Re: Making asynchronous calls

"Alexander Nickolov" <>
Mon, 19 Nov 2007 08:58:10 -0800
Don't try that with a DLL - make it an EXE. Async COM only
works across COM apartment boundaries and with a DLL you
must make sure your threading model is incompatible with the
threading model of the DLL (e.g. this won't work at all if the DLL
is marked as ThreadingModel=Both). The only reliable choice
is an out-of-proc EXE server.

Alexander Nickolov
Microsoft MVP [VC], MCSD

"venky" <> wrote in message

Hi !
I`m having serious trouble in implementing nonblocking calls to a COM
DLL. I created a COM DLL using the ATL wizard as follows : Threading
Model - "Both", Aggregation - "No", Interface- "Custom". I created the
project with 'Merge Proxy/Stub" option enabled
As per MSDN documentation, I added a async_uuid() attribute and could
see that Begin_ and Finish_ methods were created.
But i`m not able to invoke the call from the client side. My code is
as follows:

ItryInterface* pObj=0;

hr = CoCreateInstance(CLSID_tryInterface, 0, CLSCTX_SERVER,
               IID_ItryInterface, (void**)&pObj);

     // Query the object for ICallFactory
  ICallFactory* pCf=0;
  hr = pObj->QueryInterface(IID_ICallFactory,

// At this point it fails with E_NOINTERFACE error. Isin`t it
mentioned in MSDN, that adding async_uuid() will automatically
implement ICallFactory for that interface.. ? Then why the error ?

Please help ! I`m totally exasperated !!!!


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