On Semantic-based cooperation among Web Services

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.

The semantic organization and description of Web services is an important requirement for enabling the automatic composition of Web services. The number of Web services available on the Web is large and continuously changing. Additionally, service providers may be located in different places over the world. Finally, the large scale, dynamics, and heterogeneity of Web services may hinder any attempt for “understanding” their semantics and hence out- sourcing them. This calls for techniques to organize Web services in a way they can be efficiently “understood” and outsourced.

Through providing an execution environment for semantic web services, SWSF (Semantic Web Service Framework) can facilitate automatic web service delivery, discovery, selection, invoking, composition and interoperation. However, each of those ongoing approaches does not satisfy all basic requirements of SWSF, e.g. OWL-S (Ontology Language of Web Service) does not offer the mechanism for automatic web service tasks' execution and WSMO can not describe the composition of web services in a structural way yet. So, in order to provide a fully- fledged SWSF, we present the ISCF (Integrated Service Composition Framework) which is based on the OAA (Open Agent Architecture ). We describe the technical characters and design objectives of ISCF from global and detailed view. Comparing with other SWSFs, ISCF has more extensible and autonomous distributed architecture, and has more complete and effective web service automatization. In addition, ISCF provide some useful tools to help users design semantic web services and manage ISCF system.

This paper presents a new approach for automatic Web service composition based on the formalism of Fluent Calculus using semantic Web service descriptions. In our approach, the Web service composition process is viewed as an AI planning problem in the Fluent Calculus formalism. To semantically describe Web services, we have used a Web service domain ontology which is then translated into a Fluent Calculus knowledge base, necessary for the composition planning phase. For verifying the composed services, the Label Transition System Analyzer (LTSA) formalism is used. The paper also presents an experimental prototype for the Fluent Calculus based Web service composition and demonstrates its effectiveness with the help of an application scenario from the social event planning domain.

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.

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.

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.

The increasing popularity of Web services for application integration has strengthened the need for automated Web service composition and joint execution. A lot of attention has been paid recently towards techniques for creating a composite Web service from individual Web services based on user requirements, and driven by a variety of criteria. However, the major lacuna so far in Web service composition is the lack of a holistic requirements-driven approach for modeling the Web service execution lifecycle. In this paper we present such an approach based on our earlier work on context-driven Web service modeling. In particular, we separate requirements into two parts - functional and extrafunctional requirements (FRs and EFRs, respectively). We express FRs as commitments made by individual Web ser-vices towards the composite Web service, and EFRs as rules that constrain the behavior of the individual Web services while they execute against their FRs. We also present a conceptual model that can be used for tracking requirements during Web service execution.

The automatic composition of Web services requires the existing services to be encoded in a semantic form, such as ontology. If Web services are represented with ontology, we can automatic compose Web services by means of their semantics. Ontology modeling is divided into two steps: input/output parameters modeling and Web services modeling. First, we collect Web services' input/output parameters, represent them with classes in ontology, and transform Web services to properties in ontology, define relations between classes and properties. Then we judge Web services' relations based on relations between properties transformed from these Web services and estimate whether these Web services can be composed.

Web services provide a promising solution to an age old need of fast and flexible information sharing among people and businesses. One of the key research issues in web services is selection of most pertinent web services. Selection of web service has become a tedious job because of the increasing number of service providers providing services with similar functionality. Therefore, a framework for selection and discovery of web service that can meet the non-functional requirements is needed. In this work, we have developed a selection tool (WSS-NFP) for web services which can rank services based on their non functional properties such as performance, delay etc. We have used soft computing techniques for selection and discovery of web services based on non functional properties. These properties are fuzzy in nature. A tool is developed and implemented that is generic in nature and can be customized for any application domain. As a core of this tool, it consists of Fuzzy System for ranking web services and Neural Network for fine tuning the membership functions for linguistic terms. Appropriate and fine tuned membership functions help in minimizing the output error measure and maximizing the performance index of the proposed tool. This tool is basically a Neuro-Fuzzy system for ranking web services of any domain.

Management applications of the Web Service Offerings Language (WSOL)

The potential benefits of Web services composition heavily rely on semantic interoperability, i.e., the ability to exchange data meaningfully amongst Web services. Context heterogeneity, which refers to different implicit assumptions about interpreting the exchanged data, hampers the automatic composition of Web services. However, existing initiatives of Semantic Web Services (SWSs) often ignore context heterogeneity. In this paper, we introduce an approach to address this issue. The contexts of the involved Web services are defined in a lightweight ontology and their WSDL descriptions are annotated by an extension of a W3C standard, i.e., Semantic Annotation for WSDL and XML Schema (SAWSDL). The composition of Web services is described using BPEL specification. Given a BPEL file that ignores context heterogeneity, the approach automatically detects all context differences among the involved services, and reconciles them by producing a mediated BPEL file that incorporates necessary conversions using XPath functions and/or 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.

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.

We apply our work on Web service discovery with initially incomplete information to the problem of service composition. Rich semantic descriptions of Goals and Web services allow the unambiguous specification of constraints on what services are required and offered respectively. However, the data provided in service descriptions may be incomplete. We describe how missing instance data may be fetched dynamically and used for richer service discovery. We show how the resultant knowledge base can be used for simple compositions of services having mutual constraints.