CGI Scripting

One way to enhance the interaction between user and content is to have the page communicate with the Web server that houses the Web pages. Popular Web search sites, such as Yahoo!, Google, and Lycos, enable users to type search criteria and click a button or two to specify the way the search engine should treat the query.

E-commerce sites enable you to gather products in a virtual shopping cart and then click a button to submit an order for processing. When you click the Submit or Search buttons, your browser sends your entries from a form to the server. On the server, a program known as a CGI (Common Gateway Interface) script formats the data you enter and sends this information to a database or other program running on the server. The CGI script then sends the results to your browser, sometimes in the form of a new page or as information occupying other fields in the form.

Writing customized CGI scripts typically requires considerable programming skill. Most CGI scripts are written in languages such as Perl, Java, and C or C++. Very few servers are equipped to run server scripts written in JavaScript. Whatever language you use, the job definitely requires the Web page author to be in control of the server, including whatever back-end programs (such as databases) are needed to supply results or massage the information coming from the user. Even with the new, server-based Web site design tools available, CGI scripting often is not a task that a content-oriented HTML author can do without handing it off to a more experienced programmer.

As interesting and useful as CGI scripting is, it burdens the server with the job of processing queries. A busy server may process hundreds of CGI scripts at a time, while the client computers—the personal computers running the browsers—sit idle as the browser’s logo icon dances its little animation. This wastes desktop processing horsepower, especially if the process running on the server doesn’t need to access big databases or other external computers. That’s why some people regard browsing a basic Web page as little more than using a dumb terminal to access some server content.