Ontology-Based Query Interface in a System for Semantic Integration of XML Data

We present an ontology-oriented approach to formulate queries in XML data integrating system in P2P environment. In this approach, XML schema trees (tree-pattern schemas) are annotated in a global domain ontology by terms of some OWL categories. The annotations are then used to two purposes: (1) to infer mappings between local XML schemas, and (2) to create local "ontology views'; which can be queried by users. We propose a set of rules for inferring mappings between XML schemas based on semantic relationships between terms used for annotating these schemas. Queries are issued against the local ontology using a user-friendly GUI. The query is answered in the local data source as well as in semantically connected data sources in a distributed P2P connected system. In this way the following objectives are accomplished: (1) queries can be formulated in a natural way conforming to the user's understanding of the application domain, (2) queries are executed in a dynamic P2P system, where answers are obtained from many data sources semantically connected by means of mappings between their schemas; (3) queries are efficiently executed by translating them into XQuery programs.