Question

I’m exposing a C# class to COM using these attributes:

[ComVisible(true)]
[ClassInterface(ClassInterfaceType.AutoDual)]
[GuidAttribute("2325EBEB-DB5F-4D29-B220-64845379D9C5")]
[ComSourceInterfaces(typeof(WrapperEvents))]

in this class I have a function:

public void shutdownService()

This function is meant to be called just once from a VB6 client via COM Interop. Everything works fine. But somehow, it’s being called more than once. My C# codes doesn’t call this function directly. So I’m guessing the problem is in VB6 code. Unfortunately, that’s not what the VB6 team thinks.
Is there a way to determine the caller of this function, ie. from my C#code or the VB6 code?

Right now I’m using a simple function to get the stacktrace:

    public void LogStack()
    {
        var trace = new System.Diagnostics.StackTrace();
        foreach (var frame in trace.GetFrames())
        {
            var method = frame.GetMethod();
            if (method.Name.Equals("LogStack")) continue;
            logger.Debug(string.Format("LogStack: {0}::{1}",
                method.ReflectedType != null ? method.ReflectedType.Name : string.Empty, method.Name));
        }
    }

Obviously, I got somthing like this on the log:

2011-12-23 08:28:40,067 1          DEBUG (null) LogStack: Service::shutdownService

Since the only line of LogStack is the COM exposed function, I assume it’s being called from vb6. But that’s not enough proof for the VB6 team. Any idea how to really prove where function ?

Answer 1

You can try several things:

• set a breakpoint in your code to trigger the debugger, then look at the call stack.
  You could do an application dump here from visual studio and send it to them or screenshot the stack.

ex. Debugger.Break

http://www.netsplore.com/PublicPortal/blog.aspx?EntryID=12

Dump with “Savre Dump As”
http://msdn.microsoft.com/en-us/library/d5zhxt22.aspx

• Use the com tracing
  from a system level see
  http://support.microsoft.com/kb/926098

I also recall a tool being installed with visual studio 6 do to this as well