Alain Léger

On automating Web services discovery

Abstract.One of the challenging problems that Web service technology faces is the ability to effectively discover services based on their capabilities. We present an approach to tackling this problem in the context of description logics (DLs). We formalize service discovery as a new instance of the problem of rewriting concepts using terminologies. We call this new instance the best covering problem. We provide a formalization of the best covering problem in the framework of DL-based ontologies and propose a hypergraph-based algorithm to effectively compute best covers of a given request. We propose a novel matchmaking algorithm that takes as input a service request (or query) Q and an ontology

Applying Abduction in Semantic Web Service Composition

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Semantic Web Service Composition Based on a Closed World Assumption

of services and finds a set of services called a “best cover” of Q whose descriptions contain as much common information with Q as possible and as little extra information with respect to Q as possible. We have implemented the proposed discovery technique and used the developed prototype in the context of the Multilingual Knowledge Based European Electronic Marketplace (MKBEEM) project.

Semantic Web Service Composition through a Matchmaking of Domain

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.

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

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

DL Reasoning and AI Planning for Web Service Composition

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

An Ontology-based Mediation Architecture for E-commerce Applications

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.

Towards the composition of stateful and independent semantic web services

We claim that a key feature for correct and effective web service composition, and one that has largely been ignored,is the joint consideration of (semantic) causal links and causal laws, respectively in area of description logics (DL) and AI planning. In this paper we propose a means of specifying both causal links and laws into Web service composition by integrating DL reasoning and situation calculus. To this end an augmented and adapted version of the logic programming language Golog i.e., sclGolog is presented as a natural formalism not only for reasoning about the latter links and laws, but also for automatically composing services. sclGolog operates as an offline interpreter that supports n-ary sensing actions to retrieve conditional compositions of services. Lastly sclGolog has been implemented and tested in the context of telecommunication scenarios.

The Semantic Web from an Industry Perspective

As part of the MKBEEM project, we present an ontology based mediation framework for electronic commerce applications. The framework is based on a mediator /wrapper approach that supports an integrated view over multiple heterogeneous sources. The MKBEEM mediation system allows to fill the gap between customers queries (possibly expressed in a natural language) and diverse specific providers offers. In contrast with many existing mediator based systems, our approach rests on a three-layer knowledge representation architecture which includes an electronic services ontology besides the usual domain ontology and sources descriptions layers. At the reasoning level, we propose a new mechanism, namely dynamic discovery of e-services, that acts in collaboration with the Picsel mediator system to effectively achieve the MKBEEM mediation tasks.

Self-Organization and Learning in MultiAgent Based Brokerage Services

Most of the work on automated semantic Web service composition has focused so far on two main levels of composition i.e., functional level and process level composition (respectively FLC and PLC from now). The former level of composition considered Web services as atomic components that can be executed in a single request-response step whereas the latter level studies in more details the protocol and the behavioural features of Web services. Since PLC i.e., a time and particularly space consuming level of composition makes difficult the scalability of composition-based applications, it seems interesting to restrict the composition of stateful but (only) independent Web services. Such a restriction make possible the composition of a large number of Web services in industrial scenarios, the whole with convincing results. In this paper we suggest to study the advantages to apply FLC together with β-composition in order to perform an automated end to end composition of stateful and independent services. In particular we focus on computational complexity results concerning the two models of composition i.e., the well-known PLC vs. the newest FLC+β-composition. Moreover we prove that FLC is an interesting and necessary level of composition to significantly reduce computational complexity not only in space but also in time.