Reasoning on Feature Models: Compilation-Based vs. Direct Approaches

Analyzing a Feature Model (FM) and reasoning on the corresponding configuration space is a central task in Software Product Line (SPL) engineering. Problems such as deciding the satisfiability of the FM and eliminating inconsistent parts of the FM have been well resolved by translating the FM into a conjunctive normal form (CNF) formula, and then feeding the CNF to a SAT solver. However, this approach has some limits for other important reasoning issues about the FM, such as counting or enumerating configurations. Two mainstream approaches have been investigated in this direction: (i) direct approaches, using tools based on the CNF representation of the FM at hand, or (ii) compilation-based approaches, where the CNF representation of the FM has first been translated into another representation for which the reasoning queries are easier to address. Our contribution is twofold. First, we evaluate how both approaches compare when dealing with common reasoning operations on FM, namely counting configurations, pointing out one or several configurations, sampling configurations, and finding optimal configurations regarding a utility function. Our experimental results show that the compilation-based is efficient enough to possibly compete with the direct approaches and that the cost of translation (i.e., the compilation time) can be balanced when addressing sufficiently many complex reasoning operations on large configuration spaces. Second, we provide a Java-based automated reasoner that supports these operations for both approaches, thus eliminating the burden of selecting the appropriate tool and approach depending on the operation one wants to perform

Pseudo-Booleanilainen optimisaatio käyttäen implisiittisiä osumisjoukkoja

There are many computationally difficult problems where the task is to find a solution with the lowest cost possible that fulfills a given set of constraints. Such problems are often NP-hard and are encountered in a variety of real-world problem domains, including planning and scheduling. NP-hard problems are often solved using a declarative approach by encoding the problem into a declarative constraint language and solving the encoding using a generic algorithm for that language. In this thesis we focus on pseudo-Boolean optimization (PBO), a special class of integer programs (IP) that only contain variables that admit the values 0 and 1. We propose a novel approach to PBO that is based on the implicit hitting set (IHS) paradigm, which uses two separate components. An IP solver is used to find an optimal solution under an incomplete set of constraints. A pseudo-Boolean satisfiability solver is used to either validate the feasibility of the solution or to extract more constraints to the integer program. The IHS-based PBO algorithm iteratively invokes the two algorithms until an optimal solution to a given PBO instance is found. In this thesis we lay out the IHS-based PBO solving approach in detail. We implement the algorithm as the PBO-IHS solver by making use of recent advances in reasoning techniques for pseudo-Boolean constraints. Through extensive empirical evaluation we show that our PBO-IHS solver outperforms other available specialized PBO solvers and has complementary performance compared to classical integer programming techniques

Du génie logiciel pour déployer, gérer et reconfigurer les logiciels

As a discipline, software engineering embraces various schools of thought, yet remains consistent with respect to its objective. It aims at providing means for effective and inexpensive production of software by contributing mathematical frameworks, methods and tools. Consequently, we witness some automation in software production process that, as of today, allows producing astronomical amounts of lines of code daily. This rapidly and massively produced software is required for all computer equipment that has invaded our daily life in various forms of other devices (PC, tablet, phone, refrigerator, car, etc.). In this world of large software consumption, it is somewhat surprising that the management of software, after its production, remains dominated by manual practices like searching in lists, downloading units and manual installations. In this context, I organized my research activities such that they aim at providing mathematical frameworks, methods and tools to deploy, distribute or update massive amounts of software since 2001, the year of my PhD defense. These research activities were mainly conducted in Brest at the CS department of Telecom Bretagne as part of the PASS team of IRISA. This document puts into perspective my various scientific contributions, undertaken projects, endeavors in training research students and efforts invested as a teacher. My scientific contributions can be divided into five parts: mathematical models and algorithms for dependency management in software deployment; software component models; processes and tools for massive software deployment; dynamic update of programs at runtime; languages for the design and implementation of software development processes. All these works complement each other, thus making it possible to imagine the proposition of methods and tools for large-scale software deployment.Le génie logiciel est une discipline constituée de nombreux courants mais cohérente par l'objectif affiché. Il s'agit d'aider à la production, de manière efficace et peu coûteuse, de logiciels en offrant des cadres mathématiques, des méthodes et des outils. Ainsi, on a pu assister à une certaine industrialisation du processus de production de logiciel qui permet aujourd'hui de produire, chaque jour, des quantités astronomiques de logiciel. Ce logiciel produit rapidement et en grande quantité est nécessaire pour tous les équipements informatiques qui ont envahi notre quotidien (ordinateur, tablette, téléphone, réfrigérateur, voiture, ...). Dans ce monde de grande consommation du logiciel, il est cependant surprenant de constater que la gestion des logiciels après leur production est resté dominé par des pratiques manuelles de recherche dans des listes, de téléchargement unitaire et d'installation manuelle. C'est dans ce cadre que j'ai développé une activité de recherche visant à fournir des cadres mathématiques, des méthodes et des outils pour déployer, diffuser ou mettre à jour massivement les logiciels depuis 2001 année de ma soutenance de thèse. Ces activités de recherche ont été conduites principalement à Brest au sein du département informatique de Télécom Bretagne dans le cadre de l'équipe PASS de l'IRISA. Mon Habilitation à Diriger des Recherches est l'occasion de remettre en perspective mes différentes contributions scientifiques, les étudiants formés à la recherche, les projets réalisés ainsi que mon investissement en tant qu'enseignant. Les contributions scientifiques peuvent être classées en cinq parties : - des modèles mathématiques et les algorithmes associés pour la gestion des dépendances de logiciels lors de leur déploiement ; - les modèles de composants logiciels ; - les processus et outils pour le déploiement de logiciel massif ; - la mise à jour de programmes sans interrompre leur exécution ; - des langages pour la conception et la réalisation de processus de développement logiciel. Tous ces travaux qui se nourrissent et se complètent permettent d'imaginer la proposition de méthodes et outils pour passer à l'échelle dans la gestion du déploiement des logiciels