What Is Common Gateway Interface (CGI)?

This section describes what is CGI (Common Gateway Interface) - a protocol defines how a Web server program interacts with application programs.

Common Gateway Interface (CGI) is a protocol that defines how a Web server program interacts with application programs. The interactions are illustrated in the following diagram:

Web                  Web      CGI        Appl.
Browser   Internet   Server   Protocol   Program  
          HTTP                Env. Var.
          request             stdin
Send --------------> Convert ----------> Process
                                            |
          HTTP                              |
          response            stdout        V
Receive <----------- Convert <---------- Process

There are several basic rules with CGI:

Table of Contents

 About This Book

 Perl on Linux Systems

 ActivePerl on Windows Systems

 Data Types: Values and Variables

 Expressions, Operations and Simple Statements

 User Defined Subroutines

 Perl Built-in Debugger

 Name Spaces and Perl Module Files

 Symbolic (or Soft) References

 Hard References - Addresses of Memory Objects

 Objects (or References) and Classes (or Packages)

 Typeglob and Importing Identifiers from Other Packages

 String Built-in Functions and Performance

 File Handles and Data Input/Output

 Open Files in Binary Mode

 Open Directories and Read File Names

 File System Functions and Operations

 Converting Perl Script to Executable Binary

 Using DBM Database Files

 Using MySQL Database Server

 Socket Communication Over the Internet

 XML::Simple Module - XML Parser and Generator

 XML Communication Model

 SOAP::Lite - SOAP Server-Client Communication Module

 Perl Programs as IIS Server CGI Scripts

CGI (Common Gateway Interface)

What Is Common Gateway Interface (CGI)?

 IIS Environment Variables

 QUERY_STRING - CGI Query String

 Calculator.pl - CGI Application Example

 XML-RPC - Remote Procedure Call with XML and HTTP

 RPC::XML - Perl Implementation of XML-RPC

 Integrating Perl with Apache Web Server

 CGI.pm Module for Building Web Pages

 LWP::UserAgent and Web Site Testing

 References

 PDF Printing Version