Statemaster: a user interface management system based on statecharts

Designing and implementing a user interface (UI) is among the costliest tasks in developing interactive software systems. As a result, much work is being done in the area of User Interface Management Systems (UIMSs). These systems make it easier to develop complex user interfaces more quickly because specification of user interface dialogs is at a closer level to that at which UI designers express themselves. This paper describes the generic structure ofa UIMS and several examples ofprevious work in the field. Many UIMSs are implemented as explicit state machines that use conventional state transition diagrams or statemetaphors to specify dialogs. The rest of this paper describes the design and implementation of Statemaster, an event-driven UIMS based on statecharts. Statecharts are a hierarchical extension of state diagrams well suited for describing complex reactive systems with a compact, visual notation. These diagrams are directly implemented by Statemaster with an object-oriented architecture in the C++ programming language. Statemaster has been found to be general enough to implement a wide range of user interface dialogs. It can be used as a prototyping tool for UI development, and it is efficient enough to be used as the final, target-intent implementation.