Towards Constraint-Based Composition with Incomplete Service Descriptions

Directory services are a genuine constituent of any distributed architecture which facilitate binding attributes to names and then querying this information, that is, announcing and discovering resources. In such contexts, especially in a business environment, Quality of Service (QoS) and non-functional properties are usually the most important criteria to decide whether a specific resource will be used. To address this problem, we present an approach to the semantic description and discovery of web services which specifically takes into account their QoS properties. Our solution uses a robust trust and reputation model to provide an accurate picture of the actual QoS to user. The search engine is based on an algebraic discovery model and uses adaptive query-processing techniques to parallelise expensive operators. Architecturally, the engine can be run as a centralised service for small-scale environments or can be distributed among any number of cooperating registry providers.

Semantic Web Service technology provides a strong support for automation software development based on Web service. By analyzing the existing description models and methods of semantic Web service, a Semantic Web Service Description Model (WSDM4S) and its formal description based on SHOIN+(D) are proposed, which attempt to offer an effective model for description, publication, discovery, composition, and execution of Web services based on semantic description. And a Semantic Web Service Description Language (WSDL4S) based on XML is designed to support the WSDM4S. Based on WSDL4S, Web Services could be packaged into basic semantic unit of semantic software development.

A difficulty of sharing messages transferred among Web services is absence of common vocabulary, and the semantic organization and description of Web services is an important requirement for enabling the automatic discovery, selection, composition, execution and monitoring of Web services. This paper proposes a model for semantic-based interaction between Web services. The method defined some ontology-based vocabularies to describe different Web services and some mapping rules among those vocabularies. Compared with existing methods, the method considers the Web services together with the semantic interpretation, satisfiability and reasoning of distributed ontologies. So the method can ensure the share and reusage of term be used for describing parameters of Web services.

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 engine for automated discovery and composition on repositories of different sizes and present the results.

Ontologies as a means for semantic description of web services have been discussed for many years. Various formal languages and correspoding tools using ontologies for describing web services have also been proposed (i.e. OWL-S). However, these existing approaches mainly are targeting domain experts creating ontologies. They are often too complex to be used by an average service provider offering web services online. But for offering and retrieving web services from future electronic marketplaces or service registries, a semantic service description is necessary. Therefore, in this paper an approach for an easy-to-use web-based editor for describing web services using ontologies based on the OWL-S language is proposed and evaluated. It not only supports a semantic, but also a commercial description of the web service offered, while remaining compatible with previous approaches addressing such holistic web service descriptions.

Semantic Web Services are a search effort to automate the usage of Web services, a necessary component for the Semantic Web. Traditionally, Web service discovery depends on detail formal semantic descriptions of available services. Since a complete detailed service is not always feasible, the client software cannot select the best service offer for a given user goal only by using the static service descriptions. Dynamic discovery based on semantic description of services is an essential aspect of the Semantic Web Service integration process Some data needs to be obtained during run0time because not all data required for service discovery can always be included in service descriptions. This paper shows when and why complete semantic description is unfeasible and it defines the role and position of offer discovery. We propose an approach for offer discovery of semantic web services using OWL-S IDE during discovery process. We also present the algorithm, the implementation and some preliminary results.

Service-orientation for the development of complex distributed systems with reusable components (services) has proved to be highly beneficial approach in software engineering. In order to realize its advantages automated techniques and tools for finding services, selecting the ones that match requestor needs, composing them for achieving enhanced functionality and resolving heterogeneity issues are required. Adding semantics to web services has become the key approach for the automation of service-orientation environments. Current paper proposes semantic approach for service selection and integration. It considers the semantic description of web services and involves reasoning on a knowledge base. The proposed approach for web service discovery and integration is based on designing logic based techniques for matching goal description with the semantic annotation of web services. It provides for the automation of web service search which facilitates the design of practical applications in service-oriented environment.

Due to the lack of semantic descriptions of the Web services, the search results returned by the service registries are effectively inadequate. This paper presents the Semantic Web services Clustering (SWSC) method that extends the semantic representation of services and groups the similar Web services in order to improve the service discovery. The empirical analysis shows the improvement in service discovery with the use of SWSC.

