Synchronous Programming of Reactive Systems

This book presents a synthesis of recent works concerning reactive system design. The term 'reactive system' has been introduced in order to avoid ambiguities often involved with the term 'real-time system' which, while being best-known and suggestive, has been assigned so many different meanings that it is almost inevitably misunderstood. Industrial Process control system, transportation control and supervision systems, signal processing systems, etc. are examples of the systems we have in mind. Four programming languages are presented, which share the same underlying synchronous model: based on Robin Milner's pioneering works about synchronous process algebras, this model consists in considering that a program instantaneously reacts to events, or that the machine execution time is negligible with respect to the response delays of its environment. Using this abstract point of view, the time behavior of a system can be formalized in a very simple and elegant way. The languages presented are ESTEREL, a textual imperative language; ARGOS, a graphical language inspired by STATECHARTS; and LUSTRE and SIGNAL, two declarative languages. After a tutorial description of the languages, illustrated by various examples, a set of related tools is presented: compilers to sequential and distributed code, silicon compilers, verification tools.