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2011 | Buch

Semantic Web Services

verfasst von: Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma

Verlag: Springer Berlin Heidelberg

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Über dieses Buch

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.

Inhaltsverzeichnis

Frontmatter

Scientific and Technological Foundations of Semantic Web Services

Frontmatter
Chapter 1. Introduction
Abstract
The principled combination of semantic and service-oriented technologies has been motivated by the need to provide robust and scalable interoperability solutions in both closed and open IT environments. Several research efforts have addressed the formal semantic descriptions of computational artifacts in order to automate their use and reuse in software systems. Based on previous works in formal software specification and knowledge engineering, the latest development in this area is the concept of “Semantic Web Services” (SWS), which foresees the usage of service descriptions via machine-understandable metadata on the basis of domain ontologies as a means to enable their automatic location, execution, combination and usage. This book provides a comprehensive overview of Semantic Web Services in step with the actual practice in the field. It introduces the main socio-technological components that ground the Semantic Web Services vision (Web and service science, but also Web services in their SOAP and REST version) and several approaches realizing it, as well as its recent resource-oriented extensions and underlying communication and coordination infrastructure. The real-world relevance is pinpointed through a series of case studies in large-scale R&D projects from the last years and a business-oriented proposition by the Semantic Web Services technology provider Seekda.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 2. Web Science
Abstract
Originally intended to be a simple way to share and interlink documents over the Internet, the Web has evolved into one of the most complex technologies currently available. This transformation took place in a short period of time, and in a rather chaotic manner, leading to the current lack of structure, security and confidentiality including billions of duplicate information pieces. Thus to overcome such issues, several key researchers contributing to the Web and related sciences are pointing out the need for a new emerging science, the so-called Web Science.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 3. Service Science
Abstract
The goal of Service Science as a discipline is to promote service innovation and increase service productivity. It focuses on accommodating multiple clients and multiple providers’ needs, as well as on the multi-phase business processes.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 4. Web Services
Abstract
One paradigm that changed academic and industrial perspective on how to realize Enterprise Application Integration (EAI) and build distributed applications is Web services. Their emergence is the result of an evolutionary process that started with the introduction of Remote Procedure Call (RPC) and continued with TP Monitors, Object Brokers and Message-Oriented Middleware. The driving concept and innovation behind Web services is the abstraction of functionalities as services hiding the technical realization in terms of hardware and software. In the end, it is the functionality that counts for a client and not the technicalities that realize this functionality. In this chapter, we provide an introduction to Web services. We look at the most important technologies from the Web services technologies landscape. First, the theoretical aspects of these technologies are described including their concepts, definitions and mechanisms. Second, each of the technologies are exemplified by means of practical examples. Finally, we discuss extensions of Web services and provide a set of exercises that should be solved by the reader interested in fixing the concepts and notion presented in this chapter.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 5. Web2.0 and RESTful Services
Abstract
In this chapter, we discuss technologies that can be used to develop and deploy services according to the core principles of the World Wide Web. These new type of services are known as RESTful services. First, we introduce the theoretical aspects of these technologies, including the main concepts, definitions and mechanisms. Second, we illustrate each of them by means of practical examples. In addition, we provide an analytic comparison of RESTful and traditional WSDL-based services which have been discussed in the previous chapter.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 6. Semantic Web
Abstract
This chapter gives an overview of the Semantic Web which aims to enable automatic retrieval, extraction and integration of information on the World Wide Web (WWW). Event though the current Web has become a big success, it lacks a proper support to Web users when it comes to finding, extracting and combining information. The main obstacle is that, at present, the meaning of Web content is not machine-accessible. The Semantic Web extends the current Web providing machine processable semantics to Web resources. This chapter is built around the Semantic Web layered architecture introduced by its inventor, Tim Berners-Lee. Each layer and language of the Semantic Web is described in terms of its major concepts and core aspects. As part of the lower layers of the Web architecture, the chapter introduces Unicode: the Uniform Resource Identifier (URI), the Extensible Markup Language (XML), the Document Type Definition (DTD), and the XML Schema. The chapter then discusses languages that are built on top of the syntactic layers introduced previously, namely the Resource Description Framework (RDF), RDF Schema (RDFS), SPARQL, the Web Ontology Language (OWL), its new version OWL2, and the Rule Interchange Format (RIF). The chapter then briefly reports on the other layers of the Semantic Web architecture and discusses the latest development of the Web and Semantic Web, know as Linked Open Data.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma

