Jean-Pierre Talpin

An ML-Like Module System for the Synchronous Language SIGNAL

Synchronous languages, such as Signal, are best suited for the design of dependable real-time systems. Synchronous languages enable a very high-level specification and an extremely modular implementation of complex systems by structurally decomposing them into elementary synchronous processes. Separate compilation in reactive languages is however made a difficult issue by global safety requirements. To enable separate compilation of the functional components of reactive systems while preserving their global integrity, we introduce a module system for Signal. Just as data-types describe the invariants of program modules in functional languages, temporal and data-flow invariants interface Signal processes to their environment. In conventional languages, typing is the medium allowing the separate compilation of functions in a program. In Signal, the notion of conditional data-flow graph can similarly be used for separately compiling reactive processes and for assembling them in complex systems. Following this principle, we present the first design and implementation of a polymorphic type system and of a module system for the synchronous language Signal.

Modular Interpretation of Heterogeneous Modeling Diagrams into Synchronous Equations Using Static Single Assignment

The ANR project SPACIFY develops a domain-specific programming environment, Synoptic, to engineer embedded software for space applications. Synoptic is an Eclipse-based modeling environment which supports all aspects of aerospace software design. As such, it is a domain-specific environment consisting of heterogeneous modeling and programming principles defined in collaboration with the industrial partners and end users of the project : imperative synchronous programs, data-flow diagrams, mode automata, blocks, components, scheduling, mapping and timing. This article focuses on the essence and distinctive features of its behavioral or programming aspects : actions, flows and automata, for which we use the code generation infrastructure of the synchronous modeling environment SME. It introduces an efficient method for transforming a hierarchy of blocks consisting of actions (sequential Esterel-like programs), data-flow diagrams (to connect and time modules) and mode automata (to schedule or mode blocks) into a set of synchronous equations. This transformation significantly reduces the needed control states and block synchronizations. It consists of an inductive static-single assignment transformation algorithm across a hierarchy of blocks that produces synchronous equations. The impact of this new transformation technique is twofold. With regards to code generation objectives, it reduces the needed resynchronization of each block in the system with respects to its parents, potentially gaining substantial performance from way less synchronizations. With regards to verification requirements, it also reduces the number of states across a hierarchy of automata and hence maximizes model checking performances.

Modélisation compositionnelle d'architectures GALS dans un modèle de calcul polychrone

AADL est dedie a la conception de haut niveau et levaluation de systemes embarques. Il permet de decrire la structure dun systeme et ses aspects fonctionnels par une approche a base de composants. Des processus localement synchrones sont alloues sur une architecture distribuee et communiquent de maniere globalement asynchrone (systeme GALS). Une specificite du modele polychrone est quil permet de specifier un systeme dont les composants peuvent avoir leur propre horloge dactivation : il est bien adapte a une methodologie de conception GALS. Dans ce cadre, latelier Polychrony fournit des modeles et des methodes pour la modelisation, la transformation et la validation de systemes embarques. Cet article propose une methodologie pour la modelisation et la validation de systemes embarques specifies en AADL via le langage synchrone multi-horloge Signal. Cette methodologie comprend la modelisation de niveau systeme en AADL, des transformations automatiques du modele AADL vers le modele polychrone, la distribution de code, la verification formelle et la simulation du modele polychrone. Notre transformation prend en compte larchitecture du systeme, decrite dans un cadre IMA, et les aspects fonctionnels, les composants logiciels pouvant etre mis en œuvre en Signal. La generation de code distribue est obtenue avec Polychrony. Une etude de cas illustre notre methodologie pour la conception fiable des applications AADL.

Polychronous interpretation of synoptic, a domain specific modeling language for embedded flight-software

The SPaCIFY project, which aims at bringing advances in MDE to the satellite flight software indus- try, advocates a top-down approach built on a domain-specific modeling language named Synoptic. In line with previous approaches to real-time modeling such as Statecharts and Simulink, Synoptic features hierarchical decomposition of application and control modules in synchronous block dia- grams and state machines. Its semantics is described in the polychronous model of computation, which is that of the synchronous language SIGNAL.