Using Visual Basic 6 with Visual Basic .NET: COM Interop This chapter focuses on making your Visual Basic 6 and Visual Basic .NETapplications work together. The mechanism that makes interoperabilitybetween the two products possible is known as COM interop. We’ll start bylooking at the various ways you can create or use existing components thatcommunicate across COM and .NET component boundaries. We’ll also showyou how to debug across calls between Visual Basic 6 and Visual Basic .NETauthored components. Finally, we’ll discuss the role of binary compatibility inVisual Basic .NET. If you’ve been creating multitiered applications using Visual Basic 6, your application has likely evolved into a large system spanning multiple compo-nents. Let’s say, for example, that you have an application composed of a VisualBasic standard EXE front end containing ActiveX controls talking to a middle-tier Visual Basic DLL. The Visual Basic DLL in turn talks to a back-end SQLServer database. Upgrading such an application to Visual Basic .NET in oneshot is nearly impossible. This is where COM interop swoops in to save the day