise applications across multiple tiers in a platform natural manner. J2EE Model consists of Client Tier, Business Logic Tier and EIS (Enterprise Information Systems) Tier. We will summarize each tier and their major functionality in the following sections while emphasizing the importance of the abstraction concept. The Model-View-Controller (MVC) application architecture is an abstraction that assists to break an application into logical components for easy architecting processes. In addition, this abstraction minimizes the degree of coupling between the objects. In the MVC architecture, the Model communicates views of changes with the View and provides an ability to access application functionality for the Controller. The View renders the content of a model while maintaining consistency in its presentation when the model changes. The Controller primarily defines application behaviour based on user gestures that will map user actions to model updates. The J2EE platform specifies three categories of technologies: component, service, and communication. The applets, application clients, EJB and Web components are supported by the J2EE platform. One important point to always keep in mind is that applets and application clients run on a client platform where EJB and Web components run on a server platform. J2EE platform services allow components and applications to be customized at deployment time to use available resources in the deployment environment. Naming services (JNDI), deployment services, which consists of Java ARchives (JAR), Enterprise ARchives (EAR) and Web ARchives (WAR), transaction services (JTA), security services are among the major components of the J2EE platform. Communication technologies can be grouped as Internet protocols (TCP/IP, HTTP, SSL, Remote Method Invocation (RMI) protocols like JRMI, Object Management Group Protocols like Java IDL, RMI-IIOP, Messaging technologies like JMS and JavaMail, and finally Data Formats like HTML, image files, JAR file, Class file and XML. back to Development   Trademark Acknowledgements Any company, product or service names are trademarks or service marks of their respective companies.