Based On Of J2ee/ejb The Multi-tier Distributed Architecture Applications

The traditional C/S model has been popular for a long time. Since 1990s, With the application on Internet becoming more and more widely and Internet technology being more and more advanced . The tradition C/S model appears obviously not to meet the development requirement of modern enterprise application. The original computer architecture has developed from the 2-tier C/S architecture to the three-tier/ multi-tier architecture. The three-tier/multi-tier architecture equals to adding a new Logical tier-application tier between client tier and server tier, which makes the business logic separated out from client tier, and then merges storage procedure in database to form application tier. The application tier focus to manage the business logic. Therefore, the multi-tier system must has the following features: distributed, well-scaled, retractable and secure.J2EE platform released by SUN provide standard system framework and services,it not only inherits platform-independent feature of Java language, but also combines component technology. Since J2EE multilayer came out, a big change has happened in software world But J2EE only has the general design pattern, for different specific situation, it's necessary to generate the steady, robust application framework based on J2EE that abstracted from a large number of experience.This paper focuses on the design and realization of EJB-Based multi-tier structure: Three distributed-transact technologies (EJB,CORBA,COM) has been deeply discussed. The Component-Based technology of J2EE framework, EJB, is compared with the other technology in several aspects. At the same time J2EE platform technologies are discussed deeply, such as J2EE platform technologies, communication technologies, EJB component technologies and so on . the design model based on the MVC frame is applied in the J2EE development, so that the separation between the present logic and the business logic in the application is realized. Further more, we discuss an EJB framework with better quality in separating between WEB layer and EJB layer, simplify the normal EJB service. Finally, we propose a system—online office system to demonstrate the above technology.