Dynamic orchestration of distributed services on interactive community displays: the ALIVE approach

Interconnected service providers constitute a highly dynamic, complex, distributed environment. Multi-agent system design-methodologies have been try-ing to address this kind of environments for a long time. The European project ALIVE presents a framework of three interconnected levels that tackles this issue relying on organisation and coordination techniques, as well as on developments in the Web-services world. This paper presents initial results focused on a high-tech, real use case: interactive community displays with touristic information and services, dynamically personalized according to user preferences and local laws.Peer ReviewedPreprin

Test of several approaches for the composition of web services in meteorology.

International audienceComposition of web services is a powerful means to answer user needs in many domains. This communication focuses on applications in meteorology. This domain presents several particularities which are discussed. We present an overview of three main types of approaches in composition of web services: static plan, IA-plan and theorem proof. We confront these types of approaches to the specific case of meteorology which is not well studied by the research community in web services. We design a test bed that is capable of handling the key issues in meteorology. We have selected three approaches. We adapt them to our case and build three prototypes which are used in the test bed to point out weakness and strength of each approach. We find that current approaches do not fulfill needs in meteorology. We recommend an hybrid approach that combines the three in order to obtain an automatic and adaptative composition

A theorem proving framework for the formal verification of Web Services Composition

We present a rigorous framework for the composition of Web Services within a higher order logic theorem prover. Our approach is based on the proofs-as-processes paradigm that enables inference rules of Classical Linear Logic (CLL) to be translated into pi-calculus processes. In this setting, composition is achieved by representing available web services as CLL sentences, proving the requested composite service as a conjecture, and then extracting the constructed pi-calculus term from the proof. Our framework, implemented in HOL Light, not only uses an expressive logic that allows us to incorporate multiple Web Services properties in the composition process, but also provides guarantees of soundness and correctness for the composition.Comment: In Proceedings WWV 2011, arXiv:1108.208

The pragmatic proof: hypermedia API composition and execution

Machine clients are increasingly making use of the Web to perform tasks. While Web services traditionally mimic remote procedure calling interfaces, a new generation of so-called hypermedia APIs works through hyperlinks and forms, in a way similar to how people browse the Web. This means that existing composition techniques, which determine a procedural plan upfront, are not sufficient to consume hypermedia APIs, which need to be navigated at runtime. Clients instead need a more dynamic plan that allows them to follow hyperlinks and use forms with a preset goal. Therefore, in this paper, we show how compositions of hypermedia APIs can be created by generic Semantic Web reasoners. This is achieved through the generation of a proof based on semantic descriptions of the APIs' functionality. To pragmatically verify the applicability of compositions, we introduce the notion of pre-execution and post-execution proofs. The runtime interaction between a client and a server is guided by proofs but driven by hypermedia, allowing the client to react to the application's actual state indicated by the server's response. We describe how to generate compositions from descriptions, discuss a computer-assisted process to generate descriptions, and verify reasoner performance on various composition tasks using a benchmark suite. The experimental results lead to the conclusion that proof-based consumption of hypermedia APIs is a feasible strategy at Web scale.Peer ReviewedPostprint (author's final draft

An Integrated Declarative Approach to Web Services Composition and Monitoring

International audienceIn this paper we propose a constraint based declarative approach for Web services composition and monitoring problem. Our approach allows user to build the abstract composition by identifying the participating entities and by providing a set of constraints that mark the boundary of the solution. Different types of constraints have been proposed to handle the composition modeling and monitoring. Abstract composition is then used for instantiating the concrete composition, which both finds and executes an instantiation respecting constraints, and also handles the process run-time monitoring. When compared to the traditional approaches, our approach is declarative and allows for the same set of constraints to be used for composition modeling and monitoring and thus allows for refining the abstract composition as a result of run-time violations, such as service failure or response time delays

Rule-Based Semi Automatic Web Services Composition

ISBN-978-0-7695-3708-5International audienceIn this paper we propose a rule-based approach for the semi-automatic Web services composition problem, giving end-user the control to guide the overall composition process. The end-user builds the composition flow by selecting known Web service instances or constrained Web service types, called nodes, and by connecting them using a set of control/data flow connectors. The specified nodes will then be bound to concrete Web service instances using a set of rule-based queries satisfying the associated constraints. When compared to the traditional approaches, our model is declarative, allows for specifying both the functional and non-functional requirements, provides connectors that include both the data and control flow aspects and aims to choose the one best matched Web service for a node instantiation

A MULTI-FUNCTIONAL PROVENANCE ARCHITECTURE: CHALLENGES AND SOLUTIONS

In service-oriented environments, services are put together in the form of a workflow with the aim of distributed problem solving. Capturing the execution details of the services' transformations is a significant advantage of using workflows. These execution details, referred to as provenance information, are usually traced automatically and stored in provenance stores. Provenance data contains the data recorded by a workflow engine during a workflow execution. It identifies what data is passed between services, which services are involved, and how results are eventually generated for particular sets of input values. Provenance information is of great importance and has found its way through areas in computer science such as: Bioinformatics, database, social, sensor networks, etc. Current exploitation and application of provenance data is very limited as provenance systems started being developed for specific applications. Thus, applying learning and knowledge discovery methods to provenance data can provide rich and useful information on workflows and services. Therefore, in this work, the challenges with workflows and services are studied to discover the possibilities and benefits of providing solutions by using provenance data. A multifunctional architecture is presented which addresses the workflow and service issues by exploiting provenance data. These challenges include workflow composition, abstract workflow selection, refinement, evaluation, and graph model extraction. The specific contribution of the proposed architecture is its novelty in providing a basis for taking advantage of the previous execution details of services and workflows along with artificial intelligence and knowledge management techniques to resolve the major challenges regarding workflows. The presented architecture is application-independent and could be deployed in any area. The requirements for such an architecture along with its building components are discussed. Furthermore, the responsibility of the components, related works and the implementation details of the architecture along with each component are presented

COORDINATION ADAPTATIVE DE SERVICES A BASE DE CONTRATS

This thesis presents an approach for the adaptation of contract-based service coordination. The approach proposes the dynamic adaptation operations: the re-invocation of a service method, the substitution of service methods and the substitution of activities. These operations allow adapting the exceptions during the execution of a coordination to guarantee its execution successfully. The main contribution of this thesis is the model of contract-based dynamic service coordination. For the adaptation of coordination, it model provides: - Concepts of classification of methods which allows o define the equivalent methods and the mappings between their interfaces (inputs, outputs) to solve its incompatibilities and, - Concept of adaptability contract which allows explicitly specifying the reactions reacting to the exceptions specified by guaranteeing QoS required.Cette thèse présente une approche pour l'adaptation d'une coordination de services à base de contrats d'adaptabilité. L'approche propose des opérations d'adaptation dynamiques: la réexécution d'un appel d'une méthode de service, la substitution de méthodes de service et la substitution d'activités. Ces opérations permettent de s'adapter aux exceptions lors de l'exécution d'une coordination et de continuer son exécution avec succès. La principale contribution de cette thèse est le modèle de coordination adaptative de services à base de contrats d'adaptabilité. Pour l'adaptation d'une coordination, ce modèle fournit : - les concepts de classification de méthodes qui permettent aux concepteurs de domaines d'application de définir les méthodes équivalentes et les mappings entre leurs entrées et sorties pour résoudre ses incompatibilités et, - la notion de contrat d'adaptabilité qui permet aux concepteurs d'application de spécifier explicitement les réactions réagissant aux exceptions spécifiées en garantissant la QoS exigée