Abstract. The automatic location of services that fulfill a given need is seen as a key step towards dynamic and scalable integration. In this paper we present a model for the automatic location of services that considers the static and dynamic aspects of service descriptions and identifies what notions of match and techniques are useful for the matching of both. Our model presents three important features: ease of use for the requester, efficient pre-filtering of relevant services, and accurate contracting of services that fulfill a given requester goal. We further elaborate previous work and results on Web service discovery by analyzing what steps and what kind of descriptions are necessary for an efficient and usable automatic service location. Furthermore, we analyze the intuitive and formal notions of match that are of interest for locating services that fulfill a given goal. Although having a formal underpinning, the proposed model does not impose any restrictions on how to implement it for specific applications, but proposes some useful formalisms for providing such implementation. 1

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Abstract. Current technologies for Web Services are based on syntactical descriptions and, therefore, lend themselves to only limited amount of automation. Research efforts in Semantic Web Services, such as WSMO, try to overcome this major deficiency by providing a complete semantic description for Web Services and their related aspects. In this paper we present a logical framework which exploits such formal descriptions in order to dynamically discover Web Services that match requester goals. We consider two kinds of user goals: discovery and contracting. Based on the WSMO conceptual model, we define proof obligations that formalize the concepts of a match in these two cases. We also describe a concrete realization of this framework in the F-Logic reasoning engine F LORA-2. Such a realization requires an extension of F-Logic in order to support rule reification. With this extension, F-logic becomes a suitable framework for describing and reasoning about Semantic Web Services and their capabilities. 1

Abstract. We present and motivate a formal approach and algorithms for semantic matchmaking in an e-commerce framework. The proposed solution exploits nonmonotonic inferences to compute semantic-based ranking of offers and provides explanation services in the query-retrievalrefinement loop. 1

A major challenge for Service-oriented Computing is how to discover and compose (Web) services to build complex applications. We present a matchmaking system that exploits both semantics and behavioural information to discover service compositions capable of satisfying a client request.

Abstract. Automatizing the Web Service Discovery is crucial for truly implementing a Service Oriented Architecture. Semantics has been shown to be useful. Several initiative, namely OWL-S, WSMO and WSDL-S, are successfully employing ontologies, but we believe that WSMO is right in highlighting mediation as the missing element. In this paper we provide a mediator centric re nement of the conceptual model for WSMO discovery and the related architecture as well as the prototypical implementation (named Glue) we are using in the projects COCOON and Nomadic Media. 1

Web services are about the integration of applications via the web. Hereby, the programming effort should be minimized through the reuse of standardized components and interfaces. Semantic web services try to provide the next step through mechanizing important sub tasks within a service-oriented architecture. Otherwise, significant manual programming effort would remain as a bottleneck for this approach. One of the sub tasks in a service-oriented architecture is service discovery. While a significant number of papers have already been published in this area, most of them are more concerned in providing yet another illustration for an arbitrary logical framework rather than providing a contribution that meets current constraints in given practical settings. In this paper, we first provide an empirical enumeration of existing approaches towards web service discovery. This sets the basis for analyzing the strengths and weaknesses of the existing approaches as well as the prediction of future potential improvements in this area. We also identify a useful role for semantic techniques as long as it is

We propose a framework and polynomial algorithms for semantic-based automated Web service composition, fully compliant with Semantic Web technologies. The approach exploits the recently proposed Concept Abduction inference service in Description Logics to extend Concept covering definition to expressive logics and to solve Concept Covering problems in a significant subset of OWL-DL. We show how the proposed approach also deals with not-exact solutions, computing an approximate composition and providing an explanation of which part of the request is not covered by the composite service. We present the formalization of the approach, the proposed algorithms, a prototype system implementing the approach, and illustrate experiments carried out with it. KEY WORDS:

Abstract. Ontologies play a relevant role to support service matchmaking in the discovery process. In fact, the elements used for service capability description refer to concepts that can be properly defined and semantically related in domain ontologies. Semantic relationships between concepts are then exploited to establish the type of matching between advertisements and requests. In this paper we propose an ontologybased approach to service discovery characterized by a hybrid multimode matching, that is, a deductive capability matching extended with a flexible similarity evaluation scheme. In the approach, the semantic service description results from the cooperation of several components: a UDDI registry is responsible for managing offered service descriptions, a Domain Ontology provides the general knowledge about concepts from the business domain in which services are used, a Service Ontology organizes services at different levels of abstraction. The proposed approach provides service advice at multiple levels of granularity and rates adviced services according to different kinds of comparison strategies. 1

Abstract With the evolution of Web service technology, services will not only become increasingly sophisticated, but also move into the area of business-to-consumer and peer-to-peer interactions. Because of todays wide variety of services offered to perform a specific task, there is a need for mediation infrastructures able to support humans or agents in the eventual selection of appropriate services. It is a common opinion that such issues should be solved adopting semantically rich unambiguous descriptions. Hence, ontologies should be used to describe services, to ease their discovery and selection. In order to perform such a selection, a matchmaking procedure, based on semantic descriptions similarity, is needed. Technologies developed for the Semantic Web based on theoretical studies on Artificial Intelligence, particularly on Description Logics, can help in this sense. As the Semantic Web is conceived as an extension of the current one, technologies developed explicitly for they both must be used synergically in order to provide a semantic layer to approaches such as UDDI registries, using OWL formatted descriptions. In this paper we present a framework for discovery of services, stored in an UDDI registry, which exposes a description whose semantic can be modeled using OWL-DL based formalism. In order to perform this task, methodologies to compute semantic differences between two descriptions and non-standard inference services have been investigated and exploited in an implemented system. 1.