基于特征的构件模型及其规范化设计过程

Feature-Based Component Model and Normalized Design Process

基于构件的软件复用是解决软件危机的重要手段,但目前还缺乏规范化的模式和方法以支持具有高复用性能的构件的识别与设计,借助特征空间作为工具以解决上述问题.首先介绍特征与特征空间的概念,从特征变化的相互依存关系入手,提出特征依赖的概念和4种具体的特征依赖.在此基础上,给出了基于特征空间的构件模型,使用特征的“型-值”机制与特征依赖表达构件的复用性.然后讨论了构件复用度的度量手段和规范化设计的目标,提出4种构件规范化模式(原子模式、基本模式、框架模式和内聚模式),研究了以特征空间分解为基础的规范化方法,并通过实例加以验证.该方法实现了多粒度、多模式构件的共存和构件间基于组合的松散耦合,从而提高了构件的复用效率并降低复用成本.结果在企业资源计划(enterprice resource planning,简称ERP)系统的构件化设计与开发中得到广泛应用,对指导构件设计具有较高的理论与实践价值.

Component-Based development method is thought to be an effective technique to tackle software crisis, but in practice it didn＇t reach the expectation, and currently there lack of normal forms and normalized methods to support identification and design of components with high reusability. This paper tries to solve this problem with feature space as a tool. Theory of feature and feature space is firstly introduced, and by analysis of dependencies between features＇ variability, the concept of feature dependency （FD） and four types of FDs are elaborated. Then a component specification model based on feature space is presented, in which component reusability is expressed by feature＇s ＇type-value＇ variation mechanism and feature dependencies. After that, goals of component design and several reusability metrics are briefly discussed, and four component normal forms and the corresponding normalization algorithms based on feature space decomposition are presented in detail. A practical case is finally shown to validate the methods. The normal forms and normalized design methods realize the multi-grained and multi-form components＇ co-existence and the loosely composition-based coupling between components, which result in higher reusability, higher reuse efficiency, and lower reuse cost. The methods have been widely applied in the design and implementation of component -based Enterprise Resource Planning （ERP） systems, and have shown great theoretical and practical significance to component design.