Climbing the CGI Learning Curve

Now that we’ve looked at setup issues, it’s time to get into concrete programming
details. This section is a tutorial that introduces CGI coding one step at a time—from
simple, noninteractive scripts to larger programs that utilize all the common web page
user input devices (what we called widgets in the tkinter GUI chapters in Part III).

Along the way, we’ll also explore the core ideas behind server-side scripting. We’ll move
slowly at first, to learn all the basics; the next chapter will use the ideas presented here
to build up larger and more realistic website examples. For now, let’s work through a
simple CGI tutorial, with just enough HTML thrown in to write basic server-side
scripts.

A First Web Page

As mentioned, CGI scripts are intimately bound up with HTML, so let’s start with a
simple HTML page. The file tutor0.html, shown in Example 15-2, defines a bona fide,
fully functional web page—a text file containing HTML code, which specifies the
structure and contents of a simple web page.

Example 15-2. PP4E\Internet\Web\tutor0.html

A First HTML Page

Hello, HTML World!

If you point your favorite web browser to the Internet address of this file, you should
see a page like that shown in Figure 15-2. This figure shows the Internet Explorer
browser at work on the address http://localhost/tutor0.html (type this into your
browser’s address field), and it assumes that the local web server described in the prior
section is running; other browsers render the page similarly. Since this is a static HTML
file, you’ll get the same result if you simply click on the file’s icon on most platforms,
though its text won’t be delivered by the web server in this mode.

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