Web Service Modeling Ontology Approach

Frontmatter
Chapter 7. Web Service Modeling Ontology
Abstract
This chapter presents the Web Service Modeling Ontology, an ontology for describing various aspects related to Semantic Web Services. WSMO is the major initiative in the area of Semantic Web Services in Europe. The starting point of WSMO was the Web Service Modeling Framework (WSMF) (Fensel and Bussler in Electronic Commerce Research and Applications 1(2):113–137, 2002), which was refined and extended, resulting in (i) a formal ontology, the Web Service Modeling Ontology (WSMO), (ii) a formal family of languages, the Web Service Modeling Language (WSML), and (iii) an execution environment, the Web Service Modeling Environment (WSMX). The four main elements of WSMF have been adopted and refined in WSMO, resulting in four main elements for describing Semantic Web Services: (i) ontologies that provide the terminology used by other elements, (ii) goals that define the problems that should be solved by Web services, (iii) Web services descriptions that define various aspects of a Web service, and (iv) mediators which facilitate the resolution of interoperability problems. WSMO is a key technology needed for the successful realization of Semantic Web Services and Semantically Enabled Service-oriented Architectures. It provides a conceptual model for Semantic Web Services that combines the design principles of the Web, the Semantic Web and distributed service oriented computing in order to provide a clean modeling solution for various aspects related to Semantic Web Services.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 8. The Web Service Modeling Language
Abstract
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.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 9. The Web Service Execution Environment
Abstract
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.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma

Complementary Approaches for Web Service Modeling Ontology

Frontmatter
Chapter 10. Triple Space Computing for Semantic Web Services
Abstract
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.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 11. OWL-S and Other Approaches
Abstract
WSMO is just one of the frameworks to semantically describe Web services that have been developed in the last years. OWL-S and its extension SWSF, as well as METEOR-S, have proposed alternative approaches to WSMO that, despite sharing some similarities, exhibit significant differences with respect to the technological standards, languages and underlying formalisms that are used. This chapter gives an overview of these approaches together with a comparison based on the criteria referring to the core design principles of Web and Semantic Web development, as well as of distributed, service-oriented computing on the Web. In addition, the chapter introduces IRS-III, a framework and implementation infrastructure that, similarly to WSMX, supports the creation of Semantic Web Services based on WSMO ontology.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 12. Lightweight Semantic Web Service Descriptions
Abstract
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.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma

Real-World Adoption of Semantic Web Services

Frontmatter
Chapter 13. What Are SWS Good for? DIP, SUPER, and SOA4All Use Cases
Abstract
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.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Chapter 14. Seekda: The Business Point of View
Abstract
Industry is slowly picking up on the use of semantic technologies within their systems. In this chapter, we describe how these technologies are employed by seekda, a company focused on Web services. The aim of seekda is to ease the search, interoperability and bundling of services and make them readily usable in various areas, for example, in e-Tourism. This is done through the use of a crawler, a search portal and a service bundle creator. An application of these technologies within a seekda product—seekda! connect—is also described.
Dieter Fensel, Federico Michele Facca, Elena Simperl, Ioan Toma
Backmatter
Metadaten
Titel
Semantic Web Services
verfasst von
Dieter Fensel
Federico Michele Facca
Elena Simperl
Ioan Toma
Copyright-Jahr
2011
Verlag
Springer Berlin Heidelberg
Electronic ISBN
978-3-642-19193-0
Print ISBN
978-3-642-19192-3
DOI
https://doi.org/10.1007/978-3-642-19193-0