The following figure shows the typical Smalltalk DDE architecture.
Either one of these objects could be any other application that supports the
DDE protocol for either a DDE server or a DDE client.
The classes depicted in the figure are described in the following
sections. Their hierarchy is as follows:
Object
DdeClass
DdeClient
DdeServer
DdeServerManager
This hierarchy is not part of the windowing system (such as PM or Windows) but it does use the windowing system of the underlying platform.