Application of Universal Relation in the Data Access Middleware under Grid Environment

Qingyang Wang, Computer Network Information Center, Chinese Academy of Sciences, China

Data integration is one of the most important research areas in data grid. Distributed data resource and heterogeneous data schema bring difficulties to data integration. This article mainly focuses on how to deal with the heterogeneity of data schema in our data access system and put forward a blueprint to solve the heterogeneity problem of data schema. After three steps of meta-data transformation and regulation, the user's view of virtual database is a universal relation on which one poses queries. This query mode enables queries to merely refer to the basic universal relation rather than the underlying database. Further the local data resource based on universal relation is published through grid service. This blueprint provides a good platform to data integration in future. The last part of this article introduces the application of our DAS (Data Access System) in 45 research institutes of Chinese Academy of Sciences.

Keywords: Data Grid, universal relation, data integration, middleware, virtual database, scientific database.