Semantic Web Services Fundamentals

4th International conference on Web and Information Technologies (ICWIT 2012), Sidi Bel Abbes, Algeria, 2012

Web services are the latest attempt to revolutionize large scale distributed computing. They are based on standards which operate at the syntactic level and lack semantic representation capabilities. Semantics provide better qualitative and scalable solutions to the areas of service interoperation, service discovery, service composition, and process orchestration. SAWSDL defines a mechanism to associate semantic annotations with Web services that are described using Web Service Description Language (WSDL). In this paper we propose an approach for semi-automatically annotating WSDL Web services descriptions. This allows SAWSDL Semantic Web Service Engineering. The annotation approach consists of two main processes: Categorization and Matching. Categorization process consists in classifying WSDL service description to its corresponding domain. Matching process consists in mapping WSDL entities to pre-existing domain ontology. Both categorization and matching rely on ontology matching techniques. A tool has been developed and some experiments have been carried out to evaluate the proposed approach.

Handbook of Semantic …, 2010

In recent years service-orientation has increasingly been adopted as one of the main approaches for developing complex distributed systems out of reusable components called services. Realizing the potential benefits of this software engineering approach requires semi-automated and automated techniques and tools for searching or locating services, selecting the suitable ones, composing them into complex processes, resolving heterogeneity issues through process and data mediation, and reduce other tedious yet recurrent tasks with minimal manual effort. Just as semantics has brought significant benefits to search, integration and analysis of data, semantics is also seen as a key to achieving a greater level of automation to service orientation. This has lead to research and development, as well as standardization efforts on semantic Web services. Activities related to semantic Web services have involved developing conceptual models or ontologies, algorithms and engines that could support machines in semi-automatically or automatically discovering, selecting, composing, orchestrating, mediating and executing services. This chapter provides an overview of the area after nearly a decade of research. The main principles and conceptual models proposed thus far including OWL-S, WSMO, and SAWSDL/METEOR-S. The main approaches developed by the research community that are able to use these semantic descriptions of services to support some of the typical activities related to services and service-based applications are described. Next, the ideas and techniques described through two applications that integrate semantic Web services technologies within real-world application are illustrated. Finally, a set of key resources is provided that would allow the reader to reach a greater understanding of the field, and are the main issues that will drive the future of semantic Web services.

2006

With the expanse of internet, web programmers have wide choice of web services available to them. A need arises for automatic discovery of required web services and construction of an appropriate sequence of invocation thereof. In this paper, we present a framework for automation of this task based on currently emerging technologies such as ontological knowledge bases, OWL, OWL-S, WSDL, Description Logic (DL), etc. Background-knowledge ontologies are created based on which semantic meanings of web services can be given through OWL-S. An agent em- ploys OWL-S API to extract web service metadata, and applies a DL inference engine, called Racer, for reasoning with the metadata with respect to given background knowledge. Reasoning tasks performed by Racer include profile matchmaking, input/output subsumption testing, and preconditions/ee cts anal-

2007

Service-oriented computing is gaining wider acceptance.For Web services to become practical, an infrastructure needs to be supported that allows users and applications to discover, deploy, compose and synthesize services automatically. For this automation to be effective, formal semantic descriptions of Web services should be available. In this paper we formally define the Web service discovery and composition problem and present an approach for automatic service discovery and composition based on semantic description of Web services. We also report on an implementation of a semantics-based automated service discovery and composition engine that we have developed. This engine employs a multi-step narrowing algorithm and is efficiently implemented using the constraint logic programming technology. The salient features of our engine are its scalability, i.e., its ability to handle very large service repositories, and its extremely efficient processing times for discovery and composition queries. We evaluate our algorithms for automated discovery and composition on repositories of different sizes and present the results.

Journal of Web Semantics, 2003

In this paper, we introduce a vision for Semantic Web services which combines the growing Web services architecture and the Semantic Web and we will propose DAML-S as a prototypical example of an ontology for describing Semantic Web services. Furthermore, we show that DAML-S is not just an abstract description, but it can be efficiently implemented to support capability matching and to manage interaction between Web services. Specifically, we will describe the implementation of the DAML-S/UDDI Matchmaker that expands on UDDI by providing semantic capability matching, and we will present the DAML-S Virtual Machine that uses the DAML-S Process Model to manage the interaction with Web service. We will also show that the use of DAML-S does not produce a performance penalty during the normal operation of Web services.

