Interop VB 6.0 and VB.NET

One of the questions I frequently get is how to upgrade from VB 6 to VB.NET. Though there are lot of upgrade scenerios explained in detail in MSDN, my favourite has always been step-by-step upgrade. In this approach, you take one of your existing forms, upgrade/re-develop them in VB.NET and have it being called from VB 6.0 applications. Then you move to the next form, by doing this, over a period you can have the entire application moved to VB.NET. The problem in doing this was to have the knowledge on how to turn the VB.NET form into a COM component that can be called from VB 6.0, MS has made this easier now with Interop Forms Toolkit 1.0.

Having the forms developed in VB.NET brings in lot of capabilities – foremost being the ability to support 100% Unicode, which is very important for Indic Languages like Tamil, Hindi, etc.

For doing Unicode with VB 6.0:

Though basic: If Windows XP / 2003 – First ensure you have selected the check box in Control Panel -> Regional and Languages Options -> Languages Tab -> Install Files for Complex Script and Right Languages (or) If Windows 2000 – Ensure you have Indic Support enabled

VB 6.0 even with MS Forms 2.0 will have some issues with Unicode, especially Indic languages like Tamil. I found it easier and better to do the forms in VB.NET 1.1 and then call the forms from VB 6.0. So the .NET application can be either a standalone EXE (or) called as a ActiveX COM DLL .

These references might be useful, check them out: