Towards Dynamic Software Product Lines: Unifying Design and Runtime Adaptations

In the recent years, we have witnessed major advances in mobile computing. Modern devices are equipped with a variety of sensors and network interfaces that make them quite versatile. In order to take advantage of all the hardware capabilities and provide a better user experience, software has to be context aware, i.e. it has to monitor the events and information coming from its environment and react accordingly. At the same time, we notice that an important number of such mobile applications share several characteristics regarding its architecture, communication, storage and interfaces. This leads us to consider that context-aware systems can also benefit from the Software Product Line (SPL) paradigm. SPLs were defined to take advantage of commonalities through the definition of reusable artifacts, in order to automate the derivation of multiple products. Nevertheless, SPLs are limited regarding the runtime modifications implied by context awareness. This dissertation investigates on Dynamic Software Product Lines (DSPL). A DSPL extends a classic SPLs by providing mechanisms to adapt products at runtime to cope with dynamic changes imposed by context awareness. Our main goal is to unify design and runtime adaptations under the same definition through high-level artifacts. Such artifacts can then be used to implement DSPLs by defining the processes required to map them into concrete products at design time and at runtime. Concretely, as the first contribution of this dissertation, we introduce both: a simple - yet complete - variability model, and a composition model that realizes variability. With the variability model we aim at defining a family of products and at identifying commonalities and variabilities along those products using variants. The composition model on the other side, is based on ideas from Aspect Oriented Software Development (AOSD). We use the model to divide the products in several modules called aspect models that are used to construct platform independent representations of variability. Each aspect model is formed by three parts: the architecture model which represents parts of a system to be added, the advice that contains a set of changes to the core application and finally, the pointcut that identifies the places where the modifications are performed. As a second contribution, we propose two processes of product derivation: design weaving and runtime weaving. Design weaving aims at building a single product. Runtime weaving aims at adapting a product being executed. Both processes use the same variability and aspect models. We thus allow developers to reuse the same artifacts used for building a software product to adapt it dynamically among various configurations. For the design weaving, we base ourselves on a model driven approach where transformations and code generation are employed to obtain source code from a set of models. For the runtime weaving, we use FraSCAti, a service and component based platform with dynamic properties, to execute reconfigurations during the execution of products. We also use a context manager to process events coming from the environment and make decisions about the adaptation. To validate our approach we define and implement a DSPL. Concretely, this research is part of the FUI CAPPUCINO project, which aims at building mobile applications for ubiquitous environments. We have implemented a DSPL for a retail case study. We successfully cover the whole cycle of design derivation and adaptation of software products. The scenario demonstrates the versatility of our approach and in particular the unification achieved through the aspect models used at design time as well as at runtime.Pour profiter des nombreux matériels actuellement, les logiciels s'exécutant sur des téléphones mobiles doivent devenir sensibles au contexte, c'est-à-dire, qu'ils doivent surveiller les événements provenant de leur environnement et réagir en conséquence. Nous considérons que ces logiciels peuvent bénéficier d'une approche basée sur les Lignes de Produits Logiciels (LPL). Les LPLs sont définies pour exploiter les points communs par la définition d'éléments réutilisables. Néanmoins, les LPLs ne prennent pas en compte les modifications à l'exécution des applications. Cette thèse propose une ligne de produits logiciels dynamique (LPLD) qui étend une LPL classique en fournissant des mécanismes pour adapter les produits à l'exécution. Notre objectif principal est d'unifier les adaptations à la conception et à l'exécution en utilisant des artefacts logiciels de haut niveau. Concrètement, nous introduisons un modèle de variabilité et un modèle de composition pour modulariser les produits sous forme de modèles d'aspect. Chaque modèle d'aspect a trois parties : l'architecture, les modifications, et le point de coupe. Ensuite, nous proposons deux processus de dérivation du produit : un pour la conception que vise à construire un produit, et un pour l'exécution que vise à adapter un produit. Ce travail de recherche s'est déroulé dans le cadre du projet FUI CAPPUCINO. Nous avons défini une LPLD pour une étude de cas de vente d'un hypermarché sensible au contexte. Le scénario démontre les avantages de notre approche et, en particulier, l'unification réalisée par les modèles d'aspect utilisés à la fois à la conception et à l'exécution