Research And Design Of J2EE Data Persistence Tier Based On ORM

The structure of traditional application web framework was divided into three tiers, they are presentation tier, business logic tier and infrastructure tier. Business logic tier has two responsibilities at the three tiers structure: business logic and data access. Business logic tier get the data which business logic needed according basic database operation. But it takes a problem that basic logic and database access integrate compactness. For separating the detail of data access from business logic, we can independence the data access tier, so it becomes J2EE five tiers structure. Persistence tier is an important element of J2EE framework. The function of persistence tier is store the data of business state, it accomplish the transfer of application by communicate with other systems.Object-Oriented (00) nowadays is a main technology in computer software development. In the process of software development by 00, relational database (RDBMS) is most popular, so there is a big problem between object model and relational model: impedance mismatch. Impedance mismatch means when the system base on object model store data from relational database, it must face a problem that the description of data not consistent. ORM (object relation mapping) is a technology used to solve the "impedance mismatch" between the relational database and the object model.Based on reading the domestic and overseas literatures, this paper summarizes the research background and significance of the ORM, the domestic and overseas research development, the relative technologies and concepts and so oa By the analysis and comparison of each kind of techniques' characteristic, the research thinking and the technology and method of the realization are put forward. On the basis of dissertating the theory and implement method of object relation mapping, a J2EE persistence tier framework base on semi-automatic ORM which called FacilityORM, is presented. This framework has the function of object relation mapping, so that software engineer can progress data access in manner of object oriented, and pay no attention at the implement of bottom database, it can improve the efficiency of development highly. With an instance, introduce the using method of FacilityORM, and the feasibility of FacilityORM is validated.