| This thesis presents an ontology-based XML data integration framework that is capable of deriving an ontology from a collection of XML schemas in a semi-automatic manner and integrating heterogeneous XML sources at the semantic level. The ontology in our system is constructed following a layered approach where an intermediate model is introduced to explicate the underlying semantics of XML schemas and to reduce the complexity of ontology derivation. This two-phase approach is performed semi-automatically by applying a set of heuristic rules and by interpreting mapping information defined by users. The resulting ontology serves as a global semantic view over a set of data sources to be integrated. Moreover, we also adopt a data warehousing approach to populate this ontology with data from XML instance documents automatically, and support data cleaning functions over the resulting set of ontology instances. The proposed framework has been implemented and evaluated using off-the-web XML schemas. |
