Federico Michele Facca

Semantic Web Services

A paradigm shift is taking place in computer science: one generation ago, we learned to abstract from hardware to software, now we are abstracting from software to serviceware implemented through service-oriented computing. Yet ensuring interoperability in open, heterogeneous, and dynamically changing environments, such as the Internet, remains a major challenge for actual machine-to-machine integration. Usually significant problems in aligning data, processes, and protocols appear as soon as a specific piece of functionality is used within a different application context. The Semantic Web Services (SWS) approach is about describing services with metadata on the basis of domain ontologies as a means to enable their automatic location, execution, combination, and use. Fensel and his coauthors provide a comprehensive overview of SWS in line with actual industrial practice. They introduce the main sociotechnological components that ground the SWS vision (like Web Science, Service Science, and service-oriented architectures) and several approaches that realize it, e.g. the Web Service Modeling Framework, OWL-S, and RESTful services. The real-world relevance is emphasized through a series of case studies from large-scale R&D projects and a business-oriented proposition from the SWS technology provider Seekda.Each chapter of the book is structured according to a predefined template, covering both theoretical and practical aspects, and including walk-through examples and hands-on exercises. Additional learning material is available on the book website www.swsbook.org. With its additional features, the book is ideally suited as the basis for courses or self-study in this field, and it may also serve as a reference for researchers looking for a state-of-the-art overview of formalisms, methods, tools, and applications related to SWS.

Solving Semantic Interoperability Conflicts in Cross-Border E-Government Services

Interoperability is one of the most challenging problems in modern cross-organizational information systems, which rely on heterogeneous information and process models. Interoperability becomes very important for e-Government information systems that support cross-organizational communication especially in a cross-border setting. The main goal in this context is to seamlessly provide integrated services to the user (citizen). In this paper we focus on Pan European e-Services and issues related with their integration. Our analysis uses basic concepts of the generic public service model of the Governance Enterprise Architecture (GEA) and of the Web Service Modeling Ontology (WSMO), to express the semantic description of the e-services. Based on the above, we present a mediation infrastructure capable of resolving semantic interoperability conflicts at a pan-European level. We provide several examples to illustrate both the need to solve such semantic conflicts and the actual solutions we propose.

WSMX 1.0: A Further Step toward a Complete Semantic Execution Environment

The Web Service Execution Environment (WSMX) project is a continuously ongoing effort that aims at delivering a middleware covering all the Semantic Web Services life cycle. WSMX represents the reference implementation of the Semantically enabled Service Oriented Architecture (SESA) [1]. In this demonstration we aim to present the latest achievements that include: Web Service monitoring, Web Service ranking and Web Service grounding.

The Web Service Modeling Language

Several languages have been developed to describe ontologies, e.g., OWL, KIF, OIL, F-Logic. They have different characteristics and different underlying logics that make them more suitable to certain types of use, e.g., OWL is perfect for describing hierarchies. In some cases, they have been used to describe Semantic Web Services, e.g., OWL-S is an ontology expressed in OWL to describe Semantic Web Services, but they have not been designed with this purpose in mind. In this chapter, we provide an introduction to the Web Service Modeling Language (WSML), a language for the specification of different aspects of Semantic Web Services. First, we discuss the motivation behind the introduction of WSML, then we analyze the WSML language in detail providing examples for each of its constructs. This analysis is followed by a large example showing a fully fledged set of Semantic Web Services descriptions based on WSML. Finally, we provide a set of exercises to practice WSML.

Lightweight Semantic Web Service Descriptions

The Web standardization consortium W3C has developed a lightweight bottom-up specification, Semantic Annotation for WSDL (SAWSDL), for adding semantic annotations to WSDL service descriptions. In this chapter, we describe SAWSDL, and then we present WSMO-Lite and MicroWSMO, two related lightweight approaches to Semantic Web Service description, evolved from the Web Service Modeling Ontology (WSMO) framework. WSMO-Lite defines an ontology for service semantics, used directly in SAWSDL to annotate WSDL-based services. MicroWSMO and its basis, hRESTS, are microformats that supplement WSDL and SAWSDL for unstructured HTML descriptions of services, providing WSMO-Lite support for the growing numbers of RESTful services.

