Research About Key Problems Of Component Based Software Development

Software development methods and technologies are the main research area of software engineer. With the advent of the information age with the core of computer software, software development technology has received more and more attention. In recent years, an important progress in the software field research is the software component. The methods of Component-Based Software Development (CBSD) integrate the existing components into specific application environment to build software systems for specific application, not only improve the production efficiency, reduce the development cost, but also significantly improve the reliability of the software. Therefore, the component technology has become a hot research field.Component library with a large number of reusable components is the prerequisites of support CBSD development. However, on the one hand, the traditional component description methods are lack of formal description of component function, causing the users hard to retrieve components satisfying user functional requirements from the massive components quickly and accurately; on the other hand, in order to ensure the quality of component system, component must be comprehensive, fully tested before storage. Due to the characteristics of the components inherent encapsulation, platform independence, and interface assembly and so on, existing software testing methods are not suitable for massive component testing environment. Therefore, it is necessary to develop automated testing methods and tools that suitable for the component characteristics to effectively testing components. In case of large number of assembled components, component users are difficult to predict the assembled component interface and behavioral characteristics. As a result, assembly components are often difficult to meet the design requirements. Above problems greatly restrict the practical application of CBSD.How to describe the dynamic behavior of a component to accurately retrieve the demand component, how to automate generate component testing cases for component fully testing, and how to assemble existing components to meet the application requirements of the system and specification the assembled system interfaces and behaviors become research hotspots and difficulties. Because of its precision and rigor, formal methods can better meet the component function description and interface specification requirements. Fusion of CBSD and formal development method for the development component software system has important theoretical value and practical significance. In this paper, Formal methods and genetic algorithm is applied to the component retrieval, component testing, component assembly and other components of software development key steps, designed to efficiently support component based software development.The research results and the main contents of this paper are summarized in the following three aspects:This paper first reference3C component model, proposed an extensible component description model based on formal method, including the component function description, interface description, environmental dependency description, and retained descriptions such as component keywords、non functional attributes and so on. Based on this description model and the psychology cognitive theory, a multiple fuzzy level and multistage component retrieve method is proposed. It is convenient for users to retrieve the component and ensure the retrieval accuracy and effectiveness.Secondly, in order to improve the efficiency of component automated testing, this paper proposed a components built-in testing case generation methods based on genetic algorithm, designed the chromosome encoding method of the testing points and testing data automate generation method based on component facets description. For improving testing case generation quality and speeding up the convergence rate of the genetic algorithm, this paper improved the calculate method of the fitness function of the algorithm. The fitness functions considered both of the coverage of the use case to the path and the increase rate of the path coverage. It effectively improves the coverage of the path and reduces the cost of use cases.The third part of this paper presents six kinds of component assembly mechanism:components sequence assembly mechanism, component selection assembly mechanism, component circulation assembly mechanism, component parallel assembly mechanism, component synchronous assembly mechanism and component interrupt assembly mechanism. By studying the way of derived composite component semantic specification according to the multiple components of the semantic specification and the related problems, proposed a CSP based component interface and behavior specification description method and the related derive algorithms. The effectiveness of the methods is verified by real cases.