Communication concepts for statecharts: A semantic foundation

Abstract

Statecharts have proved their usefulness for the development of real-time systems; one imagines that a precise semantics of communication between components is required for any successful application to embedded systems. This contribution shows how to do this. First, sequential automata and a parallel composition operator are introduced. Then, we introduce a scoping construct for 'feedback' (signal sharing between explicitly-named components of a parallel composition). The syntactic closure of these operations is called the class of 'Mini-Statecharts'. We then discuss three different semantics that may be given to the feedback operator. They all have advantages and disadvantages, mainly mathematical, which are forthrightly discussed in depth and with clarity, using examples where necessary. The discussion is conducted within the framework of stream processing functions.