next up previous contents
Next: Writing CGI scripts Up: Server Scripts Previous: Server Scripts

Common Gateway Interface (CGI)

CGI, the Common Gateway Interface, is a standardised way of writing scripts that the server will run when a request for the relevant URL is received. A gateway is typically a program that transforms information from one form to another, and one use for CGI scripts is to implement gateways. For example, you may have all your data in a relational database, and want to make this information available to the Web. To do this you would write a gateway script to transform HTTP requests into accesses to your database, and translate the replies into HTML.

Before CGI, each server passed the query information into a script in its own way. Unfortunately this made it difficult to write gateways that would work on more than one type of server, so a few of the server developers got together and CGI was the result. Some servers don't yet support CGI, but most of the popular ones now do.

Jon Crowcroft
Wed May 10 11:46:29 BST 1995