As in the DB Interface Module, the DB XA implementation of the RWDBConnection class is designed around the interface/implementation design pattern. In this pattern, a common interface hides the implementation differences of different database connections.

The DB XA version of each access module includes a new connection implementation class that derives from the corresponding connection implementation in the non-XA access module. For example, Oracle OCI has a new implementation class called RWDBOCIXAConnectionImp. This class derives from the non-XA implementation class RWDBOCIConnectionImp, and redefines the behavior of several methods.

Figure 3 illustrates the architecture of RWDBConnection classes.