What better way to learn about CGI than to see actual programs in action? Here are the locations of some of the more impressive CGI programs on the Web:
Located at http://www.lycos.com, this server allows the user to search the Web for specific documents. Lycos returns a dynamic hypertext document containing the documents that match the user's search criteria.
An entertaining application that displays an image for users to color. It can be accessed at http://www.ravenna.com/coloring.
A gateway to the Archie search server. Allows the user to search for a specific string and returns a virtual hypertext document. This useful gateway is located at http://pubweb.nexor.co.uk/public/archie/archieplex/archieplex.html. A simple Archie gateway is presented in Chapter 10, Gateways to Internet Information Servers.
A guestbook is a forms-based application that allows users to leave messages for everyone to see. Though there are numerous guestbooks on the Web, this is one of the best. You can access it at http://www.cosy.sbg.ac.at/rec/guestbook.
A sophisticated CGI program that queries the user for an English word, and returns a virtual document with graphic images of an equivalent Japanese word, or vice versa. It can be accessed at http://www.wg.omron.co.jp/cgi-bin/je?SASE=jfiedl.html or at http://enterprise.ic.gc.ca/cgi-bin/j-e.
Although most of these documents are curiosities, they illustrate the powerful aspects of CGI. The interface allows for the creation of highly effective virtual documents using forms and gateways.