Main challenges to the current semantic web service technologies are exponential continuous growth in the number of services on the Internet, syntax based discovery, lack of common agreed upon semantic service standards and heterogeneity of ontologies. In this paper, a service discovery approach independent of semantic service description models is proposed to solve the challenges of the current web service discovery. The idea is to combine principles from machine learning, data mining, statistical techniques and measures of semantic relatedness to make the semantic web service discovery process more intelligent, efficient and effective. The proposed approach exploits the use of semantic as well as syntactic information present within the service description profiles. Our approach is unique in terms of its application to any web service description language and the use of Omiotis measure of semantic relatedness for service discovery. The proposed approach has been implemented on OWL-S based service descriptions profiles and is able to find semantic relationship between the services which were otherwise discarded by the OWL-MX matchmaker. Empirical analysis shows that the proposed method out performs the

This paper presents PORSCE II, an integrated system that performs automatic Semantic Web service composition exploiting artificial intelligence (AI) techniques, specifically planning. Essential steps in achieving Web service composition include the translation of the Web service composition problem into a solver-ready planning domain and problem, followed by the acquisition of solutions, and the translation of the solutions back to Web service terms. The solutions to the problem, that is, the descriptions of the desired composite service, are obtained by means of external domain-independent planning systems, they are visualized and finally evaluated. Throughout the entire process, the system exploits semantic information extracted from the semantic descriptions of the available Web services and the corresponding ontologies, in order to perform composition under semantic awareness and relaxation.

Web services are the new paradigm for distributed computing. They offer interoperability of application and integration of large scale distributed systems. Amongst the web service standards, service registry is crucial to the overall utility of web service technology. However, the web services discovery mechanism pertaining with the UDDI [1] registry is inefficient because it only supports keyword-based and category-based matching, leading to irrelevant matches. Therefore, the provision of the scalable, flexible and robust web services publication and discovery system is crucial for the overall utility of web services. In this paper, we develop a scalable, robust and efficient infrastructure for web services publication and discovery amongst domain-based registries. More importantly, a novel algorithm is provided to classify web services into domain-based registries based on their semantic description. Experimental results show that our approach outperforms a centralized approach in terms of service discovery time.

This article tackles the problem of supplying the low level commanders with information from information sources located on higher command levels, distributed using web services, the most commonly used technology in modern command and control systems. There has been proposed the Adaptation Framework For Web Services Provision (AFRO) that defines a mechanism for effective web services invocation in tactical networks, which are considered disadvantaged in terms of available throughput, delay and error rate. Its implementation, in the form of AFRO Proxy performs so called adaptation actions, which are modifications of the SOAP XML messages by changing their encoding to more efficient or dropping information that are accepted to be removed by the service requester. The proposed adaptation mechanism gives promising effects for low level commanders located at the battlefield. They can be supplied with information generally available on high command levels, which, up to now, were very rarely distributed to tactical networks.

Semantic Web service matchmaking is the process of searching the space of possible matches between demands and supplies, and finds the best available ones. To achieve this, the semantic Web service matchmaking framework is one of the absolutely necessary components of service oriented architecture. This paper proposes a matchmaking framework based on Description Logic for semantic Web service described by RDF4S model, a novel semantic Web service description which consists of three layers: service oriented knowledge base, semantic description model and semantic description language. We describe the service description and service query conditions by using the ontologies that are included in service oriented knowledge base. The service resource specification is described according to Description Logics syntax and a Description Logic reasoner is used to compare service descriptions. By representing the semantics of service descriptions, the matchmaker enables the behavior of an intelligent agent to approach more closely that of a human user trying to locate suitable Web service resources.

Web services have emerged as a major technology for deploying automated interactions between distributed and heterogeneous applications. The main advantage of Web services composition is the possibility of creating value-added services by combining existing ones to achieve customized tasks. How to combine these services efficiently into an arrangement that is both functionally sound and architecturally realizable is a very challenging topic that has founded a significant research area within computer science. A great deal of recent Web-related research has concentrated on dynamic Web service composition. Most of proposed models for dynamic composition use semantic descriptions of Web services through the construction of domain ontology. In this paper, we present our approach to dynamically produce composite services. It is based on the use of two Artificial Intelligence (AI) techniques: Case-Based Reasoning (CBR) and AI planning. Our motivating scenario concerns a national system for the monitoring of childhood immunization.

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.