I might have found an example that cracks the problem for me. One sample has this:
ITicketCallBack callback =
OperationContext.Current.GetCallbackChannel
<ITicketCallBack>();
So he gets the callback out of the operation context when the client makes a
call to "register" itself. I'll do the same thing, and it seems to make
sense, although the service attributes have to be set carefully to get the
required behaviour. Off I go coding...
Greg
