Embedding Domain-Specific Modelling Languages in Maude Specifications

Extended version accepted in the Systems and Software Engineering Journal.International audienceWe propose an approach for embedding Domain-Specific Modelling Languages (\dsml) into Maude, based on representing models and metamodels as Maude specifications, and on representing operational semantics and model transformations as computable functions/relations between such specifications. This provides us, on the one hand, with abstract definitions of essential concepts of domain-specific modelling languages: model-to-metamodel conformance, operational semantics, and (operational-semantics-preserving) model transformations; and, on the other hand, with equivalent executable definitions for those concepts, which can be directly used in Maude for formal verification purpose

Embedding domain-specific modeling languages into Maude specifications

International audienceWe propose a formal approach for the definition and analysis of domain-specific modelling languages (DSML). The approach uses standard model-driven engineering artifacts for defining a language's syntax (using metamodels) and its operational semantics (using model transformations). We give formal meanings to these artifacts by translating them to the Maude language: metamodels and models are mapped to equational specifications, and model transformations are mapped to rewrite rules between such specifications, which are also expressible in Maude thanks to Maude's reflective capabilities. These mappings provide us, on the one hand, with abstract definitions of the MDE concepts used for defining DSML, which naturally capture their intended meanings; and, on the other hand, with equivalent executable definitions, which can be directly used by Maude for formal verification. We also study a notion of operational semantics-preserving model transformations, which are model transformations between two DSML that ensure that each execution of a transformed instance is matched by an execution of the original instance. We propose a semidecision procedure, implemented in Maude, for checking the semantics-preservation property. We also show how the procedure can be adapted for tracing finite executions of the transformed instance back to matching executions of the original one. The approach is illustrated on xSPEM, a language for describing the execution of activities constrained by time, precedence, and resource availability

Prototyping the Semantics of a DSL using ASF+SDF: Link to Formal Verification of DSL Models

A formal definition of the semantics of a domain-specific language (DSL) is a key prerequisite for the verification of the correctness of models specified using such a DSL and of transformations applied to these models. For this reason, we implemented a prototype of the semantics of a DSL for the specification of systems consisting of concurrent, communicating objects. Using this prototype, models specified in the DSL can be transformed to labeled transition systems (LTS). This approach of transforming models to LTSs allows us to apply existing tools for visualization and verification to models with little or no further effort. The prototype is implemented using the ASF+SDF Meta-Environment, an IDE for the algebraic specification language ASF+SDF, which offers efficient execution of the transformation as well as the ability to read models and produce LTSs without any additional pre or post processing.Comment: In Proceedings AMMSE 2011, arXiv:1106.596

Methods and tools for the integration of formal verification in domain-specific languages

Les langages dédiés de modélisation (DSMLs) sont de plus en plus utilisés dans les phases amont du développement des systèmes complexes, en particulier pour les systèmes critiques embarqués. L’objectif est de pouvoir raisonner très tôt dans le développement sur ces modèles et, notamment, de conduire des activités de vérification et validation (V and V). Une technique très utilisée est la vérification des modèles comportementaux par exploration exhaustive (model-checking) en utilisant une sémantique de traduction pour construire un modèle formel à partir des modèles métiers pour réutiliser les outils performants disponibles pour les modèles formels. Définir cette sémantique de traduction, exprimer les propriétés formelles à vérifier et analyser les résultats nécessite une expertise dans les méthodes formelles qui freine leur adoption et peut rebuter les concepteurs. Il est donc nécessaire de construire pour chaque DSML, une chaîne d’outils qui masque les aspects formels aux utilisateurs. L’objectif de cette thèse est de faciliter le développement de telles chaînes de vérification. Notre contribution inclut 1) l’expression des propriétés comportementales au niveau métier en s’appuyant sur TOCL (Temporal Object Constraint Language), une extension temporelle du langage OCL; 2) la transformation automatique de ces propriétés en propriétés formelles en réutilisant les éléments clés de la sémantique de traduction; 3) la remontée des résultats de vérification grâce à une transformation d’ordre supérieur et un langage de description de correspondance entre le domaine métier et le domaine formel et 4) le processus associé de mise en oeuvre. Notre approche a été validée par l’expérimentation sur un sous-ensemble du langage de modélisation de processus de développement SPEM, et sur le langage de commande d’automates programmables Ladder Diagram, ainsi que par l’intégration d’un langage formel intermédiaire (FIACRE) dans la chaîne outillée de vérification. Ce dernier point permet de réduire l’écart sémantique entre les DSMLs et les domaines formels. ABSTRACT : Domain specific Modeling Languages (DSMLs) are increasingly used at the early phases in the development of complex systems, in particular, for safety critical systems. The goal is to be able to reason early in the development on these models and, in particular, to fulfill verification and validation activities (V and V). A widely used technique is the exhaustive behavioral model verification using model-checking by providing a translational semantics to build a formal model from DSML conforming models in order to reuse powerful tools available for this formal domain. Defining a translational semantics, expressing formal properties to be assessed and analysing such verification results require such an expertise in formal methods that it restricts their adoption and may discourage the designers. It is thus necessary to build for each DSML, a toolchain which hides formal aspects for DSML end-users. The goal of this thesis consists in easing the development of such verification toolchains. Our contribution includes 1) expressing behavioral properties in the DSML level by relying on TOCL (Temporal Object Constraint Language), a temporal extension of OCL; 2) An automated transformation of these properties on formal properties while reusing the key elements of the translational semantics; 3) the feedback of verification results thanks to a higher-order transformation and a language which defines mappings between DSML and formal levels; 4) the associated process implementation. Our approach was validated by the experimentation on a subset of the development process modeling language SPEM, and on Ladder Diagram language used to specify programmable logic controllers (PLCs), and by the integration of a formal intermediate language (FIACRE) in the verification toolchain. This last point allows to reduce the semantic gap between DSMLs and formal domains

