Implementation Of Universal Data Access In DM DBMS

Universal Data Access is a set of interfaces presented by Microsoft Corporation to implement accessing relational and nonrelational datasources by a unified model. Universal Data Access consists of ADO and OLE DB interfaces.In order to make DM DBMS support Universal Data Access,we design and implement DM OLE DB Provider through ODBC provided by DM DBMS.DM OLE DB Provider can provide OLE DB interfaces for DM DBMS,which makes DM DBMS accord with Universal Data Access.First, on researchs of Universal Data Access,we point that the key point to implement Universal Data Access is to provide OLE DB interfaces and the key point to provide OLE DB interfaces is to implement OLE DB data provider.DM OLE DB Provder is OLE DB data provider for DM DBMS.Then,we choose ODBC from existing techniques of Data Access provided by DM DBMS to implement DM OLE DB Provider.COM is the key technique of implementation of the DM OLE DB Provider.In fact,OLE DB interfaces provided by DM OLE DB Provider are just the interfaces provided by inner COM objects.According to functions of DM DBMS,we design archtecture and all inner COM objects of DM OLE DB Provider and design OLE DB interfaces for all inner COM objects.And then,accord with COM criterion,we encapsulate functions of accessing DM databases by ODBC into inner COM objects of DM OLE DB Provider to implement OLE DB interfances of inner COM objects.Finally, in Visual C++ development environment,we use OLE DB template class provided by ATL to implement DM OLE DB provider and use conformance testing tools and sets in Microsoft Data Access SDK to test DM OLE DB Provider. Test results indicate that DM OLE DB Provider can provide OLE DB interfaces,whose functions are right,and gains the designing target.