A compositional approach to statecharts semantics

Abstract

Statecharts is a visual language for specifying reactive system behavior. The formalism extends traditional finite-state machines with notions of hierarchy and concurrency, and it is used in many popular software design notations. A large part of the appeal of Statecharts derives from its basis in state machines, with their intuitive operational interpretation. The classical semantics of Statecharts, however, suffers from a serious defect: it is not compositional, meaning that the behavior of system descriptions cannot be inferred from the behavior of their subsystems. Compositionality is a prerequisite for exploiting the modular structure of Statecharts for simulation, verification, and code generation, and it also provides the necessary foundation for reusability.