Michael Stollberg

Web Service Modeling Ontology

The potential to achieve dynamic, scalable and cost-effective marketplaces and eCommerce solutions has driven recent research efforts towards so-called Semantic Web Services that are enriching Web services with machine-processable semantics. To this end, the Web Service Modeling Ontology (WSMO) provides the conceptual underpinning and a formal language for semantically describing all relevant aspects of Web services in order to facilitate the automatization of discovering, combining and invoking electronic services over the Web. In this paper we describe the overall structure of WSMO by its four main elements: ontologies, which provide the terminology used by other WSMO elements, Web services, which provide access to services that, in turn, provide some value in some domain, goals that represent user desires, and mediators, which deal with interoperability problems between different WSMO elements. Along with introducing the main elements of WSMO, we provide a logical language for defining formal statements in WSMO together with some motivating examples from practical use cases which shall demonstrate the benefits of Semantic Web Services.

Semantic web portals: state‐of‐the‐art survey

Purpose – To present the state of the arts application of semantic web technologies in web portals and corresponding achievable improvements for identifying the potential improvement made by semantic web technology.Design/methodology/approach – An evaluation scheme is proposed to investigate various web portals that make use of semantic web technologies in order to identify their strengths and weaknesses. This scheme consists of three layers: information access, information processing and grounding technologies. Two academic portals and two commercial portals are selected based on the definition of semantic web portal. Detailed evaluation based on the proposed scheme is conducted on these four select portals.Findings – Semantic web technologies can definitely increase the information consistency and the information processing quality of web portals by using ontologies to model portal structure and consensus knowledge. Furthermore, semantic web services will be acting as the key technologies to lift curren...

A caching mechanism for semantic web service discovery

The discovery of suitable Web services for a given task is one of the central operations in Service-oriented Architectures (SOA), and research on Semantic Web services (SWS) aims at automating this step. For the large amount of available Web services that can be expected in real-world settings, the computational costs of automated discovery based on semantic matchmaking become important. To make a discovery engine a reliable software component, we must thus aim at minimizing both the mean and the variance of the duration of the discovery task. For this, we present an extension for discovery engines in SWS environments that exploits structural knowledge and previous discovery results for reducing the search space of consequent discovery operations. Our prototype implementation shows significant improvements when applied to the Stanford SWS Challenge scenario and dataset.

Two-Phase Web Service Discovery Based on Rich Functional Descriptions

Discovery is a central reasoning task in service-oriented architectures, concerned with detecting Web services that are usable for solving a given request. This paper presents two extensions in continuation of previous works towards goal-based Web service discovery with sophisticated semantic matchmaking. At first, we distinguish goal templates as generic objective descriptions and goal instances that denote concrete requests as an instantiation of a goal template. Secondly, we formally describe requested and provided functionalities on the level of state transitions that denote executions of Web services, respectively solutions for goals. Upon this, we specify a two-phase discovery procedure along with semantic matchmaking techniques that allow to accurately determine the usability of a Web service. The techniques are defined in the Abstract State Space model that supports several languages for describing Web services.

On the semantics of functional descriptions of web services

Functional descriptions are a central pillar of Semantic Web services. Disregarding details on how to invoke and consume the service, they shall provide a black box description for determining the usability of a Web service for some request or usage scenario with respect to the provided functionality. The creation of sophisticated semantic matchmaking techniques as well as exposition of their correctness requires clear and unambiguous semantics of functional descriptions. As existing description frameworks like OWL-S and WSMO lack in this respect, this paper presents so-called Abstract State Spaces as a rich and language independent model of Web services and the world they act in. This allows giving a precise mathematical definition of the concept of Web Service and the semantics of functional descriptions. Finally, we demonstrate the benefit of applying such a model by means of a concrete use case: the semantic analysis of functional descriptions which allows to detect certain (un)desired semantic properties of functional descriptions. As a side effect, semantic analysis based on our formal model allows us to gain a formal understanding and insight in matching of functional descriptions during Web service discovery.