Journal of Web Semantics, 2004

The way that web services are currently being developed places them beside rather than within the existing World Wide Web. In this paper, we present an approach that combines the strength of the World Wide Web, viz. interlinked HTML pages for presentation and human consumption, with the strength of semantic web services, viz. support for semi-automatic composition and invocation of web services that have semantically heterogeneous descriptions. The objective we aim at eventually is that a human user e.g. a consultant or an administrator can seamlessly browse the existing World Wide Web and the emerging web services and that he can easily compose and invoke Web services on the fly.This paper presents our framework, OntoMat-Service, which trades off between having a reasonably easy to use interface for web services and the complexity of web service workflows. It is not our objective that everybody can produce arbitrarily complex workflows of web services with our tool, the OntoMat-Service-Browser. However, OntoMat-Service aims at a service web, where simple service flows are easily possible—even for the persons with not much technical background, while still allowing for difficult flows for the expert engineer.

Service discovery and service composition are two crucial issues in the emerging area of Service-oriented Computing (SoC). The introduction of semantic an-notations in Web service descriptions can support the discovery process of services and guide their composition into workflows. In this paper, we propose a Structured Rela-tionship Algebra that extends existing frameworks for semantic service descriptions by a set of algebraic operators and allows to define in a uniform way formal semantic annotations regardless the framework adopted to describe service semantics. The pro-posed algebra is comprised by a set of three algebraic operators and allows to define new objet properties at the ontology level called derived properties. Derived properties are used to describe the data transformation processed by a service by associating con-straints on both properties and instances of the concepts and their related ontological relationships.

A Knowledge based Approach for Semantic Web Services Discovery, 2016

Ever since the introduction of the service oriented model of computing (SOA), service discovery has been the major research challenge in SOA. Service consumers usually prefer to express their requirements informally. Expressing requirements in such a way leads to difficulties in the matching procedure, and hence results in poor matching results. In this paper, we present the concept of multi-level search as a solution for matching informal expression of user requirements. In the suggested approach, intermediate brokers receive service requests and suggest suitable services that match the given requests. We present a mechanism by which an intelligent broker utilizes a knowledge based system to overcome the drawbacks of syntactic and semantic discovery. The intelligent broker receives informal user requirements and performs multi-level search. The search starts with key word search, then meaning search, and finally expert search. If the keyword search fails to produce a proper matching, then, the search progresses to the following levels: semantic, and then intelligent search. In this paper we argue that multi-level search could revive the dream of automatic service discovery and present a detailed model for implementation.

Web services are already one of the most important resources on the Internet. As an integrated solution for realizing the vision of the Next Generation Web, semantic web services combine semantic web technology with web service technology, envisioning automated life cycle management of web services. This paper discusses the significance and importance of service discovery & selection to business logic, and the requisite current research in the various phases of the semantic web service lifecycle like discovery and selection. We also present several different composition strategies, based on current research, and provide an outlook towards critical future work.

2004

The next Web generation promises to deliver Semantic Web Services (SWS); services that are self-described and amenable to automated discovery, composition and invocation. A prerequisite to this, however, is the emergence and evolution of the Semantic Web, which provides the infrastructure for the semantic interoperability of Web Services. Web Services will be augmented with rich formal descriptions of their capabilities, such that they can be utilized by applications or other services without human assistance or highly con-strained agreements on interfaces or protocols. Thus, Semantic Web Services have the potential to change the way knowledge and business services are consumed and provided on the Web. In this paper, we survey the state of the art of current enabling technologies for Semantic Web Services. In addition, we characterize the infrastructure of Semantic Web Services along three orthogonal dimensions: activities, architecture and service ontology. Further, we examine and contrast three current approaches to SWS according to the proposed dimensions.

