Hierarchical Communicating Real-Time State Machines

This paper proposes a methodology for the development of distributed real-time (RT) systems using the Communicating Real-Time State Machines (CRSMs) formal specification language. The methodology is novel in that it addresses complex systems by extending CRSMs with concepts borrowed from Statecharts, and favours timing predictability through a holistic integration of an RT system and its operating software, i.e., message-based runtime executive. A full life cycle is established where all the development phases are unified by a common runtime representation based on actors used both for prototyping and temporal analysis and for final implementation. The paper describes the methodology and shows its practical use through examples. Java is the implementation language.