How to create instance of Win32 COM object?

Question

I have some legacy code that need to port over to C#. There is a COM server object written in C++ that is called by other Win32/MFC apps. I'm trying to see if I can write a C# app and create an instance of the COM object just like the other Win32/MFC apps. I referenced the Type Library (tlb) in my C# project but when I create an instance of the COM server object, I get the following error:

Creating an instance of the COM component with CLSID {723440AD-AB68-11D4-91F9-00A0CCE1FA84} from the IClassFactory failed due to the following error: 80010108 The object invoked has disconnected from its clients. (Exception from HRESULT: 0x80010108 (RPC_E_DISCONNECTED)).

The IDL is as follows:

import "oaidl.idl";
import "ocidl.idl";
[
    object,
    uuid(723440AC-AB68-11D4-91F9-00A0CCE1FA84),
    dual,
    helpstring("ITestServer Interface v2.2"),
    oleautomation,
    pointer_default(unique)
]
interface ITestServer : IDispatch
{
    /* many methods */
}

library MyTestServerLib
{
    importlib("stdole32.tlb");
    importlib("stdole2.tlb");

    coclass TestServer
    {
        [default] interface ITestServer;
    };
}

The legacy apps work fine on my PC so I know that the COM object is registered. It is only my C# app that fails. Any idea as to why I would be getting the error mentioned above?

Any help will be greatly appreciated.

Regards,
LA

Answer 1

I don't reference the .tlb

For example, with a COM interface IImgCtx (used to display pictures) =>

[ComImport]
[Guid("3050F3D7-98B5-11CF-BB82-00AA00BDCE0B")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IImgCtx
{
         // declare all methods...
}

then :

Guid CLSID_IImgCtx = new Guid("3050F3D6-98B5-11CF-BB82-00AA00BDCE0B");
Type ImgCtxType = Type.GetTypeFromCLSID(CLSID_IImgCtx, true);
IImgCtx pImgCtx = (IImgCtx)Activator.CreateInstance(ImgCtxType);