Sound Multi-Party Business Protocols for Service Networks

Service networks comprise large numbers of long-running, highly dynamic complex end-to-end service interactions reflecting asynchronous message flows that typically transcend several organizations and span several geographical locations. At the communication level, service network business protocols can be flexible ranging from conventional inter-organizational point-to-point service interactions to fully blown dynamic multi-party interactions of global reach within which each participant may contribute its activities and services. In this paper we introduce a formal framework enriched with temporal constraints to describe multiparty business protocols for service networks. We extend this framework with the notion of multi-party business protocol soundness and show how it is possible to execute a multi-party protocol consistently in a completely distributed manner while guaranteeing eventual termination

A theory and model for the evolution of software services

Software services are subject to constant change and variation. To control service development, a service developer needs to know why a change was made, what are its implications and whether the change is complete. Typically, service clients do not perceive the upgraded service immediately. As a consequence, service-based applications may fail on the service client side due to changes carried out during a provider service upgrade. In order to manage changes in a meaningful and effective manner service clients must therefore be considered when service changes are introduced at the service provider's side. Otherwise such changes will most certainly result in severe application disruption. Eliminating spurious results and inconsistencies that may occur due to uncontrolled changes is therefore a necessary condition for the ability of services to evolve gracefully, ensure service stability, and handle variability in their behavior. Towards this goal, this work presents a model and a theoretical framework for the compatible evolution of services based on well-founded theories and techniques from a number of disparate fields.

A theory and model for the evolution of software services.

Software services are subject to constant change and variation. To control service development, a service developer needs to know why a change was made, what are its implications and whether the change is complete. Typically, service clients do not perceive the upgraded service immediately. As a consequence, service-based applications may fail on the service client side due to changes carried out during a provider service upgrade. In order to manage changes in a meaningful and effective manner service clients must therefore be considered when service changes are introduced at the service provider's side. Otherwise such changes will most certainly result in severe application disruption. Eliminating spurious results and inconsistencies that may occur due to uncontrolled changes is therefore a necessary condition for the ability of services to evolve gracefully, ensure service stability, and handle variability in their behavior. Towards this goal, this work presents a model and a theoretical framework for the compatible evolution of services based on well-founded theories and techniques from a number of disparate fields.

Coordination fiable de services de données à base de politiques actives

We propose an approach for adding non-functional properties (exception handling, atomicity, security, persistence) to services' coordinations. The approach is based on an Active Policy Model (AP Model) for representing services' coordinations with non-functional properties as a collection of types. In our model, a services' coordination is represented as a workflow composed of an ordered set of activities, each activity in charge of implementing a call to a service' operation. We use the type Activity for representing a workflow and its components (i.e., the workflow' activities and the order among them). A non-functional property is represented as one or several Active Policy types, each policy composed of a set of event-condition-action rules in charge of implementing an aspect of the property. Instances of active policy and activity types are considered in the model as entities that can be executed. We use the Execution Unit type for representing them as entities that go through a series of states at runtime. When an active policy is associated to one or several execution units, its rules verify whether each unit respects the implemented non-functional property by evaluating their conditions over their execution unit state, and when the property is not verified, the rules execute their actions for enforcing the property at runtime. We also proposed a proof of concept Active Policy Execution Engine for executing an active policy oriented workflow modelled using our AP Model. The engine implements an execution model that determines how AP, Rule and Activity instances interact among each other for adding non-functional properties (NFPs) to a workflow at execution time. We validated the AP Model and the Active Policy Execution Engine by defining active policy types for addressing exception handling, atomicity, state management, persistency and authentication properties. These active policy types were used for implementing reliable service oriented applications, and mashups for integrating data from services.Nous proposons une approche pour ajouter des propriétés non-fonctionnelles (traitement d'exceptions, atomicité, sécurité, persistance) à des coordinations de services. L'approche est basée sur un Modèle de Politiques Actives (AP Model) pour représenter les coordinations de services avec des propriétés non-fonctionnelles comme une collection de types. Dans notre modèle, une coordination de services est représentée comme un workflow compose d'un ensemble ordonné d'activité. Chaque activité est en charge d'implante un appel à l'opération d'un service. Nous utilisons le type Activité pour représenter le workflow et ses composants (c-à-d, les activités du workflow et l'ordre entre eux). Une propriété non-fonctionnelle est représentée comme un ou plusieurs types de politiques actives, chaque politique est compose d'un ensemble de règles événement-condition-action qui implantent un aspect d'un propriété. Les instances des entités du modèle, politique active et activité peuvent être exécutées. Nous utilisons le type unité d'exécution pour les représenter comme des entités dont l'exécution passe par des différents états d'exécution en exécution. Lorsqu'une politique active est associée à une ou plusieurs unités d'exécution, les règles vérifient si l'unité d'exécution respecte la propriété non-fonctionnelle implantée en évaluant leurs conditions sur leurs états d'exécution. Lorsqu'une propriété n'est pas vérifiée, les règles exécutant leurs actions pour renforcer les propriétés en cours d'exécution. Nous avons aussi proposé un Moteur d'exécution de politiques actives pour exécuter un workflow orientés politiques actives modélisé en utilisant notre AP Model. Le moteur implante un modèle d'exécution qui détermine comment les instances d'une AP, une règle et une activité interagissent entre elles pour ajouter des propriétés non-fonctionnelles (NFP) à un workflow en cours d'exécution. Nous avons validé le modèle AP et le moteur d'exécution de politiques actives en définissant des types de politiques actives pour adresser le traitement d'exceptions, l'atomicité, le traitement d'état, la persistance et l'authentification. Ces types de politiques actives ont été utilisés pour implanter des applications à base de services fiables, et pour intégrer les données fournies par des services à travers des mashups