Research Of Component Composition Based On Scenarios

As the increase of the software system complexity, the abstraction of software requirements is becoming more and more difficult. In a complex software system, we need to fully describe the scenarios, and formally model the system structure. In software engineering, the components can be encapsulated object class, class trees, software frameworks, software architecture, some functional modules, documents, analysis pieces and design patterns, and so on. The characteristics of the components enable itself as the core technology to achieve software reusability, such as independency, encapsulation, reusability and commonality. When the existed components can not satisfy the application requirements, the software could build new components to satisfy the application according to certain specific requirements. In order to achieve the goal of high cohesion and low coupling, a formal modeling approach of component model is researched and presented. And new applications system could be developed through a composition of component model, so as to achieve complex systems development through the reusability of component. Component composition is actually achieved by the interaction and collaboration between each other. The process can achieve system-specific functional and non-functional requirements and re-build the system components to achieve business value-added features of a process.Based on the former research of component reuse and category technology, this paper proposes a component composition method based on event track by the combination of category theory and component technology and reference of formal modeling method. Currently, it adopts graphic with texture or formal description language for modeling components. However these methods are not good at describing the dynamic behavior of components, interoperability and so on. The category theory focuses on the relationship between objects, which can determine the nature of the interconnections that can be established between system components. Therefore, the research utilities the category theories and principles to abstract the application needs, and applies the category theory to abstract the component and the process of component composition. The component could be divided into two parts:component implement and component interface. Component implement is described by the process behaviors based on event track and track and process morphisms are shown to form a complete category where parallel composition is reflected by pullback, process morphisms reflect different forms of inheritance; and component interface is described by the observation based on process behaviors, component and component morphisms are shown to form a cocomplete category where component behavior composition with synchronization constraints is reflected by colimit, component morphisms reflect inclusion. This also proves the feasibility to utilize the category theory and technology to solve the problem of component interaction behavior.The paper preliminarily discusses the components and the implementation of component compositions thought category theory taking the Teacher-Student Course Selection System as an example. The research explicitly demonstrates that it advantage in solving parallel composition of component behaviors with synchronization constraints, and the effectiveness and the feasibility in solving the problem of component composition. Furthermore, category theory is introduced into software engineering as an efficient mathematics tool.