NET Platform, Based On The Design Of The O / R Mapping Database Access Middleware Implementation

Database Application System is an application system uses Database Management System to store basic data, and use application programme to implement various business logic by manipulating and analysing those data, which is a recent usual form of systematic software in corporation and government informationization. A data access layer is a basic and indispensable part of a Database Application System. In a few projects of Si Chuan Finance Information Center, we faced many problems of the traditional development process of data access layer, such as code variance, reduplicate work, difficult to transplant, reuse and maintain.In allusion to the development process of information system in middle-sized companies and the above problems, this article designs and implements EasyDAO, which is a data access middleware based on Object/Relational Mapping Technology under .NET platform. This object of EasyDAO is to decrease the workload and make it easier to enhance system functions during development process as well as to run business efficiently and make it easier to maintain and manage system during runtime.This article starts from summarization and analysis of the architecture of Database Application System and methods by which can implement data access layer, introduces and discusses the principle, implementation and strongpoints of Object/Relational Mapping. Based on these theories, this article uses UML techlology, applies proper design patterns to design the work process, main modules, main classes and XML structures of the whole EasyDAO middleware according to the requirments of users. After implementation, EasyDAO is tested both on function and on performance. This article compares the EasyDAO performance to the performance of usual data access method.EasyDAO is composed of two parts: a runtime class library and an assistant construction tool in development. The runtime class lirary gives operation of Object/Relational Mapping and interfaces of data access, transaction management and user defined events. It provides business objects to business logic layer and accelerates access by turning on cache. The assistant construction tool EasyDAOBuilder has two meanings of "construction". One is to construct the EasyDAOProject object from database structure; the other is to construct the entity extensive layer from EasyDAOProject object. EasyDAOBuilder provides a friendly setting and development environment in which users can create project to scan the structure of different-type database, set the properties and check rules of mapping objects, edit SQL statements which are needed in application system. EasyDAOBuilder makes use of CodeDOM and XML technology to generate codes of entity extensive layer and XML mapping files. In addition, it has the ability to scan database changes, which is useful in practical development.The test results illustrate the design of EasyDAO achieves prospective objects. It shows that access database through EasyDAO has similar efficiency as through ADO.NET of .NET platform. And this product do reduce the workload in development and make maintenance more efficient in practical project application At the last part, this article establishes an upgrade plan aiming at the functions and weakness of the current vision EasyDAO.