The authors propose a query mediation framework to support customizable information gathering across heterogeneous and autonomous information sources. Instead of an integrated (and static) global schema, they propose an adaptive approach to interoperability which allows information consumers to represent their queries based on the customized personal view rather than at system-defined integrated view. The query mediation framework consists of five steps: query routing, query decomposition, parallel access plan generation, subquery translation and execution, and query result assembly. Concrete examples illustrate the challenges arising from heterogeneity in these five steps and how the framework scales up as the number of information sources grow and evolve.
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