Why Are Modalities Good for Interface Theories?

Abstract

Pourquoi les modalités sont importantes pour la conception par interfaces? Résumé : Dans ce papier, les caractéristiques fondamentales d'une théorie pour la conception de composant par le biais d'interfaces sont revisitées. Des considérations méthodologiques rendent essentiel le support de la conception par "aspects" et par "hypothèse/garantie". Ainsi, en plus des habituelles propriétés de raffinement et substituabilité des interfaces, deux opérations supplémentaires sont nécessaires : la conjonction et la résiduation (ou quotient). Une difficulté naît lorsque les interfaces portent sur des alphabets différents-celle-ci est etudiéeà travers uneétape d'égalisation d'alphabet. Nous montrons que cetté egalisation doitêtre effectuée différemment en fonction du type d'opération. Nous montrons que les spécifications modales, adaptation d'un formalisme originalement proposé par Kim Larsen, offrent alors la flexibilité nécessaire.

An algebraic theory of interface automata

“…A modal specification characterises sequences of (non I/O) interactions between a component and its environment, along with modalities on the interactions, indicating whether an interaction may or must be possible. Raclet et al [33,35,34] introduce a specification theory for modal specifications that considers a substitutive refinement relation, along with the operations of parallel composition, conjunction and quotient [32]. Their notion of liveness and progress is based on must-modalities, and thus differs from our trace-based formulation.…”

“…Consequently, the conjunction of components is the coarsest component that is a refinement of its operands (i.e. is the meet operator), which is why it is frequently referred to as the shared refinement operator [15,35].…”

“…Their notion of liveness and progress is based on must-modalities, and thus differs from our trace-based formulation. The theory is extended in [35,34] to modal interfaces (modal specifications with I/O distinction), where a mapping is given from deterministic interface automata without hidden actions to modal interfaces. This is similar to the theory of Larsen et al [24], except that: a number of technical issues are resolved, relating to compatibility and parallel composition; refinement is based on trace-containment, rather than being game-based; and additional compositional operators are defined.…”

“…A weakness of [35,34] is that the compositionality results for the different operators must be given with respect to either strong or weak refinement relations (the former for parallel and quotient, the latter for conjunction) when the components to be composed have dissimilar alphabets. This has repercussions for parallel composition, which is an asynchronous operator on interface automata, but is treated synchronously on modal interfaces by a lifting on alphabets.…”

Checking Thorough Refinement on Modal Transition Systems Is EXPTIME-Complete

“…The MTS framework was suggested more than 20 years ago by Larsen and Thomsen [15] and has recently brought a considerable attention due to several applications to e.g. componentbased software development [17,6], interface theories [21,18], modal abstractions and program analysis [10,13,16] and other areas [9,22], just to mention a few of them. A renewed interest in tool support for modal transition systems is recently also emerging [7,8].…”