PhD Dissertation, 2013

As the utilization and development of Web services grows rapidly, the problem of analysing of existent Web services naturally arises. The analysis provided by the recent research work mostly extends to the statistical and explanatory examination of collections of Web services while deeper analysis of semantically annotated versions of services and the practical usage of the results of analysis are yet to receive substantial attention. The vast major- ity of existing web services lack any kind of formally expressed semantics, making semantic annotation a crucial preliminary step for analysis. In the absence of appropriate reference domain ontologies, annotation of existing web services is dependent on ontology development and ontology learning techniques. There is a great need for the development of automated ontology learning systems that allow semantic annotation of large collections of web services lacking any auxiliary textual materials. There is also a lack of effec- tive evaluation frameworks for assessing the quality of the provided semantic annotation on a large scale. The availability of a large quantity of semanti- cally annotated web services should allow the development of service selection and composition methods, taking advantage of domain diversity and the real- world characteristics of Web services. Moreover, user-generated contents such as tags and ratings in social networks are a rich source of information that can be exercised to perform more efficient service selection. Similarly, any method that targets the employment of user profiles in a social network needs to address a plausible solution for privacy issues. The main contribution of this dissertation is the development of techniques and frameworks supporting the construction, exploitation, and analysis of semantic web services. Specifically, we developed a semi-supervised method for ontology learning from Web service interface descriptions (WSDLs). The generated ontology is later used for semantic annotation of the examined web services. We also introduced a problem ontology as a specific case of task ontology, decomposing the given user query into a set of web services satisfying user requirements. The feasibility of problem ontology is evaluated as an action-planning component for a multi-robot system. Further, we developed an evaluation approach, suitable for the effective evaluation of large-scale, heterogeneous, real-world web service annotations. The approach consists of a set of procedures and metrics from network theory applied to the network structure of web services. The network is constructed by linking web services via matching input and output parameters of their operations. These web service networks are used to discover information exchange patterns among communities of services. The determined patterns can be employed for more effective service selection and composition strategies. Finally, in the context of a social network, we introduce a framework for privacy trust-aware user profile utilization. The efficiency of this framework is evaluated in the context of a user item-based recommendation system

Electronic Workshops in Computing, 2010

Web services have become a new industrial standard offering interoperatability among various platforms but the discovery mechanism is limited to syntactic discovery only. The framework named ADWebS is proposed in this paper for automatic discovery of semantic Web Services, which can be considered as an extension to one of the most prevalent frameworks for semantic Web service, WSDL-S. At the first stage, the framework proposes manual semantic annotations of Web service to provide the functional description of the services in Web Service Description Language(WSDL)'s < document > tag. These annotations are extracted and term-category matrix is formed, where category denotes a class in which a Web service will be added. Next, Semantic relatedness between terms and pre-defined categories is calculated using Normalized Similarity Score (NSS). A nonparametric test, Kruskal Wallis test, is applied on values generated and based on the test results, services are put into one or more pre-defined categories. The user or the requestor of the service is directed to the semantically categorized Universal Description Discovery and Integration (UDDI) repository for discovery of required service. Experimental results on a dataset covering multiple Web services of various categories show a significant improvement over the current state-of-the-art Web service discovery methods.

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Advances in Grid …, 2005

Interactive applications like Problem Solving Environments require on demand access to Web Services, where the services are autonomously discovered, composed, selected and invocated based on a description of requested capabilities. Semantic Web Services aim at providing semantically interpretable capabilities through the use of shared ontologies. We demonstrate how Grid Services for an interactive biomedical application are annotated with a domain ontology, and propose algorithms for automated composition and selection of workflows, where workflows are created by semantically matching service capabilities, and where workflow selection is based on a trade-off between the types of semantic matches in the workflow and the number of services. The algorithms are demonstrated on semantically annotated Grid Services in the biomedical application.

2011

Semantic Web services evolved from traditional computational services by semantic descriptions. Recently, there have been many research efforts in the •eld of semantic Web services, which reveals enormous potential for Service-Oriented Architecture to be promoted to an improved architecture. However, world-altering services have been largely disregarded because of the limited facilities in current description languages to express required conditions. Enterprise Application Integration systems need world-altering services because most of the business services need preconditions to be held prior to their service execution. Moreover, they generate effects, both of which must be contemplated in the service environment. To exploit the semantic Web services in reality, ef•cient discovery and composition approaches need to be developed to complement the service environment requirements. This paper intends to overview selective methods for discovery and composition of worldaltering semantic Web services.