multi-dimensional service-oriented ontology mapping

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  • Nuno Alexandre Pinto da Silva

    MULTI-DIMENSIONAL SERVICE-ORIENTED

    ONTOLOGY MAPPING

    Universidade de Trs-os-Montes e Alto Douro Vila Real, 2004

  • Multi-Dimensional Service-Oriented

    Ontology Mapping

    a thesis submitted for the Degree of Doctor of Philosophy by

    Nuno Alexandre Pinto da Silva

    supervised by

    Professor Joo Manuel Simes Rocha

    Professor Jos Carlos Silva Cardoso

    Universidade de Trs-os-Montes e Alto Douro

    Vila Real, Portugal

    September 2004

  • iii

    ABSTRACT

    Ontology mapping is the process whereby semantic relations are defined between two ontologies at

    the conceptual level, which in turn are applied at data level transforming source ontology instances

    into target ontology instances. Ontology mapping, as an information integration approach, faces

    new challenges with the advent of new technological and socio-organizational paradigms such as

    Semantic Web and Virtual Organizations, especially due to the unprecedented levels of distribution,

    heterogeneity and evolution.

    The first contribution of this thesis is MAFRA MApping FRAmework, a systematized

    interpretation of the ontology mapping process. MAFRA identifies, integrates and organizes the

    ontology mapping process phases and complemented modules into a meaningful reference model.

    Due to its wide coverage it further provides a classification artifact for works from distinct but

    interrelated research fields. While MAFRA identifies several other phases of the process, the rest of

    the research developed in the scope of this thesis specially focuses on the core phases of the

    process: the specification and execution of semantic relations.

    The Semantic Bridging Ontology (SBO) is the result of the research on analysis, characterization,

    specification and representation of semantic relations. SBO describes the semantic relations domain

    of knowledge, providing not only a reasoning mechanism but also a representation and exchange

    mechanism of semantic relationships, when instantiated. SBO is a very simple and compact

    ontology, but its extensional structure based on transformation services allows its adoption in very

  • Abstract

    iv

    distinct and complex scenarios. While most of the syntactical relations are provided by

    transformation services, the structural relations are provided by the entities and their relationships

    defined by SBO. Furthermore, because SBO clearly and univocally characterizes the different types

    of semantic relations and their behaviors, it serves as a driving mechanism for the specification of

    semantic relations. SBO is further complemented by a software application with a graphical user

    interface that allows the definition and the automatic storage and verification of the semantic

    relationships.

    The semantic relationships resulting from previous phase are then applied in the execution phase.

    The general-purpose transformation process proposed in this thesis conforms to and exploits the

    SBO conceptualization, namely concerning the notion of transformation service. The proposed

    transformation process distinguishes between the generic query and filtering of instances, and the

    specific transformation provided by the transformation services associated with each semantic

    relation. The query and filtering phases of the process require specific and extensive processing of

    data according to the semantic relationships specification, which have been specified recurring to

    the formal, well-known relational data model algebra, motivating a formal yet very explicit and

    especially very compact description of the process. Adopting the query-filtering-transformation

    method, the process exploits and promotes the notion of independent transformation service,

    allowing the inclusion and modification of the transformation capabilities of the system with no

    modification of other components of the system.

    This independent transformation service approach is extrapolated into the notion of multi-

    dimensional service in which services capabilities are no longer limited to the transformation of

    instances but to other phases of the process, namely the semantic relation specification, verification,

    evolution and negotiation. This new notion of service is further integrated in the multi-dimensional

    service-oriented architecture, in which services represent and embody specific expertise on the

    application of the service itself along the semantic relationships life-cycle, providing competencies

    as requested to the core phases of the process.

    The potential advantages of the multi-dimensional service-oriented architecture are tested and

    exploited in the researched process for automatic definition of semantic relationships. In this case

    test, services are expanded with competencies to judge the relevance of a set of similarities

    measures in the definition and confirmation of a semantic relation with which the service is

    associated.

    The proposed ideas and processes have been implemented in the scope of this thesis into the

    MAFRA Toolkit application, and tested with several ontology mapping scenarios. Additionally, The

    MAFRA Toolkit has been applied and tested in the scope of several third-party EU-funded

    projects.

