Communicating reactive processes

We present a new programming paradigm called Communicating Reactive Processes or CRP that unifies the capabilities of asynchronous and synchronous concurrent programming languages. Asynchronous languages such as CSP, OCCAM, or ADA are well-suited for distributed algorithms; their processes are loosely coupled and communication takes time. The ESTEREL synchronous language is dedicated to reactive systems; its processes are tightly coupled and deterministic, communication being realized by instantaneous broadcasting. Complex applications such as process of robot control require to couple both forms of concurrency, which is the object of CRP. A CRP program consists of independent locally reactive ESTEREL nodes that communicate with each other by CSP rendezvous. CRP faithfully extends both ESTEREL and CSP and adds new possibilities such as precise local watchdogs on rendezvous. We present the design of CRP, its semantics, a translation into classical process calculi for program verification, and application example, and implementation issues.