Extending statecharts with duration

Abstract

Statecharts has been widely accepted as a successful graphical language for specifying reactive systems. However, some anomalies do exist when the durations of activities are subject to different interpretations such as with or without delay. A number of proposals have been put forward to address these anomalies but in a rather ad hoc fashion. The paper re-addresses these anomalies using a more uniform approach based on duration calculus. First, many anomalies are corrected by introducing new notations for specifying duration in statecharts. Second, the meanings of these notations are given in terms of duration calculus. Third, statecharts with duration can be subject to formal reasoning and hence verification. This framework delivers a more uniform extension to the graphical language as well as enables correctness with respect to duration to be studied formally using an established foundation.