The Realization Of AOP Using Reflection And Meta-Object Protocol

Separation of concern is a basic principle of software engineering. Conventionalprogramming technologies are in difficulty of separating non-functional concernsfrom other ones. In order to overcome this difficulty, people put forward the thoughtof aspect-oriented programming (AOP). The thought of AOP is not conflicting withconventional programming technologies;actually it is an extension to them. The goalof AOP is to realize the localization of non-functional concerns and automaticcrosscutting of aspect code;one of its origins is the research of dynamic reflectiveobject-oriented languages and meta-object protocols (MOP).There are many mechanisms for the realization of AOP, such as adaptiveobject-oriented programming, composition filters and reflective meta-programming.This article applies itself to the study of realizing AOP using reflection and MOP. Thestructure of reflective meta-programming divides system into two levels: base leveland meta level, these levels are used to encapsulate functional concerns andnon-functional concerns individually. On the one hand, This level structure not onlyincarnates the principle of separation of concerns, but also realizes the localization ofnon-functional concerns;on the other hand, meta-object protocols defines interfacesused in the communication between base level and meta level and patterns used bymeta-objects to cooperate with each other in meta level. The process of meta-objects'transparent management on base-objects through MOP, is also the crosscuttingprocess of aspect code.Customizing a solution for AOP using reflection and MOP, and using this solutionin modeling process of the practical system, are problems this article tries hard tosolve, thus, how to solve these problems are innovations of this article. We putforward an AOP solution in this article, and put this solution into practice in thestructure design process of students' Courses Registration and Management System(CRMS). We also tell of the policies used to separate and compose different concernsin this article, and make an effective experiment in aspect-oriented programming.