Research And Application Of Data Access Layer Code Generation Method Based On Model Driven Architecture

The model and model transformation are the core concepts of Model Driven Architecture.The idea of MDA is to use the model as the product of each stage of software development and promote the whole development process of software through the transformation of the model.In addition,generating data access layer code from models is an important part of model-driven development.A method of code generation of data access layer based on MDA is proposed in this thesis.It is of great significance to improve the descriptive power of modeling language,reuse model and increase the efficiency of software development.First,the model,model transformation rules and four-layer metamodeling architecture in MDA are researched.The extension technologies in UML,MDD,domain model,and data access layer are studied.It turns out that the constraints of model elements which coexist in the same namespace is defined in UML metamodel,so that the metamodel of class diagram is unable to describe the semantic of symmetric unary association,resulting in missing semantic and generating incorrect code when the data access layer code is generated.Second,in order to understand the domain model,the semantics of class diagram in UML are represented using mathematical methods such as set,first-order logic,tree,and graph.The semantic of symmetric unary association which is ubiquitous in the real world is discussed in detail.In order to solve the modeling and code generation problems of symmetric unary association,the data structure of symmetric unary association is discussed according to its mathematical model.A method to make UML support symmetric unary association modeling by extending the meta-attribute and constraints in the metamodel of UML class diagram is proposed.The generation method of the entity class code of symmetric unary association is given.Third,based on the object-relational mapping problem of data access layer,the transformation rules and methods from object model to relational schema are given using QVT.In order to generate data access layer code from the object model,the structure of the data access layer code based on Hibernate is analyzed.The code generation rules and methods from object model to data access layer code are also given using QVT.Finally,the methods of extending the semantic of symmetric unary association and the methods of generating the data access layer code are applied to the development scenario of instant messaging software in the PowerDesigner.The modeling of the symmetric unary association and the generation of its data access layer code are implemented.The availability and validity of the methods are verified.