A Web Query System for Heterogeneous Government Data

Abstract

This paper describes a Web-based query system for semantically heterogeneous government-produced data. Geospatial Web-based information systems and portals currently are being developed by various levels of government along with the GIS community. Typically, these sites provide data discovery and download capabilities but do not include the ability to pose DBMS-type queries. One of the main problems in querying distributed government data sources is the difference in semantics used by various jurisdictions. We extend work in schema integration by focusing on resolving semantics at the value level in addition to the schema or attribute level. We illustrate our method using land use data, but the method can be used to query across other heterogeneous sets of values. Our work starts from an XML Web-based DBMS and adds functionality to accommodate heterogeneous data between jurisdictions. Our ontology and query rewrite systems use mappings to enable querying across distributed heterogeneous data.