AMetaCar - a Mediated eCommerce-Solution for the Used-Car-Market

Providing integrated access to multiple information offerings on the Web poses some fundamentally new challenges for practical federated information systems. Other than conventional databases with an explicit and rather stable schema and expressive query APIs, Web-sources deliver semi-structured data without explicit logical structure and semantics, and have rather limited query capabilities. In this paper we present AMetaCar, a federated Web-information system, that provides integrated access to a number of existing Web-catalogues for used cars. At the wrapper level, the sources are continually monitored, and their implicit structure is explicated by means of XML. At the mediator level a hybrid approach is used, which combines a relational DBMS for the regular and common attributes of used-car offers with a persistent XML-DOM (Document Object Model) implementation for the irregular and heterogeneous attributes. XSL is used for presenting XML results. This overall approach combines ..