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>>I was thinking in terms of VFP pier-to-pier (apartment threaded?) COM. If two clients instanciate the same server, could the server be used to pass (push) a message from one of the clients to the other? I've had some experience with
>>languages that offer an HWND port.
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>No. It won't be apartment model threaded. You have to run the DLL under MTS or COM+ to get that.
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>And, it doesn't work the way you want. The DLL runs in the process space of the EXE that is hosting it.
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>>I guess I am trying to understand if a server can be "aware" of the clients
>>holding it's object reference, and can the server direct mesaages (providing a push mechanism is in place) to a specific client.
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>I don't think you can do that. What exactly are you trying to accomplish? Maybe there is another way to make it work.

I would say - yes, you can do it. I finished the first working prototype of my new COM Communicator class at 3:00 AM last night. So far I experimented with multi-use out-of-process version. It is done through raising the events - this is the "push mechanism".
I will experiment more with different versions and if everything works as I expect it, I will add this as a bonus sample for my DevCon session.