Oh, I never have used them. I just searched and found good articles. For the C# becoming a COM object, that's fairly easy since it's a MS supported feature to make them interoperable. For the C# to Java Interop, it's a little more tricky. I don't know exactly yet how to do it but reading up on it, it appeared easier than going C++. But I could be wrong. Let me know if you find anything.