  • v

    RESUMO ALARGADO

    Sendo ontologia uma descrio das caractersticas do contedo de repositrios de dados,

    informao ou conhecimento, torna-se possvel atravs da definio de equivalncias semnticas

    entre os elementos das ontologias, relacionar esses repositrios. Mapeamento de ontologias um

    processo que consiste na definio a nvel ontolgico dessas relaes semnticas entre entidades de

    uma ontologia de origem e de uma ontologia de destino. Essas relaes so posteriormente

    aplicadas na transformao das instncias duma base de conhecimento conforme com a ontologia

    de origem em instncias duma base de conhecimento conforme com a ontologia de destino.

    O trabalho realizado nesta tese genericamente dividido em sete partes, que correspondem ao

    longo da tese a outros tantos captulos:

    1. Motivaes;

    2. Ontologia;

    3. MAFRA MApping FRAmework;

    4. Relacionamento semntico;

    5. Execuo das relaes semnticas;

    6. Arquitectura do sistema baseada em servios multi-dimensionais;

    7. Desenvolvimento e experincias.

    As seces seguintes descrevem sumariamente o trabalho desenvolvido e os resultados mais

    relevantes atingidos em cada uma delas, sendo a ltima seco reservada apresentao duma

  • Resumo Alargado

    vi

    sntese do trabalho desenvolvido e apresentao de alguns indicadores da relevncia e utilidade da

    investigao realizada.

    1. Motivaes

    Mapeamento de ontologias considerada uma tecnologia fundamental em cenrios em que a troca

    e partilha de informao sejam essenciais. Interoperabilidade entre sistemas de informao, web

    semntica, organizaes virtuais e negcios electrnicos, migrao de dados entre sistemas e

    evoluo dos modelos de dados subjacentes aos sistemas de informao, so alguns desses cenrios.

    Atravs da anlise e sistematizao das caractersticas e das necessidades de interoperabilidade

    associados a estes cenrios, definiram-se os seguintes requisitos dum sistema de mapeamento de

    ontologias:

    1. Identificao, especificao e representao de relaes sintcticas, estruturais e semnticas entre

    ontologias;

    2. Transformao da informao transmitida entre intervenientes na comunicao, de acordo com

    as relaes anteriores;

    3. Negociao das relaes anteriores;

    4. Manuteno das relaes anteriores;

    5. Integrao (mas minimizao) da participao do ser humano no processo de mapeamento de

    ontologias, o que sugere a adopo dum sistema semi-automtico de mapeamento de ontologias;

    6. Adopo de tecnologia e solues do contexto da web semntica.

    Estes requisitos sero posteriormente comparados com a investigao realizada e com os resultados

    atingidos, o que permite aferir da qualidade da investigao e dos resultados atingidos.

    2. Ontologia

    No existe uma definio universalmente aceite de ontologia, mas a definio de Gruber -

    ontologia uma especificao explcita duma conceptualizao tende a ser genericamente aceite

    no contexto dos sistemas de informao e conhecimento. No contexto desta tese porm, esta

    definio demasiado genrica, o que motiva a anlise de caractersticas e comparao com outros

    conceitos comumente relacionados, nomeadamente com o conceito de esquema de base de dados.

    Da comparao efectuada conclui-se que ambos partilham vrios pressupostos e caractersticas,

    mas torna-se contudo evidente que, mesmo no sendo conceptualmente e formalmente universais,

    as capacidades de descrio e caracterizao semntica do domnio de conhecimento de ontologia

    so superiores s do esquema de base de dados. Partindo desta observao conclui-se que ontologia

    , de ambos, o artefacto potencialmente mais capaz de fornecer elementos de raciocnio para a

    definio de relaes semnticas entre repositrios de dados, informao e/ou conhecimento.

  • Multi-Dimensional Service-Oriented Ontology Mapping

    vii

    Concluindo o tema sobre a caracterizao do conceito de ontologias, introduz-se uma especificao

    formal do modelo de ontologia que ser usada no decorrer da tese. Os elementos bsicos de

    ontologia so:

    Conceito, que corresponde noo de classe na modelao o

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