Formal specification and implementation using a task flow diagram in interactive system design

In development of an application system, designing the user interface comes to occupy a larger part. Various techniques have been proposed and used for interactive system design. However, it is often pointed out that a design process of an inter-active system highly depends on designers' experience and lacks a systematic methodology. In this paper, a systematic method of interactive system design is proposed. First, the user task is specified as a task flow diagram. The diagram is refined by decomposing each task into several subtasks which represent system actions and user actions. A prototype can be generated automatically from a detailed task flow diagram augmented by information on user inter-face. The proposed method is explained by using on-line book purchasing problem.