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Web Services will transform the web from a collection of information into a distributed device of computation. In order to employ their full potential, appropriate description means for web services need to be developed. For this purpose we define a full-fledged Web Service Modeling Framework (WSMF) that provides the appropriate conceptual model for developing and describing web services and their...
Grids are an emerging computational infrastructure that enables resource sharing and coordinated problem solving across dynamic, distributed collaborations that have come to be known as virtual organizations. Unlike the web, which primarily focuses on the sharing of information, the Grid provides a range of fundamental mechanisms for sharing diverse types of resource, such as computers, storage, data,...
The development of the Semantic Web proceeds in layers. Currently the most advanced layer that has reached maturity is the ontology layer, in the from of the DAML+OIL language which corresponds to a rich description logic. The next step will be the the realization of logical rule systems on top of the ontology layer. Computationally simple nonmonotonic rule systems show promise to play an important...
This paper describes some initial work on a NetAPI for accessing and updating RDF data over the web. The NetAPI includes actions for conditional extraction or update of RDF data, actions for model upload and download and also the ability to enquire about the capabilities of a hosting server. An initial experimental system is described which partially implements these ideas within the Jena toolkit.
This paper describes a mini-experiment in using a tool for semantic annotation to index photographs of Windsor chairs, a type of antique furniture. The annotation tool makes use of an ontology based on art standards. We report on the experiences of subjects using the tool. The results suggest that a certain level of domain expertise is needed for semantic annotations, but also that an annotation tool...
For the Web to reach its full potential, it must evolve into a Semantic Web, providing a universally accessible platform that allows data to be shared and processed by automated tools as well as by people. The ‘Semantic Web’ is a recent initiative of the World Wide Web Consortium (W3C), with the goal of extending the current Web to facilitate Web automation, universally accessible content, and the...
It is useful to express the location of a node in a semantic graph in terms of a sequence of knowledge-bearing arcs that lead to the node from a node that is used as a point of reference. If the arcs on which such “graph-based addressing expressions” depend disappear, the expressions become invalid. When an arc is reified as a node, the reified arc may or may not be removed. If it is not removed,...
This paper suggests four steps towards the realization of a semantic web. Promotion of the idea should be based on practical application. There is need for the immediate development of practical demonstration applications. Simplicity and tolerance of error should be prime targets of research and development. An Open Source project to develop and populate a framework of tools and applications should...
The Resource Description Framework (RDF) describes graphs of statements about resources. RDF is a fundamental lower layer of the semantic web. This paper explores the equality of two RDF graphs in light of the graph isomorphism literature. We consider anonymous resources as unlabelled vertices in a graph, and show that the standard graph isomorphism algorithms, developed in the 1970’s, can be used...
The Resource Description Framework and the Resource Description Framework Schema Specification are supposed to be the foundations of the Semantic Web, in that all other Semantic Web languages are to be layered on top of them. It turns out that such a layering cannot be achieved in a straightforward way. This paper describes the problem with the straightforward layering and lays out several alternative...
The paper reviews the notions of expressiveness of description logics from (N. Kurtonina and M. de Rijke. Expressiveness of concept expressions in first-order description logics. Artificial Intelligence, 107:303–333, 1999) and exemplifies their use in the development in Semantic Web languages. The notion of bisimulation—which characterizes the description logic $$ \mathcal{A}\mathcal{L}\mathcal{C}...
Experience shows that the quality of the stored knowledge determines the success (therefore the effective usage) of an ontology. In fact, an ontology where relevant concepts are absent, or are not conformant to a domain view of a given community, will be scarcely used, or even disregarded. In this paper we present a method and a set of software tools aimed at supporting domain experts in populating...
RDF and RDF Schema are two W3C standards aimed at enriching the Web with machine-processable semantic data. We have developed Sesame, an architecture for efficient storage and expressive querying of large quantities of metadata in RDF and RDF Schema. Sesame’s design and implementation are independent from any specific storage device. Thus, Sesame can be deployed on top of a variety of storage...
Topic maps have been developed in order to represent the structures of relationships between subjects, independently of resources documenting them, and to allow standard representation and interoperability of such structures. The ISO 13250 XTM specification [2] have provided a robust syntactic XML representation allowing processing and interchange of topic maps. But topic maps have so far suffered...
The ability to rapidly locate useful on-line services (e.g. software applications, software components, process models, or service organizations), as opposed to simply useful documents, is becoming increasingly critical in many domains. Current service retrieval technology is, however, notoriously prone to low precision. This paper describes a novel service retrieval approached based on the sophisticated...
This paper describes two approaches for automatically converting RDF Schema and RuleML sources into an inference engine and storage repository. Rather than using traditional inference systems, our solution bases on mainstream technologies like Java and relational database systems. While this necessarily imposes some restrictions, the ease of integration into an existing IT landscape is a major advantage...
This paper deals with some modeling aspects that have to be addressed in the context of the integration of heterogeneous and autonomous XML resources. We propose an integration system, but the emphasis of this paper is neither on its algorithmic aspects nor on its technical details. Instead, we focus on the significance of offering appropriate high-level primitives and mechanisms for representing...
Describing web resources using formal knowledge (i.e., creating metadata according to a formal representation of a domain of discourse) is the essence of the next evolution step of the Web, termed the Semantic Web. The W3C’s RDF/S (Resource Description Framework/Schema Language) enables the creation and exchange of resource metadata as normal web data. In this paper, we investigate the use of RDFS...
The semantic discontinuity between World-Wide Web languages, e.g., XML, XML Schema, and XPath, and Semantic Web languages, e.g., RDF, RDFS, and DAML+OIL, forms a serious barrier for the stated goals of the Semantic Web. This discontinuity results from a difference in modeling foundations between XML and logics. We propose to eliminate that discontinuity by creating a common semantic foundation for...
This paper describes an approach to derive assessments about information sources based on individual feedback about the sources. We describe TRELLIS, a system that helps users annotate their analysis of alternative information sources that can be contradictory and incomplete. As the user makes a decision on which sources to dismiss and which to believe in making a final decision, TRELLIS captures...
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