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Auflistung nach Autor:in "Embley, David W."

1 - 4 von 4
  • Konferenzbeitrag
    Combining the best of global-as-view and local-as-view for data integration
    (Information systems technology and its applications, 3rd international conference ISTA'2004, 2004) Xu, Li; Embley, David W.
    Currently, there are two main basic approaches to data integration: Globalas-View (GAV) and Local-as-View (LAV). However, both GAV and LAV have their limitations. In a GAV approach, changes in information sources or adding a new information source requires revisions of a global schema and mappings between the global schema and source schemas. In a LAV approach, automating query reformulation has exponential time complexity with respect to query and source schema definitions. To resolve these problems, we offer TIQS as an alternative point of view that is neither GAV nor LAV. The approach uses source-to-target mappings based on a predefined conceptual target schema, which is specified ontologically and independently of any of the sources. The proposed data integration system is easier to maintain than both GAV and LAV, and query reformulation reduces to rule unfolding. Compared with other data integration approaches, our approach combines the advantages of GAV and LAV, mitigates the disadvantages, and provides an alternative for flexible and scalable data integration.
  • Konferenzbeitrag
    A generalized framework for an ontology-based data-extraction system
    (Information systems technology and its applications, ISTA' 2005, 2005) Wessman, Alan; Liddle, Stephen W.; Embley, David W.
    Extraction of information from semi-structured or unstructured documents, such as web pages, is a useful yet complex task. Ontologies can achieve a high degree of accuracy in data extraction while maintaining resiliency in the face of document changes. Ontologies do not, however, diminish the complexity of a data-extraction system. As research in the field progresses, the need for a modular data-extraction system that decouples the associated processes continues to grow. In this paper we report on the implementation of such a system. The nature of our framework allows new algorithms and ideas to be incorporated into a data extraction system without requiring wholesale rewrites of a large part of the system's source code. It allows researchers to focus their attention on parts of the system relevant to their research without having to worry about introducing incompatibilities with the remaining components. We demonstrate the value of the framework by providing an implementation that exhibits appropriate characteristics.
  • Konferenzbeitrag
    An integrated ontology development environment for data extraction
    (2003) Liddle, Stephen W.; Hewett, Kimball A.; Embley, David W.
    Data extraction is a necessary technology to deal with the huge and growing collection of unstructured and semistructured information available on the World Wide Web. Ontology-based data extraction is a robust approach, but the construction of ontologies is a technical task requiring the services of a human expert. We present a Java-based tool for the graphical creation and testing of data extraction ontologies. This tool leverages standards such as Java and XML to provide a portable, extensible, maintainable, feature-rich environment. This tool reduces the burden on expert ontology developers and simplifies the task of ontology creation.
  • Konferenzbeitrag
    Representing generalization/specialization in XML schema
    (Enterprise modelling and information systems architectures, 2005) Al-Kamha, Reema; Embley, David W.; Liddle, Stephen W.
    XML is an effective universal data-interchange format, and XML Schema has become the preeminent mechanism for describing valid XML document structures. Generalization/specialization and its constraints are fundamental concepts in system modeling and design, but are difficult to express and enforce with XML Schema. This mismatch leads to unnecessary complexity and uncertainty in XML-based models. In this paper we describe how to translate various aspects of generalization/specialization from a conceptual model into XML Schema. We also explore what needs to be added to XML Schema to handle the other aspects of this fundamental modeling construct. If XML Schema were to include our proposed constructs, it would be fully capable of faithfully representing generalization/specialization, thus reducing the complexity of the XML models that rely on generalization/specialization.