C# 4 and .NET 4

712 ❘ ChaPTer 26 interOp
//.
public:
BEGIN_CONNECTION_POINT_MAP(CCOMDemo)
CONNECTION_POINT_ENTRY(__uuidof(_ICompletedEvents))
END_CONNECTION_POINT_MAP()
};
code snippet COMServer/COMDemo.h
Finally, the method Fire_Completed() from the proxy class can be called inside the methods Add() and
Sub() in the file COMDemo.cpp:
STDMETHODIMP CCOMDemo::Add(LONG val1, LONG val2, LONG* result)
{
*result = val1 + val2;
Fire_Completed();
return S_OK;
}
STDMETHODIMP CCOMDemo::Sub(LONG val1, LONG val2, LONG* result)
{
*result = val1 - val2;
Fire_Completed();
return S_OK;
}
code snippet COMServer/COMDemo.cpp
After rebuilding the COM DLL, you can change the .NET client to use these COM events just like a normal
.NET event:
static void Main()
{
COMDemo obj = new COMDemo();
IWelcome welcome = obj;
Console.WriteLine(welcome.Greeting("Stephanie"));
obj.Completed += () => Console.WriteLine("Calculation completed");
IMath math = (IMath)welcome;
int result = math.Add(3, 5);
Console.WriteLine(result);
}
Marshal.ReleaseComObject(math);
code snippet DotnetClient/Program.cs
As you can see, the RCW offers automatic mapping from COM events to .NET events. COM events can be
used similarly to .NET events in a .NET client.
tsing a .neT ComPonenT from a Com ClienT
So far, you have seen how to access a COM component from a .NET client. Equally interesting is to find a
solution for accessing .NET components on an old COM client that is using Visual Basic 6.0, or C++ with
MFC (Microsoft Foundation Classes), or ATL.
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