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Abstract : |
In such contexts as the Semantic Web, the components of an application increasingly rely on ontological models and content knowledge developed and maintained by independent contributors. These components also are designed to be building blocks of various applications. We advocate the use of a mediating component that defines and processes the knowledge transformations required to enable application components to exchange, and inter-operate on, knowledge and data. We present our approach and associated tools to support developers (1) in defining mapping relations between the ontologies involved in their application and (2) in running a mapping interpreter to mediate content knowledge and data among the corresponding ontology-based components. 1 Interoperation of Application Components As a multi-contributor environment, the World-Wide Web fosters the formation of applications that involve multiple, distributed components. In light of the Semantic-Web approach, ontologies?models that define the concepts, properties and relations of a domain of discourse?are the communication interface (if not the backbone) of these components meant to be assembled in various applications. Increasingly, however, such ontology-based application components are contributed independently and hence cannot be expected to adhere to shared models nor to integrate with one another gracefully. Instead, different components impose different semantic, structural and syntactic views and expectations on knowledge and data, expressed by means of independent ontologies. For example in a travel-planning application, a flight-booking component would conceive travel time as the exact day and time of a flight (e.g., ?Outbound on 05-01-2003 at 14h25min?), whereas a carreservation component might only need the approximate rental period (e.g., ?From Monday May 1st 2003 early evening to Sunday May 7th mid-morning plus or minus 1 day?). Such conceptual and representational mismatches need to be resolved at the ontological level in order to enable application components, |
