Research of database access and integration in grid

A framework of database access and integration based on virtual logical database view is presented extending OGSA-DAI,The system is composed with MetaData Service(MDS) and Grid Virtual Database Service(GVDS).MDS searches the metadata catalog to find the physical databases that contain the required data.GVDS delegates global logical database and converts SQL query into search conditions to the physical databases,which uses a distributed query processing scheme to join multiple physical databases,realizing data access and queries transparently.