Section: New Results

A synchronous annex for the AADL

Participants : Loïc Besnard, Thierry Gautier, Paul Le Guernic, Jean-Pierre Talpin.

The SAE committee on the AADL adopted our recommendations to implement a timed and synchronous behavioural annex for the standard [20] . The specification and reference implementation of this revised behavioral annex will be the focus of most our attention next year.

We propose a synchronous timing annex for the SAE standard AADL. Our approach consists of building a synchronous model of computation and communication that best fits the semantics and expressive capability of the AADL and its behavioral annex and yet requires little to know (syntactic) extension to it, i.e. to identify a synchronous core of the AADL (which prerequisites a formal definition of synchrony at hand) and define a formal design methodology to use the AADL in a way that supports formal analysis, verification and synthesis.

Our approach first identifies the core AADL concepts from which time events can be described. Then, is considers the behavior annex (BA) as the mean to model synchronous signals and traces through automata. Finally, we consider elements of the constraint annex to reason about abstractions of these signals and traces by clocks and relations among them. To support the formal presentation of these elements, we define a model of automata that comprises a transition system to express explicit transitions and constraints, in the form of a boolean formula on time, to implicitly constraint its behavior. The implementation of such an automaton amounts to composing its explicit transition system with that of the controller synthesised from its specified constraints.