CODEWITHSUNDEEP
c#.netcominteropregfreecom
Wayne Bloss
Wayne Bloss

Reputation: 5550

.Net CCW no events with registration-free COM!

I have a COM Callable Wrapper that I'm using from a VB6 program, but the program won't receive COM events unless the CCW is registered. Otherwise, the CCW works fine, just no events until I remove the program's manifest file and register the CCW using "regasm /tlb /codebase theccw.dll". This is in WinXP SP3.

What could be the problem?

Maybe my CCW is built wrong for use as an "early bound" VB6 object. Here are my declarations:

[ComVisible(false)]
public delegate void AnEventDelegate(int arg1);

[
ComVisible(true),
GuidAttribute("XXXX-XXXX-XXXX-XXXX"),
InterfaceType(ComInterfaceType.InterfaceIsIDispatch)
]
public interface IComEvents
{
    void AnEvent(int arg1);
}

[
ComVisible(true),
Guid("YYYY-YYYY-YYYY-YYYY"),
ClassInterface(ClassInterfaceType.None), 
ComSourceInterfaces(typeof(IComEvents))
]
public class TheComClass: IComContract
{
    public TheComClass(){}

    // Implicit implementation of IComContract.
    // Implicit implementation of IComEvents.
    // 
    // eg. public event AnEventDelegate AnEvent;
}

[
ComVisible(true),
Guid("ZZZZ-ZZZZ-ZZZZ-ZZZZ")
]
public interface IComContract
{
    [ComVisible(true)]
    string AProp{ get; set; }

    [ComVisible(true)]
    void AMethod();
}

One thing I just realized. I don't have [ComVisible(true)] attributes on my public event declarations inside of TheComClass. I don't think that's the problem because I do get the events when the thing is registered, but we'll see...

Upvotes: 2

Views: 1053

Answers (3)

Wayne Bloss
Wayne Bloss

Reputation: 5550

The only answer that I found is that this doesn't work and I must register the CCW.

Upvotes: 1

jonathanpeppers
jonathanpeppers

Reputation: 26505

I had the same problem, and figured how to fix it.

Make your class derive from System.Windows.Forms.UserControl.

I have gotten a C# written COM server to use events from VB6, even with registration-free COM.

Apparently UserControl implements IOleObject, which is required for some cases.

Upvotes: 1

AnthonyWJones
AnthonyWJones

Reputation: 189495

In COM events aren't early bound. Where events in .NET are just a specialised usage of the delegates and are ultimately just function calls, COM events are much more involved.

You will need the component registered for events to work.

Upvotes: 1

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