I am running into a problem where I am passing COM interface pointers from one EXE process into another (VB) EXE process. In turn, this VB EXE is spawning my ATL based dll - supplying my dll with the COM interface pointers that originated in another EXE. There seems to be a marshalling problem, since some of the interface pointers are viewed as NULL by my dll. Whereas, if my parent VB component is built as a dll rather than as a Active X EXE - everything works fine (no NULL interface pointers).

Any ideas on how I can resolve this problem?

Thank you.
Alan

I think the problem is that EXEs run in their own memory space. The interface pointers are relative to the memory space of the EXE that creates them, so when you pass them to another EXE they no longer point to the same place (because they are then assumed to be relative to the 2nd EXE). That would explain why it works from a DLL (DLLs run in the same memory space as the caller).

To solve it you would need to find the offset too, so you could point from the 2nd EXE into the memory space of the 1st EXE.

All sounds a bit iffy to me...can't you get the interfaces directly in your ATL DLL without having to pass in an explicit pointer?

rgds
Phil

Phil

Thanks for your reply. I am not sure how one goes about finding the "offset pointers" as you indicated. The explicit pointers are required since they point to data that is contained by the originating EXE.

Alan

Well I'm not sure how you can do this stuff using VB (which uses Single Threaded Apartment model) but maybe look at this article for starters:
http://msdn.microsoft.com/library/en...nthrd_68s3.asp
hth
Phil