Détection de la terminaison: un algorithme fondé sur une approche observationnelle

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The Design of GCCL: a Generalized Common Contract Language

Following its inception in Eiffel by Meyer and its diffusion to other environments (e.g., the standardisation of OCL as part of UML), Design by Contract now faces a major challenge in component-based software engineerin- g (CBSE). Compositional reasoning about system properties from component ones has been recently asserted by the SEI as the "key technical challenge" of CBSE, and contracts as a "key technical concept to support this vision". To live up to these expectations, DbC must tackle extra-functional properties of components and support Klein's "architectural-based attribute reasoning." Besides adopting the necessary new concepts, a good contract language must provide for abstraction, application, composition and scoping mechanisms in such a way to be used from modeling in UML to programming in standard languages (as seamless extensions to Java, C#, C++, Eiffel, and so on) through execution on traditional operating systems with minimal middleware additions. This paper examines conceptual foundations and design decisions to propose GCCL, a novel open generalized common contract language. GCCL is meant to be compatible with existing DbC (sub)languages, and especially OCL

Elements for a course om design of distributed algorithms

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Évaluation de l'apport des aspects, des sujets et des vues pour la composition et la réutilisation des modèles

National audienceThe reuse, the evolution or the fast adaptation of the code of an application are among the strongest concerns of companies. Model engineering tries to bring a solution putting the model in the center of the software development and by capturing the business know-how initially described in the code of the application. This approach has the advantage to make the description independant of software platforms. Our objective in this paper is to present three different approaches for the composition of models, to evaluate them using the criteria proposed by the AOSD-EUROPE network of excellence in order to extract relevant information. From this evaluation, this paper provides new proposals. The evaluation aims at showing the capacity of each approach to support the composition of both functional and extra-functional concerns

Kevoree Modeling Framework (KMF): Efficient modeling techniques for runtime use

The creation of Domain Specific Languages(DSL) counts as one of the main goals in the field of Model-Driven Software Engineering (MDSE). The main purpose of these DSLs is to facilitate the manipulation of domain specific concepts, by providing developers with specific tools for their domain of expertise. A natural approach to create DSLs is to reuse existing modeling standards and tools. In this area, the Eclipse Modeling Framework (EMF) has rapidly become the defacto standard in the MDSE for building Domain Specific Languages (DSL) and tools based on generative techniques. However, the use of EMF generated tools in domains like Internet of Things (IoT), Cloud Computing or Models@Runtime reaches several limitations. In this paper, we identify several properties the generated tools must comply with to be usable in other domains than desktop-based software systems. We then challenge EMF on these properties and describe our approach to overcome the limitations. Our approach, implemented in the Kevoree Modeling Framework (KMF), is finally evaluated according to the identified properties and compared to EMF.Comment: ISBN 978-2-87971-131-7; N° TR-SnT-2014-11 (2014

A Process for Continuous Validation of Self-Adapting Component Based Systems

International audienceIn this paper we propose an approach to integrate the use of time-related stochastic properties in a continuous design process based on models at runtime. Time-related specifica-tion of services are an important aspect of component-based architectures, for instance in distributed, volatile networks of computation nodes. The models at runtime approach eases the management of such architectures by maintaining abstract models of architectures synchronized with the physical, distributed execution platform. For self-adapting systems, prediction of delays and throughput of a component assembly is of utmost importance to take adaptation decision and accept evolutions that conform to time specifications. To this aim we define a metamodel extension based on stochastic Petri nets as an internal time model for prediction. We design a library of patterns to ease the specification and prediction of common time properties of models at runtime and make the synchronization of behaviors and structural changes easier. Our prediction engine is fast enough to perform prediction at runtime in a realistic setting and validate models at runtime

Kevoree (Model@Runtime pour le développement continu de systèmes adaptatifs distribués hétérogènes)

