| With the constantly improvement of the enterprise information, the demands of software are also more and more high. The main performances are in two aspects: On one hand, the development efficiency of software must be raised and all kinds of enterprise resources must be reused too. Software reuse offers a solution to eliminate repeated work and improve efficiency and quality in the software development .In the recent ten years, object-oriented technology has appeared and become a mainstream technology, thereby providing fundamental technology support for software reuse. Software reuse regains more attention in software engineering research and is considered a practical and feasible approach to solve the software crisis. At the same time, software component technology plays an important role in distributed object research.Software component technology is a method, which uses component composition technology to develop application system. It completely changes the traditional "from scratch" software development methods though the pre-established component interface. The whole application system meets different needs by component replacement or upgrade and adds new functions by adding new components or component composition.On the other hand, in a long run process, software system will encounter a variety of changes, such as changes in requirements, realization and business processes etc. In the past, most changes are based on the demands. It develops new functional or updates the old function modules, compiles to form a new application system, finally deploy the module into the software system. This is the upgrading process of the static evolution of software. But, for some of the systems which need continuous working such as air traffic control systems, global financial trading systems, industrial control systems, network services and so on, stopping the operation of the entire system software to update will result in unacceptable loss. It requires software system not to stop running to update in those cases. This method is called the dynamic evolution of the software.In this paper, on the basis of the software component technology, combining with PLM system development practices, the component technology ideology has been achieved in the project. It includes: the methods of software reuse and component-oriented development, the field component library design and implementation, the component composition environmental design and implementation, the theory of software flexibility and adaptability, the methods of software maintenance and evolution, and so on. In these fields, the results which are obtained are as follows:(1) The component-oriented software development methods are used in the practice of PLM system development, and a development method is summarized. It includes architecture design, component selection, component composition and system maintenance and evolution. In PLM, the construction design uses the unification modeling language (UML) to analysis the basic business flow, and it divides service functional module preliminarily. Then, the process is repeated and finally it makes the division more and more refinement. At last, a few of small and reusable components are divided successfully;(2) The business-oriented field component library is designed and developed. It not only includes code-level component, but also includes a variety of file-level components to enhance the scope of the reuse. Towards the reusable components which are divided by UML, first of all, it searches the existing enterprise component library, uses facet classification to improve the component searching precision. For the component which does not exist in the component library, it uses the way of manual development, adopts the visual composition environment which is based on the WEB. The developers do not need develop from zero again. The composition environment provides massive reusable resources, which improve the developing efficiency. By the code view interface, the codes can be edited to complete the new component's development. At last, the new component will be loaded into the component library and be prepared to reuse in the future.(3) The development of the page-level component is completed. And the PLM component composition environment is implemented. It is divided into WEB component management, form modeling tools, business component management, and realized the process of composition. WEB component management environment manages massive reusable developing resources. So, many hard works which did repeatedly can be avoided. Form modeling tool is the center of the development of WEB pages component which adopts visual development way to complete the composition. Regarding the problem of conflicted interface, this modeling tool provides the code view pattern, which can revise the completed component code. Business component management manages the completed business component. It saves the paths information of the original documents and the code which has produced by code view. Thus, it will be found and reused conveniently. The document also can be opened by form modeling tool to add, delete or revise the code and function.(4) The MIS issue of adaptability and flexibility are proposed. The system development is divided into first and second processes. The expansion and adaptability in the system are embodied in the second development. The system flexibility requests the system has the outside change ability. This change comes from three aspects: firstly, the user's needs changes continuously with time. Secondly, the enterprise business workflow and the method of management change. The third reason refers to the update of computer technology, network technology, automatic and management technology, which change the software development pattern.(5) This paper studies the problem of EJB component migration and component migration restraint. Then on the basis of it, a distributed EJB component evolution system based on JAVA reflective mechanism is discussed. Finally, the application system's demonstrated process is given. EJB component migration includes the question of the reference migration, the state migration and the lost of client's request etc. So, it has to restrain the process of component migration. Then, the feature of JAVA reflective mechanism and the JAVA class-loader are analyzed. The JAVA reflective mechanism provides reflective API to call for the outside methods. Moreover, it realizes the ability of gaining the object by its name string. The JAVA class loader is the core class of JAVA language. Fortunately, JAVA provides self-definition class-loader and it can define any position in the network as the source of loaded class. At last, the approach of distributed evolution system is designed. In addition, the process of evolution is demonstrated and the system's defects are proposed. |
PDF Full Text Request