Web service composition enhanced by semantic technologies is currently one of the most hyped and addressed issues in Service Oriented Computing. This work focuses on both i) conditional composition, i.e., how to automate the composition of services t

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.

Automation of Web service composition is one of the most interesting challenges facing the Semantic Web today. Since Web services have been enhanced with formal semantic descriptions, it becomes conceivable to exploit causal links i.e., semantic matching between their functional parameters (i.e., outputs and inputs). The semantic quality of causal links involved in a composition can be then used as a innovative and distinguishing criterion to estimate its overall semantic quality. Therefore non functional criteria such as quality of service (QoS) are no longer considered as the only criteria to rank compositions satisfying the same goal. In this paper we focus on semantic quality of causal link based semantic Web service composition. First of all, we present a general and extensible model to evaluate quality of both elementary and composition of causal links. From this, we introduce a global causal link selection based approach to retrieve the optimal composition. This problem is formulated as an optimization problem which is solved using efficient integer linear programming methods. The preliminary evaluation results showed that our global selection based approach is not only more suitable than the local approach but also outperforms the naive approach.

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 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.

The paper introduces a unified formal model for the complete and accurate specification of both temporal and logical (i.e., link) synchronization within hypermedia distributed and weakly synchronous systems. This new model extends time Petri nets with hierarchical design capabilities and new firing rules. These new firing rules enlighten the notion of hypermedia synchronization through powerful combinations of temporal and logical synchronization. Moreover, the proposed model offers an easy and concise modeling technique of asynchronous events in hypermedia systems.