La complexité croissante des systèmes d'information modernes a motivé l'apparition de nouveaux paradigmes (objets, composants, services, etc), permettant de mieux appréhender et maîtriser la masse critique de leurs fonctionnalités. Ces systèmes sont construits de façon modulaire et adaptable afin de minimiser les temps d'arrêts dus aux évolutions ou à la maintenance de ceux-ci. Afin de garantir des propriétés non fonctionnelles (par ex. maintien du temps de réponse malgré un nombre croissant de requêtes), ces systèmes sont également amenés à être distribués sur différentes ressources de calcul (grilles). Outre l'apport en puissance de calcul, la distribution peut également intervenir pour distribuer une tâche sur des nœuds aux propriétés spécifiques. C'est le cas dans le cas des terminaux mobiles proches des utilisateurs ou encore des objets et capteurs connectés proches physiquement du contexte de mesure. L'adaptation d'un système et de ses ressources nécessite cependant une connaissance de son état courant afin d'adapter son architecture et sa topologie aux nouveaux besoins. Un nouvel état doit ensuite être propagé à l'ensemble des nœuds de calcul. Le maintien de la cohérence et le partage de cet état est rendu particulièrement difficile à cause des connexions sporadiques inhérentes à la distribution, pouvant amener des sous-systèmes à diverger. En réponse à ces défi scientifiques, cette thèse propose une abstraction de conception et de déploiement pour systèmes distribués dynamiquement adaptables, grâce au principe du Model@Runtime. Cette approche propose la construction d'une couche de réflexion distribuée qui permet la manipulation abstraite de systèmes répartis sur des nœuds hétérogènes. En outre, cette contribution introduit dans la modélisation des systèmes adaptables la notion de cohérence variable, permettant ainsi de capturer la divergence des nœuds de calcul dans leur propre conception. Cette couche de réflexion, désormais cohérente "à terme", permet d'envisager la construction de systèmes adaptatifs hétérogènes, regroupant des nœuds mobiles et embarqués dont la connectivité peut être intermittente. Cette contribution a été concrétisée par un projet nommé ''Kevoree'' dont la validation démontre l'applicabilité de l'approche proposée pour des cas d'usages aussi hétérogènes qu'un réseau de capteurs ou une flotte de terminaux mobiles.The growing complexity of modern IT systems has motivated the development of new paradigms (objects, components, services,...) to better cope with the critical size of their functionalities. Such systems are then built as a modular and dynamically adaptable compositions, allowing them to minimise their down-times while performing evolutions or fixes. In order to ensure non-functional properties (i.e. request latency) such systems are distributed across different computation nodes. Besides the added value in term of computational power (cloud), this distribution can also target nodes with dedicated properties such as mobile nodes and sensors (internet of things), physically close to users for interactions. Adapting a system requires knowledge about its current state in order to adapt its architecture to its evolving needs. A new state must be then disseminated to other nodes to synchronise them. Maintaining its consistency and sharing this state is a difficult task especially in case of sporadic connexions which lead to divergent state between sub-systems. To tackle these scientific problems, this thesis proposes an abstraction to design and deploy distributed adaptive systems following the Model@Runtime paradigm. From this abstraction, the proposed approach allows defining a distributed reflexive layer to manipulate heterogeneous distributed nodes. In particular, this contribution introduces variable consistencies in model definition and divergence in system conception. This reflexive layer, eventually consistent allows the construction of distributed adapted systems even on mobile nodes with intermittent connectivity. This work has been realized in an open source project named Kevoree, and validated on various distributed systems ranging from sensor networks to cloud computing.RENNES1-Bibl. électronique (352382106) / SudocSudocFranceF

Expression qualitative de politiques d'adaptation pour Fractal

National audienceLes plates-formes d'exécution récentes telles que Fractal ou Open- COM offrent de nombreuses facilités pour assurer la prise en compte de propriétés extra-fonctionnelles (introspection, sondes, chargement dynamique, etc). Cependant, l'intégration de politiques d'adaptation reste délicate car elle nécessite de corréler la configuration du système avec l'évolution de son environnement. Le travail présenté dans cet article propose une description qualitative des évolutions de l'environnement et une interprétation possible basée sur de la logique floue. L'article présente également une extension de la plate-formeFractal implémentant les mécanismes nécessaires à l'exécution de ces politiques d'adaptation de haut niveau. L'approche est illustrée à l'aide d'un serveur HTTP qui modifie sa configuration (architecturale et locale) en fonction de plusieurs paramètres extra-fonctionnels tels que la charge du serveur et la dispersion des requêtes

Software Diversity: Challenges to handle the imposed, Opportunities to harness the chosen

National audienceDiversity emerges as a critical concern that spans all activities in software engineering (from design to verification, from deployment to runtime resilience) and appears in all sorts of domains, which rely on software intensive systems, from systems of systems to pervasive combinations of Internet of Things and Internet of Services. If these domains are apparently radically different, we envision a strong convergence of the scientific principles underpinning their construction and validation towards flexible and open yet dependable systems. In this paper, we discuss the software engineering challenges raised by these requirements for flexibility and openness, focusing on four dimensions of diversity: the diversity of functionalities required by the different customers; the diversity of languages used by the stakeholders involved in the construction of these systems; the diversity of runtime environments in which software has to run and adapt; the diversity of failures against which the system must be able to react. In particular, we want to emphasize the challenges for handling imposed diversity, as well as the opportunities to leverage chosen diversity. The main challenge is that software diversity imposes to integrate the fact that software must adapt to changes in the requirements and environment -- in all development phases and in unpredictable ways. Yet, exploiting and increasing software diversity is a great opportunity to allow the spontaneous exploration of alternative software solutions and proactively prepare for unforeseen changes. Concretely, we want to provide software engineers with the ability: to characterize an 'envelope' of possible variations; to compose 'envelopes' (to discover new macro envelopes in an opportunistic manner); to dynamically synthesize software inside a given envelop