Design And Implementation Of J2EE Persistence Tier Based On ORM

Traditional Web application can be divided into three tiers: presentation tier, business logic tier and data tier. In the absence of Framework, the Web application development process tends to be more chaotic mixed with various codes. The famous J2EE framework does much to the process of developing to the web application. Programmers may dislike it for its complexity or its poor performance for migration, but they master its design pattern perfectly. Many new Frameworks were born, which promote some excellent solution to the special problems. The Frameworks are based on the J2EE core design theory. The Struts has resolved the problem for the code rules and the design pattern about the presentation tier and business logic tier. The Spring manages the business entities and the data entities perfectly. The Hibernate realizes the ORM very well. It makes the business entities can access the database effect.Persistence tier manages the operation to the databases very well in a J2EE project. There are many good persistence products in the market. The most famous one should be the Hibernate. It can promote some perfect solutions for the persistence tier design with the ORM theory. It provides "objectized" interface and promotes a new design pattern for the cooperation between database and object. The Hibernate gives us many better choices for the common operation. The performance of the software gets a promotion because of the Hibernate. But the Hibernate may be a little bigger for the project which is not big. What the small projects need is some simple support such as convenient interface and some simple optimization for the performance. According to this, the author tries to design and implement a simple J2EE tier with the ORM theory and the experience of the practice projects - SDA (Simple Data Architecture).The design and the implementation of this SDA are based on the ORM theory. The primary target is to provide some simple "objectized" interface and optimization for the performance. It's very small, but it may provide the core function set. SDA is a simple, flexible persistence tier; apply to small and medium-scale projects. Some small projects can import it as a part of the project itself. SDA can also be embedded in other Framework systems.The process of the design and implementation is divided into the steps as follows: feasibility validation, function design, detail design and the codeimplementation. Firstly, the paper describes the basic principles of J2EE and ORM, the theoretical basis for SDA, as well as the design principle for SDA. Then, the paper discusses the design and implementation process of SDA in detail. Finally, the paper proposes some typical cases, which verify the correctness and validity of SDA.The paper successfully finishes the design and implementation of the basic functions of SDA. Further improve of SDA is also been noted.