As database technology advances rapidly, there are usually heterogeneous databases used by different departments in an enterprise. On the other hand, the object oriented technology is becoming the dominant application development paradigm. Thus, there is a data modeling gap between applications and heterogeneous databases. We present some main architecture aspects of the system VHDBS which has been developed by an ongoing research project. This architecture provides a way to support cooperative access to distributed heterogeneous databases and to fill the data modeling gap in a distributed heterogeneous environment. Our work contributes not only to an implementation solution but also to an architecture framework and paradigmatic solution.