CF COM Interop #1 FAQ

Fri, May 20, 2005, 02:15 PM under MobileAndEmbedded
Now that NETCF 2.0 supports COM Interop (for CF 1.0 your best bet is 3rd party support), there is a FAQ emerging.

Q: I have a native/C++ exe/process and cannot get it to talk to my managed/C#/VB dll/class library. What's wrong?
A: As indicated last year, this is not supported.

To help Google get you here, I will use various phraseologies that all indicate the same thing.

You can call native COM components from managed code, as long as it is from a managed exe - VS will generate the RCW (Remote Callable Wraper) for you. Once you have activated native COM objects from managed code, they can call you back; so in that sense - and that sense only - CCW (COM Callable Wrappers) are supported.

You cannot activate (or register) managed objects through COM. Regasm.exe that the full framework supports is not available. Forget doing a CoCreate on your managed objects.

If you think about the last statement it makes sense, since runtime hosting of the NETCF CLR is not supported; how could you start a native process that "talked" to a managed library (dll)?

Incidentally, if you must communicate from native code to managed code and since you cannot do that in the same process, consider one of the IPC mechanisms available on WinCE.

While we are on the subject of NETCF 2.0 COM Interop limitations, allow me to quote from one of Richard Greenberg's slides from MEDC:
"Only MTAs (multi-threaded apartments) are supported and there are no custom marshalers or auto-generated Class Interfaces."
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