A scenario-based approach to hierarchical state machine design

One of the most crucial and complicated phases of real-time system development lies in the transition from system behavior (generally specified using scenario models) to the behavior of interacting components (typically captured by means of communicating hierarchical finite state machines). It is commonly accepted that a systematic approach is required for this transition. We overview such an approach, which we root in a hierarchy of "behavior integration patterns" we have elaborated. The proposed patterns guide the structuring of a component's behavior and help in integrating the behavior associated with new scenarios into the existing hierarchical finite state machine of a component. One of these patterns is discussed at length.