Programming Distributed Reactive Systems: a Strong and Weak Synchronous Coupling

. Reactive and real-time systems often require temporal and logical safety, concurrency and determinism. Several asynchronous and strong synchronous answers have been proposed to this problem. However, asynchronous languages such as CSP or CCS force the user to choose between determinism and concurrency, for they base concurrency on asynchronous implementation models where processes nondeterministically compete for computing resources. On the other hand, strong synchronous implementations are purely sequential. The aim of this paper is to present a new paradigm for reactive distributed programming, weak synchronism, responding to concurrency and determinism. We define a small language of communicating reactive kernels, and characterize it by an operational semantics. This semantics is then discussed w.r.t. three criteria, responsiveness, modularity and causality, formulated by C. Huizing in [10]. We show that the weak synchronous paradigm provides a deterministic semantics of concurr..

Programming Communicating Distributed Reactive Automata: the Weak Synchronous Paradigm

The aim of this paper is to present a new paradigm for reactive and real-time distributed programming: weak synchronism. We define a small language for communicating reactive automata, and characterize it by an operational semantics. We show that weak synchronism provides a deterministic semantics of concurrency and allows physical distributed implementations. This weak synchronous paradigm can then be extended to real-time programming, by defining a more general paradigm, a strong-weak synchronous coupling. Keyword codes: D.1.3; F.3.2; F.4.3 Keywords: Concurrent Programming; Semantics of Programming Languages; Formal Languages. 1. Introduction: Real-Time and Reactive Systems The concept of reactive system was introduced by D. Harel and A. Pnueli in [8] to describe systems which maintain a continuous interaction with their environment. D. Harel and A. Pnueli propose a dichotomy between what they call transformational and reactive systems. On the one hand, a transformational system a..

Synchronous Communicating Reactive Processes

Reactive and real-time systems often require temporal and logical safety, concurrency and determinism. Several asynchronous or strong synchronous answers have been proposed to this problem. However, asynchronous calculi such as CCS generally force the user to choose between determinism and concurrency. On the other hand, strong synchronous implementations are sometimes difficult to distribute. The aim of this paper is to present a paradigm for concurrent reactive programming, weak synchronism, responding to both concurrency and determinism. A calculus of deterministic synchronous communicating reactive processes is defined, and a high level model for programming distributed reactive systems is proposed. Keywords : process algebra, reactive and real-time systems, concurrency, synchronous languages. 1 Introduction Real time systems are often consider as composed of two layers: (a) a set of transformational tasks that perform classical computations, and (b) a reactive sub-system that ma..

A Component Based Methodology for Description of Complex Systems. An Application to Avionics Systems

In this paper, we present a component based methodology for the description of complex systems and its application to the field of avionics components design. Avionics design involves several engineering branches, namely physics, electronics and computational science. Three viewpoints are extracted from this context: architectural, operating and functional viewpoints. The case study we use to illustrate this paper describes the compositional design of a subsystem of an aircraft's flight controls. We show the description and composition of multiple viewpoints, the expression of critical properties on independent viewpoints, as well as on the resulting composite system. In a second step, we discuss how existing formal specification and verification techniques can be used to achieve requirement meeting verification. An application on the case study is also provided

Partially Bounded Context-Aware Verification

International audienceModel-checking enables the formal verification of software systems. Powerful and automated, this technique suffers, however, from the state-space explosion problem because of the exponential growth in the number of states with respect to the number of interacting components. To address this problem, the Context-aware Verification (CaV) approach decomposes the verification problem using environment-based guides. This approach improves the scalability but it requires an acyclic specification of the verification guides, which are difficult to specify without losing completeness. In this paper, we present a new verification strategy that generalises CaV while ensuring the decomposability of the state-space. The approach relies on a language for the specification of the arbitrary guides, which relaxes the acyclicity requirement, and on a partially-bounded verification procedure. The effectiveness of our approach is showcased through a case-study from the aerospace domain, which shows that the scalability is maintained while easing the conception of the verification guides