When you generate a PowerBuilder COM object, you must choose whether to expose a custom interface or a dual interface to clients. In PowerBuilder COM objects, both interface types are currently restricted to the use of standard OLE automation datatypes.
Custom interfaces provide access to server object virtual function tables (VTBL), offering higher performance than dispatch-based interfaces and a cleaner usage model than dual interfaces. Consider using a custom interface if the intended client is in a compiled language such as C++ or if you want to take advantage of the support for custom interfaces in a tool such as Visual Basic.
PowerBuilder COM objects that use custom interfaces use the standard marshaling provided by COM.
Dual interfaces allow programmers to call methods in the COM object through virtual function tables as well as through the dispatch interface. They support a wide range of clients and give fast access to methods.
