Working with Web Forms

Web forms are based on ASP.NET (ASP stands for Active Server Pages). Visual Basic will handle the details of working with ASP.NET for us, so in the end, it feels much like you're working with a standard Windows Visual Basic project. But the difference is that you're creating a Web page or pages that can be accessed by any browser on the Internet. These Web pages are given the extension .aspx, so, for example, if your program is called CalculateRates, you might end up simply directing users to a Web page called CalculateRates.aspx, which they can open in their browsers.

To create Web applications, you'll need a computer with the Microsoft Internet Information Services (IIS) version 5.0 or later installed (either locally or on a remote server).

IIS must be running on a Windows machine with the .NET framework installed so your Visual Basic code can run. Note that for development purposes, you can use IIS locally if you install it on the same machine that you develop programs on. (IIS comes pre-installed in some Windows operating systems like Windows 2000 Server, and it comes on the CDs for it, but still has to be installed in others, such as Windows 2000 Professional.)

The Web forms you create need not run in Internet Explorer, but if they don't, a number of features will usually be disabled, because they need Internet Explorer to work (see the topic "Detecting Browser Type and Capabilities" in the Immediate Solutions section of this chapter). In Web forms, the user interface programming is divided into two distinct pieces: the visual component, which is the Web page itself (this can include scripting code, such as JavaScript—or JScript, the Internet Explorer equivalent—to run in the browser), and the Visual Basic code behind that page (which runs on the server). The visual component has the extension .aspx, and the code that runs on the server has the extension .aspx.vb.