Triple Space Computing for Semantic Web Services

Semantic Web Services promise seamless interoperability of data and applications on a semantic level, thus turning the Web from a world-wide information repository for human consumption only to a device of distributed computation. To this end, appropriate semantic descriptions of Web services and intelligent mechanisms working on this need a solid foundation in terms of the underlying semantically-enabled communication technologies. Recent advances in middleware technologies propose semantics-aware tuplespaces as an instrument for coping with the arising requirements of scalability, heterogeneity and dynamism. An additional argument is that Semantic Web Services have inherited the communication model of XML-based Web services, which is based on message exchange, thus being a priori incompatible with the REST architectural model of the Web. Analogously to the conventional Web, truly Web-compliant service communication should be based on persistent publication instead of message passing. In this chapter, we present “Triple Space computing”, a Triple Space-based coordination middleware for Semantic Web Services. We take a closer look at the respective data, infrastructure and coordination models that enable the management of formal knowledge and that support the interaction patterns characteristic for the Semantic Web and Semantic Web Services. Applying Triple Space computing to Semantic Execution Environments and Service-Oriented Infrastructures is the second main topic of this chapter.

Information systems for enhancing social experience in a conference context: A sensor based approach

We combine Auto Identification and Web technologies in an extensible on-site event support system for enhancing experience of conference organizers as well as participants. Our system enables users to authenticate themselves using RFID badges and to access interactive, Web-based services via a touchscreen PC. The developed services aim at supporting social interactions of participants, and thus validate the promising usage directions of the combination of offline social networks and the online social Web. The main hypothesis of our work is that: “A sensor based information system can truly enhance social conference experience.” Technically, we have investigated employment of Web 2.0 technologies in social, sensor and mobile technologies enabled systems at conferences and events. This article gives an overview of the overall system and its evaluation via a user survey and usage log data collected during the Extended Semantic Web Conference (ESWC) 2010 and similar international conferences, altogether with several hundred participants.

What Are SWS Good for? DIP, SUPER, and SOA4All Use Cases

In this chapter, we present a selection of extensions and use cases for Semantic Web Services from successful European research projects, namely ‘Data, Information, and Process Integration with Semantic Web Services’ (DIP), ‘Semantics Utilized for Process management within and between Enterprises’ (SUPER) and ‘Service Oriented Architectures for All’ (SOA4All). These projects tackle different aspects of Semantic Web Services, and extend the concepts presented so far in the book in different directions. Due to the differing nature of this chapter, rather than following the structure adopted in the previous chapters, we will provide a general overview in the motivation section, and then dedicate a section to each of the aforementioned projects. For each project, we will first introduce the project and provide background motivation behind it; we will then present technology enhancements delivered through the project and contributions to the extension and evolution of Semantic Web Services technologies; finally, we will emphasize one or more use cases adopted in the project to demonstrate how the technology has been adopted. The summary section concludes with a summary of the achievements of these projects.

The Web Service Execution Environment

Computer science is on the edge of an important new period of abstraction. A generation ago we learned to abstract from hardware and currently we learn to abstract from software in terms of Service Oriented Architectures (SOA). A Service Oriented Architecture is essentially a collection of services. However, we believe that these SOAs will not scale without significant mechanization of service discovery, service adaptation, service negotiation, service composition, service invocation, and service monitoring, as well as data-, protocol-, and process-mediation. We envisage the future of applied computer science in terms of service-oriented architectures which is empowered by adding semantics as a means of dealing with heterogeneity and mechanization of service usage. This approach is called Semantically Enabled Service-oriented Architectures, or SESA for short. In this chapter, we give an introduction to SESA and Web Service Execution Environment (WSMX) as its most prominent implementation. First, we are motivating the SESA approach, followed by an analysis of SESA vision, and governing principles. Special attention is paid to the notion of Execution Semantics, basic SESA services and WSMX. The elaboration is followed by a larger example demonstrating steps needed to achieve a WSMO goal.

An extensible system for enhancing social conference experience

We combine Auto-ID and Web technologies in an extensible on-site event support system for enhancing experience of conference organizers as well as participants. Our system enables users to authenticate themselves using RFID badges and to access interactive Web-based services via a touchscreen terminal. The developed services aim at supporting social interactions of participants, and thus validate the promising usage directions of the combination of offline social networks and the online social Web. Technically, we have investigated employment of Web 2.0 technologies in social, sensor and mobile technologies enabled systems at conferences and events. This paper gives an overview of the overall system and its evaluation via a user survey and usage log data collected during the Extended Semantic Web Conference (ESWC) 2010 and similar international conferences, altogether with several hundred participants.