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Metadata Registries and Interoperability

Hugo Manguinhas(hugo.manguinhas@ist.utl.pt)
INESC-ID - Information Systems Group

A purpose of our work is to contribute to the development of solutions for interoperability based on Metadata Registries (MDR). The problem to address occurs when one information system, in the scope of a specific business process, receives from another system an information object coded according to a schema of which it is not aware. We consider the hypothesis that in those scenarios it might be possible to translate that object to a schema recognized by the receiver if the two schemas and the corresponding mapping information are properly registered in MDRs and can be accessed for that purpose.

The ISO11179 MDR specification “addresses the semantics of data, the representation of data, and the registration of the descriptions of that data”. The standard is focused on generic representation of information and thus provides a meta-model which is, at the representational level, independent of any specific information meta-schema (XML Schema, database schema, etc.) and, at the concept level, independent of any specific knowledge representation paradigm (e.g. semantic network, description logics, etc.). The ISO11179 specification also enables the representation of mapping information through relationships between the representational and the conceptual levels, which represents a form of intermediate mapping between different representational domains.

However, defining the information schema and the corresponding mapping information is only part of the solution. In order to achieve interoperability one must perform cross-walks between schemas, which should be achieved at a level upper to the MDRs. In this sense, in a scenario where an engine is required to “translate” one specific document in a specific schema into a corresponding copy in another schema, that mapping engine must be able to identify the information schemas, locate the corresponding MDRs, reason over the available mappings and perform the translation.

In order to do this it is required that the information schemas and the conceptual domain are bounded respectively to a given meta-schema and knowledge representation formalism. The required meta-model must be flexible enough for representing: (1) all the constructs and constraints defined in a given information schema; (2) all the logic statements defined in a knowledge representation language; and (3) all the mapping information required to perform the cross-walk, preferably using a proper mapping language. From the analysis of these requirements, we have identified some limitations in the ability of the ISO11179 meta-model to represent the required information, whether at the representational level or at the conceptual level or even relative to the mapping information.

This presentation will discuss some possible changes to the ISO11179 meta-model specification in order to better support these requirements, as also a proposal for guidelines for the encoding of information in order to facilitate machine schema translation. We will also propose another approach for the meta-model based on the RDF specification.

Finally, we will present a structure for a possible project for the development of a mapping service using the information provided by MDRs (especially ISO11179 compliant MDRs).

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