| The software industry plays a key role in IT industry, and this situation continues to be strengthened and highlighted since in the 21st century. With the development of technologies of software industry, the requirements of both the software and the hardware are becoming stricter and stricter. In order to continuously improve the efficiency of software development, the researchers have been working hard to explore the approach all the while. Many emerging software technologies, such as object-oriented programming, component-based development, pattern, distributed computing, etc, all make a certain contributions for the improvement of software quality and the extension of the life cycle of software. However, the developer will be at a loss in the face of the system's interoperability across different middleware vendors, the portability of software and the asynchronous problem between the documents and codes in the development process. In the year of 2001, the Object Management Organization (OMG) introduced a new software development framework - Model Driven Architecture (MDA), which not only solves the problems of traditional software development, but also complements with other new approaches, and thus opens a new chapter for the software development.MDA deals with the complexity of software development by raising the level of abstraction, in which the business logic designs are separated from the concrete platform. Platform Independent Models (PIM) which are unrelated to specific implementation techniques should be built firstly, and then, Platform Specific Models (PSM) can be achieved through model transformation, in which more implementation details are introduced. Finally, according to the PSM, the executable target code will be generated automatically by code generator. The research of the Middleware Company have proved that a lot of benefits can be obtained from MDA, such as rapid development, enhancement of system's portability, improvement of code consistency and maintainability, and architecture advantages.Most of Web applications on J2EE platform are based on a certain kind of framework, such as Struts, Spring, JSF, Cocoon, Axis and Xalan, etc, which are all widely used. These frameworks are design patterns summarized by the developers from their past experience and lessons. The application of these patterns can not only reduce the cost of software development, but also guarantee the quality of Web applications. Currently, platform specific models in most MDA-based development approach for Web applications are defined as the concrete framework on which the target system running, and the code generator are closely bound with these frameworks, such as OptimalJ, Rational XDE, Arcstyler, AndroMDA, and so on, which lead to a close coupling between platform specific design models and the target frameworks, and thus weaken the portability of system models and reduce the reusability of software designs.In order to resolve the problems given above, the description of the target framework for web application is added in the extended MDA-based development model which supporting multi-target-frameworks, and in which abstract platform specific model and concrete platform specific model is introduced. This approach enhances the clarity and agility of model descriptions, and the reusability of models can be fully embodied. Both the PIMs and the PSMs can be used on different frameworks. Thereby, many kinds of target codes for different frameworks can be generated according to the requirements with just a design.The research of this paper is an extension and prolongation of MDA, which can provide a positive effect on automatic code generation and make an effective support to model-driven software development. |
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