Research On Component Formal Semantic And Combination

With the rapid increase of software requirement, the ambassador scale of software system, and the function of software is becoming more complex. Traditional software development methods are difficult to meet the needs of users today. Component-based software development methodology becomes a hot topic of software engineering. Systems are built by component reuse or combination, which significantly shorten the software development cycle and improve the efficiency of generating software to ensure the quality of software products. In CBSD, individual functions component can not meet the users’ business requirements effectively, which need to obtain more powerful function system components. This paper will firstly research the formal semantics of components, and then study the combination technologies between components.Firstly, this paper presented a category model for component using category theory. Components were defined for the set of component protocols and component realization. The component protocols were defined by formally described the interfaces, attributes, function and structure of components. The relationships between component protocols were described to be morphisms by mapping relationship between interfaces and relationships between properties of components. Based on these, we used components and their morphism relationships to build category models of components.Then, according to the component interactions relationships, the paper provides two types of component combination method using category theory. For two independent components, we used sum operator of category theory to combine into a new composite component; for the combination with the interaction of two components, we used pushout operator to construct a new composite component. The logical relationship among present layer, business logic layer and data access layer were characterized by functor in category theory, which helps developers to build systems’architecture more effectively.Finally, we provide a example, named the surveying and designing project management information system, to introduce the component formal description and combination process based on category theory. The system using three-tier architecture as software development framework, gives five basic function component model of different abstraction layers and use category functor to map the relationship between different abstraction layers, ultimately achieve the realization of the entire software system.