Freddy Lecue

A Framework for Dynamic Web Services Composition

Dynamic composition of web services is a promising approach and at the same time a challenging research area for the dissemination of service-oriented applications. It is widely recognised that service semantics is a key element for the dynamic composition of Web services, since it allows the unambiguous descriptions of a service’s capabilities and parameters. This paper introduces a framework for performing dynamic service composition by exploiting the semantic matchmaking between service parameters (i.e., outputs and inputs) to enable their interconnection and interaction. The basic assumption of the framework is that matchmaking enables finding semantic compatibilities among independently defined service descriptions. We also developed a composition algorithm that follows a semantic graph-based approach, in which a graph represents service compositions and the nodes of this graph represent semantic connections between services. Moreover, functional and non-functional properties of services are considered, to enable the computation of relevant and most suitable service compositions for some service request. The suggested end-to-end functional level service composition framework is illustrated with a realistic application scenario from the IST SPICE project.

Applying Abduction in Semantic Web Service Composition

The semantic web promises to bring automation to the areas of web service selection, discovery, composition, invocation. In this paper we introduce a means of facilitating automation of web service composition by exploiting semantic matchmaking between web service parameters (i.e., outputs and inputs) to enable their connections and interactions. The idea is that matchmaking functions are key components to find semantic compatibilities among independently web service descriptions. To this end, our approach extends existing methods (exact, plug-in, subsume, intersection and fail) with concept abduction to provide explanations of misconnections between web services. From this we generate web service compositions that realize the goal, discovering and satisfying semantic connections between Web services. Moreover a process of relaxing the hard constraints is introduced in case the composition process failed. Our system is implemented and interacting with web services dedicated on a France Telecom scenario.

Semantic Web Service Composition Based on a Closed World Assumption

Automation of Web service composition i.e., the process of forming new value added Web services is one of the most promising challenges in Web service research area. Such an automation does not involve only a richer semantic for Web service description but also reasoning processes about those descriptions. Semantics is supposed to be one of the key elements for the automation of Web service composition. Indeed semantic Web services enable a rich machine-understandable descriptions of their capabilities and processes in order to ease automation of processes such as discovery, selection and composition. In this paper one studies the functional level description of Web services and its impact on Web service composition hence the presentation of a formal model CLM (causal link matrix). The model supports a semantic context in order to find a correct, complete and consistent plan as an AI planning-based composition. The innovative and formal model follows a forward chaining-oriented composition. Moreover two methods of optimization (i.e., local-oriented and a global-oriented) of Web service composition are introduced to discover the best plan according to a semantic criterion i.e., the causal link between Web services

Semantic and Syntactic Data Flow in Web Service Composition

Automation of Web service composition is one of the most interesting challenges facing the Service Oriented Computing today. From this challenge, many issues such as control flow, data flow, verification, execution monitoring, or recovery actions (e.g., compensation) follows. In this paper we focus on automated data flow in Web service composition. The semantic Web, as an evolving extension of the current Web, seems a key initiative to overcome the latter issue. However, even if some approaches focus on discovering potential semantic connections between Web services, few or none of these tackle implementations issues related to XML messages management at syntactic level. In this direction we present an approach for performing automated data flow in Web service composition by i) exploiting semantic matchmaking between Web service parameters (i.e., outputs and inputs) to enable their connection and interaction, and ii) adapting XML database solutions, specifically XML Schema mapping, to perform syntactic data transformation and integration of exchanged messages. Our system is implemented and interacting with Web services dedicated on a Telecom scenario. The preliminary evaluation results showed not only high efficiency and effectiveness of the proposed approach but also complementarity of the semantic matchmaking and syntactic mapping to achieving data flow in Web service composition.

Semantic Web Service Composition through a Matchmaking of Domain

The automated composition of Web services is one of the most promising ideas and at the same time one of the most challenging research area for the taking off of service-oriented applications. It is widely recognised that one of the key elements for the automated composition of Web services is semantics, i.e. unambiguous descriptions of Web services capabilities and processes. However Web services described at capability level need a formal context to perform the automated composition of Web services. In this paper a TLB architecture (three levels based architecture) is presented to perform Web service composition. Moreover we introduce the composition process as a matchmaking of domains and solve the latter problem according to a formal model, i.e. the xCLM (eXtended causal link matrix) and a knowledge base of the domain

