Introduction

Now that we have seen how to develop an application with Visual Basic .NET, what about your existing applications? Do you leave them as is, or should you upgrade them? There are different factors to consider when making this decision. This chapter will focus on when to upgrade your application, and what is involved in an upgrade when you decide to do it.

The .NET architecture is different from previous versions of Visual Basic and some applications will require significant changes. Visual Basic .NET has transitioned to making everything an object, prompting significant programming changes. You will have to modify data types to match the new Common Type System (CTS), which will impact applications using the Variant data type. There are other considerations. Some keywords have been changed or even removed, and your Visual Basic Forms will need to be upgraded to Windows Forms. Error handling will be completely different as well, and you will have to convert all existing error handling to the new exception-based format.

As you have seen, data access has changed drastically and is based on XML. This is a major paradigm shift, and addressing these issues can take considerable time and effort. Interfaces and events have changed from previous versions of Visual Basic. Not all applications use these features, but you need to understand how to convert them if they do. Fortunately, Microsoft has created an upgrade tool. This will attempt to upgrade your application from Visual Basic 6.0 to Visual Basic .NET. Of...