Rich Internet Application (RIA) has been proposed in order to solve the problems of current web applications. The user experience of current web applications is not comparable to desktop applications. RIA provides sophisticated interfaces for representing complex processes and data. Therefore, it requires collaboration between designers who design the interface and animation of an application and developers who implement business logics. In the development process of an application, the change of design is usually happened and it requires not only designer's work but also developer's work.Therefore, it costs a lot in large scaled applications. This paper provides a system which can provide complete separation of designer's and developer's work in source code level in order to reduce development costs for RIAs. In addition, we introduce this system into a practical system and evaluate its utility.