Web service composition as a composition of valid and robust semantic links

Automated composition of Web services or the process of forming new value-added Web services is one of the most promising challenges facing the Semantic Web today. Semantics enables Web service to describe capabilities together with their processes, hence one of the key elements for the automated composition of Web services. In this paper, we focus on the functional level of Web services i.e. services are described according to some input, output parameters semantically enhanced by concepts in a domain ontology. Web service composition is then viewed as a composition of semantic links wherein the latter links refer to semantic matchmaking between Web service parameters (i.e. outputs and inputs) in order to model their connection and interaction. The key idea is that the matchmaking enables, at run time, finding semantic compatibilities among independently defined Web service descriptions. By considering such a level of composition, a formal model to perform the automated composition of Web services i.e. Semantic Link Matrix, is introduced. The latter model is required as a starting point to apply problem-solving techniques such as regression (or progression)-based search for Web service composition. The model supports a semantic context in order to find correct, complete, consistent and robust plans as solutions. In this paper, an innovative and formal model for an AI (Artificial Intelligence) planning-oriented composition is presented. Our system is implemented and interacting with Web services which are dedicated to Telecom scenarios. The preliminary evaluation results showed high efficiency and effectiveness of the proposed approach.

Integrating Discovery and Automated Composition: from Semantic Requirements to Executable Code

Web services are conveniently advertised and published based on (stateless) functional descriptions, while they are usually realized as (stateful) processes. Therefore, the automated enactment of complex Web services on the basis of pre-existing ones requires the ability to handle services described at very different abstraction levels. This is the main reason behind the current lack of approaches capable to perform automated end-to-end composition, starting from semantic requirements to obtain executable orchestrations of stateful processes. In this paper we achieve such a challenging goal, by modularly integrating a range of incrementally more complex techniques that cover the necessary discovery and composition phases. By gradually bridging the gap between the high-level requirements and the concrete realization of services, our architecture manages sensibly the complexity of the problem: incrementally more complex techniques are provided with incrementally more focused input. The tests of our architecture on a deployed scenario witness the functionality of the platform and its integrability with standard service engines.

Les web services semantiques, automate et integration I. Introduction, elements et scenarios, decouverte de services web

Les avancees recentes des technologies « NTIC » (Nouvelles Technologies de l’Information et des Telecommunications) ont (re)-ouvert la voie a de nouvelles solutions pour le developpement d’architectures de traitement distribue dont l’impact industriel et commercial semble cette fois tres prometteur. En effet, la conjonction de la maturite des architectures logicielles a composants distribues, la tres forte penetration des technologies du Web et enfin la forte pression de l’economie mondiale ont conduit a une irresistible proliferation de composants physiques ou logiciels autonomes disponibles et distribues sur le web. Le W3C les definit comme des « services web » : « le service web est un systeme logiciel concu pour rendre interoperable la communication de Machine a Machine connectees en reseaux. Il est decrit par une interface (WSDL) et peut interagir avec d’autres systemes par l’envoi de messages (SOAP) typiquement vehicules par un protocole HTTP et une representation syntaxique XML conjointement a d’autres standards du Web ». Une tres importante fonctionnalite de ces systemes a base de services web est leur capacite a offrir des services composites construits a partir de ces composants physiques ou logiciels autonomes et reutilisables, formant une nouvelle infrastructure de traitement informatique distribue sur le Web. Profitant de l’infrastructure du web semantique, les services web dits « semantiques » ouvrent des perspectives d’avancees cles dans le traitement d’information couvrant un large spectre d’applications comme les services commerciaux (e-Enterprise, e-Business), la recherche scientifique (ex. grille de calcul « e-Science »), l’education (e-Learning) et enfin les services aux citoyens (e-Government, e-Democracy). Nous presentons dans ce tutoriel (en deux parties) un etat de l’art synthetique des langages et technologies associes aux services web semantiques, un panorama detaille des raisonnements de decouverte existants et des solutions majeures pour la composition de services web, pour terminer sur des exemples d’applications et une feuille de route.

Les web services sémantiques, automate et intégration II. Composition de services web, technologies et plateformes, applications industrielles

Recent advances in networks, information and computation grids, and WWW have resulted in the proliferation of a multitude of physically distributed and autonomously developed Web services. This second part presents two key scenarios in B2B and B2C, the central function of services composition and orchestration, the languages and prominent technologies and lastly an industry and research roadmap.