Software components are a valuable programming abstraction that enables a compositional design of complex applications. In distributed systems, components can also be used to provide an abstraction of locations: each component is a unit of deployment that can be placed on a di erent machine. In this article, we consider this kind of distributed components that are additionally loosely coupled and communicate by asynchronous invocations. Components also provide a convenient abstraction for verifying the correct behaviour of systems: they provide structuring entities easing the correctness veri cation. This article aims at providing a formal background for the generation of behavioural semantics for asynchronous components. We use the pNet intermediate language to express the semantics of hierarchical distributed components communicating asynchronously by a request-reply mechanism. We also formalise two crucial aspects of distributed components: recon guration and one-to-many communications. This article both demonstrates the expressiveness of the pNet model and formally speci es the complete process of the generation of a behavioural model for a distributed component system. The behavioural models we build are precise enough to allow veri cation by nite instantiation and model-checking, but also to use veri cation techniques for in nite systems. Key-words: Behavioural speci cation, software components, asynchronous communications, futures Les composants logiciels fournissent une abstraction de programmation intéres-sante pour la conception modulaire d'applications complexes. Dans les systèmes répartis, les composants peuvent également être utilisés pour fournir une abstraction de la localisation des processus: chaque composant est une unité de déploiement qui peut être placée sur une machine di érente. Dans cet article, nous considérons ce type de composants distribuées, faiblement couplés et communiquant par des appels asynchrones.Les composants fournissent également une abstraction commode pour véri er le bon comportement des systèmes: ils fournissent un concept structurant qui facilite la véri cation de ses propriétés. Cet article vise à fournir un support formel pour la génération de la sémantique comportementale des composants asynchrones. Nous utilisons le formalisme intermédiaire pNet pour exprimer la sémantique des composants hiérarchiques distribués communiquant de manière asynchrone par un mécanisme de requêtes. Nous formalisons également deux aspects fondamentaux des composants distribués: la recon guration et les communications de groupe. Cet article d'une part démontre l'expressivité du modèle pNet et d'autre part spéci e formellement le processus complet de la génération du modèle comportemental d'un système de composants distribués. Les modèles de comportement que nous construisons sont su samment précis pour permettre la véri cation par instanciation nie et model-checking, mais aussi pour utiliser des techniques de véri cation de systèmes in nis.

Cloud computing and Future Internet promise a new ecosystem where everything is "as a service", reachable and connectable anywhere and anytime, everyone succeeding to get a service composition that meets his needs. But do we have the structure and the appropriate properties to design the service components and do we have the means to manage, at run-time, the personalised compositions corresponding to Service Level Agreement? In this article we introduce an entity of service composition called Self-Controlled Component (SCC), including, since the design step, functional and non-functional specifications. SCCs benefit both from the strong structure, explicit composition, and autonomic management of component-oriented programming, from the highly dynamic composition, and from the discovery capacities of service-oriented computing. Self-control mechanisms are then attached automatically to SCCs to enable autonomic application management during execution. The objective of this new concept is to provide strong Quality of Service (QoS) guarantees of composed applications. We illustrate the approach using an example called Springoo, to how in the context of a legacy application the contributions and benefits of our solution. For the management of the service composition we propose the concept of Virtual Private Service Network (VPSN) and Virtual Service Community (VSC) that allows us to model the personalised Service Level Agreement (SLA) where user requirements and provider offers converge on a QoS contract.

This article provides formal definitions characterizing well-formed composition of components in order to guarantee their safe deployment and execution. Our work focuses on the structural aspects of component composition; it puts together most of the concepts common to many component models, but never formalized as a whole. Our formalization characterizes correct component architectures made of functional and non-functional aspects, both structured as component assemblies. Interceptor chains can be used for a safe and controlled interaction between the two aspects. Our well-formed components guarantee a set of properties ensuring that the deployed component system has a correct architecture and can run safely. Finally, those definitions constitute the formal basis for our Eclipsebased environment for the development and specification of component-based applications.

International audienceThis paper targets the generation of distributed applications with safety guarantees. The proposed approach starts from graphical specification formalisms allowing the architectural and behavioral description of component systems. From this point, the user can automatically verify application properties using model-checking techniques. Finally, the specified and verified component model can be translated into executable Java code. We implement our approach in a tool suite distributed as an Eclipse plugin. This paper also illustrates our approach by modeling and verifying Peterson's leader election algorithm