Schemas for Integration and Translation of Structured and Semi-structured Data

摘要

With the emergence of the Web as a universal data repository, research has recently focused on data integration and data translation, and a common data model of semistructured data has been established. It is being realized, however, that having a common schema model is also necessary, to support tasks such as query formulation, decomposition and optimization, or declarative specification of data translation. In this paper we elaborate on the theoretical foundations of a middleware schema model. We present expressive and flexible schema definition languages, and investigate properties such as expressive power and the complexity of decision problems that are significant in the context of data translation and integration.