A Refined Goal Model for Semantic Web Services

The idea of service orientation envisions dynamic detection and execution of suitable Web services for solving a particular request. Most realization approaches pay only little attention to the client side of such architectures. We therefore promote a goal-driven approach: a client merely specifies the objective to be achieved in terms of a goal, and the system resolves this by automated detection, composition, and execution of Web services. Extending the WSMO framework, we present a model for describing goals as formalized client objectives that carry all information relevant for automated detection and execution of Web services.

A Semantic Web Mediation Architecture

Heterogeneity is an inherent characteristic of open and distributed environments like the Internet that can hamper Web resources and Web services from successful interoperation. Mediation can be used to resolve these issues, which are critical problems in the Semantic Web. Appropriate technologies for mediation need to cover two aspects: first, techniques for handling the different kinds of heterogeneity that can occur between Web resources, and secondly logical components that connect resources and apply required mediation technique along with invocation and execution facilities. This paper presents an integrated model for mediation on the Semantic Web with special attention to Semantic Web services that is developed around the Web Service Modeling Ontology WSMO. Covering both dimensions, we explain the techniques developed for handling different types of heterogeneity as well as the components and architecture for establishing interoperability on the Semantic Web if not given a priori.

h-TechSight — A Next Generation Knowledge Management Platform

A new breed of Knowledge Management Systems (KMS), referred to as the Next Generation of Knowledge Management (NGKM), aims at overcoming the limitations of existing KMS regarding the range and quality of supportable Knowledge Management activities. Therefore, AI-based technologies are employed to enable automated knowledge item processing instead of the information retrieval functionality provided by conventional KMS. This paper presents the Knowledge Management Platform (KMP) developed in the h-TechSight project as an NGKM solution. It is designed to support organizations in technology intensive industries in monitoring changes in their external environment as an important factor in competitiveness. Therefore, the KMP combines NGKM enabling technologies for automatically observation of information resources on the Internet in order to notify users whenever a change in their domain of interest occurs. The aim of this paper is to position the KMP as a KMS of the next generation and to delineate the lessons learned in KMS design in the h-TechSight project. Thus, we illustrate the idea of NGKM with special emphasis on enabling technologies and, on this basis, expose the functional design and technical realization of the h-TechSight KMP.

Semantic Web Fred - Automated Goal Resolution on the Semantic Web

Semantic Web Fred, SWF for short, is a context-independent, goal-driven system for automated execution of tasks that are delegated to electronic representatives along with dynamic service usage. A task is assigned to an agent for automated resolution, represented as a Goal. This is used to determine potential partners for collaborative task resolution, and for discovery of suitable goal-resolving services that can be internal implementations as well as external Semantic Web Services. The SWF technology integrates agent technology, ontologies, and Semantic Web Service technologies - the technological building blocks identified for the Semantic Web - into a coherent system. This paper describes the architecture of SWF, explains the mechanisms for establishing automated and cooperative goal resolution, and the alignment of SWF with the Web Service Modeling Ontology WSMO, a well-structured overall framework for Semantic Web Services. We also outline the contribution of SWF to the development of Semantic Web technologies.

Semantic Web services tutorial

Summary form only given. The emerging concept of semantic Web services aims at more sophisticated Web Service technologies: on basis of semantic description frameworks, intelligent mechanisms are envisioned for discovery, composition, and contracting of Web services. The tutorial explains the current state of the art in semantic Web services on basis of the Web service modeling ontology WSMO and related initiatives. Commencing from the vision and arising challenges for semantic Web services, the tutorial in detail explains the specifications of recent frameworks for semantic Web services and presents the Web service execution environment WSMX as the WSMO reference implementation. The tutorial consists of three main sections that subsequently provide a complete overview of semantic Web services and the latest status of WSMO. The tutorial addresses academic as well as industrial researches and developers that are working with Web services and are interested in semantic Web services.