Towards the Formal Verification of Model Transformations: An Application to Kermeta

Model-Driven Engineering (MDE) is becoming a popular engineering methodology for developing large-scale software applications, using models and transformations as primary principles. MDE is now being successfully applied to domain-specific languages (DSLs), which target a narrow subject domain like process management, telecommunication, product lines, smartphone applications among others, providing experts high-level and intuitive notations very close to their problem domain. More recently, MDE has been applied to safety-critical applications, where failure may have dramatic consequences, either in terms of economic, ecologic or human losses. These recent application domains call for more robust and more practical approaches for ensuring the correctness of models and model transformations. Testing is the most common technique used in MDE for ensuring the correctness of model transformations, a recurrent, yet unsolved problem in MDE. But testing suffers from the so-called coverage problem, which is unacceptable when safety is at stake. Rather, exhaustive coverage is required in this application domain, which means that transformation designers need to use formal analysis methods and tools to meet this requirement. Unfortunately, two factors seem to limit the use of such methods in an engineer’s daily life. First, a methodological factor, because MDE engineers rarely possess the effective knowledge for deploying formal analysis techniques in their daily life developments. Second, a practical factor, because DSLs do not necessarily have a formal explicit semantics, which is a necessary enabler for exhaustive analysis. In this thesis, we contribute to the problem of formal analysis of model transformations regarding each perspective. On the conceptual side, we propose a methodological framework for engineering verified model transformations based on current best practices. For that purpose, we identify three important dimensions: (i) the transformation being built; (ii) the properties of interest ensuring the transformation’s correctness; and finally, (iii) the verification technique that allows proving these properties with minimal effort. Finding which techniques are better suited for which kind of properties is the concern of the Computer-Aided Verification community. Consequently in this thesis, we focus on studying the relationship between transformations and properties. Our methodological framework introduces two novel notions. A transformation intent gathers all transformations sharing the same purpose, abstracting from the way the transformation is expressed. A property class captures under the same denomination all properties sharing the same form, abstracting away from their underlying property languages. The framework consists of mapping each intent with its characteristic set of property classes, meaning that for proving the correctness of a particular transformation obeying this intent, one has to prove properties of these specific classes. We illustrate the use and utility of our framework through the detailed description of five common intents in MDE, and their application to a case study drawn from the automative software domain, consisting of a chain of more than thirty transformations. On a more practical side, we study the problem of verifying DSLs whose behaviour is expressed with Kermeta. Kermeta is an object-oriented transformation framework aligned with Object Management Group standard specification MOF (Meta-Object Facility). It can be used for defining metamodels and models, as well as their behaviour. Kermeta lacks a formal semantics: we first specify such a semantics, and then choose an appropriate verification domain for handling the analysis one is interested in. Since the semantics is defined at the level of Kermeta’s transformation language itself, our work presents two interesting features: first, any DSL whose behaviour is defined using Kermeta (more precisely, any transformation defined with Kermeta) enjoys a de facto formal underground for free; second, it is easier to define appropriate abstractions for targeting specific analysis for this full-fledged semantics than defining specific semantics for each possible kind of analysis. To illustrate this point, we have selected Maude, a powerful rewriting system based on algebraic specifications equipped with model-checking and theorem-proving capabilities. Maude was chosen because its underlying formalism is close to the mathematical tools we use for specifying the formal semantics, reducing the implementation gap and consequently limiting the possible implementation mistakes. We validate our approach by illustrating behavioural properties of small, yet representative DSLs from the literature