Research And Application Of Object/Relational Mapping Based On.NET Framework

Almost all the software development of enterprise applications involves operations of data access and update. Most present solutions use relational databases to preserve data and use object-oriented method for enterprise applications domain modeling. But it takes us much time and energy to transform data between object-oriented model and relational model, because of the contradiction between them. In order to settle that problem, it is more effective to construct a persistence layer based on Object/Relational Mapping in n-tier enterprise applications.This paper researches lightweight persistence layer framework based on Object/Relational Mapping, provides solutions for key problems and implements the persistence layer framework in project based on that. The major work of this paper includes:1. Having analyzed the theoretics of object model, relational model and Object/Relational Mapping, it proposes a lightweight architecture of persistence layer framework based on Object/Relational Mapping, and provides the design of it. In view of the deficiency of current persistence layer for applications of small and medium-sized enterprises in .NET platform like complexity in technique, bulkiness in architecture, inconvenience in study and use, it provides a more convenient manner to use, simplifies the mechanism of mapping, enhances the efficiency of system, reduces the coupling of persistence layer.2. It analyzes the key problems in design of persistence layer and provides corresponding solutions. The framework adopts object broker in singleton pattern to implement data access, effectively enhances the efficiency of connection; designs a specially class hierarchy to implement multi-objects processing according to conditions; provides supports to SQL and store procedures for performance; encapsulates different databases to isolate the differences of them; provides a more flexible management of transaction for different requirement and timestamp for concurrent problems; adopts cursor, proxy and cache image to optimize system performance; uses XML files to map classes and databases for the convenience of modification and maintenance.3. According to the theory of object-oriented software engineering, it implements the persistence layer framework in Project Management System of Zhenjiang Water Industry Parent Company using UML and C#, and takes expenses management module, which communicates with relational database by persistence layer, for example to prove its usability and practicability.