CGI Programming on the World Wide Web

This book offers a comprehensive explanation of CGI and related techniques for people who hold on to the dream of providing their own information servers on the Web.

Good scripting is not limited to a knowledge of CGI -- you need to know something about other programming tools that organize data and make the output look attractive. Gundavaram starts at the beginning, explaining the value of CGI and how it works, and takes you swiftly into the subtle details of programming. The book offers a comprehensive look at the job of providing information dynamically on the Web.

For most of the examples, this book uses the most common platform (UNIX) and the most popular language (Perl) used for CGI programming today. However, it introduces the essentials of making CGI work with other platforms and languages. The actual programming techniques are not too different from one platform and language to another; the lessons from this book can be applied to any tools you choose.

Topics include:

• Basic Perl techniques for parsing and output
• Embedding Server Side Includes (SSI)
• Graphics and simple animation
• Forms and magic cookies
• Gateways and SQL processing
• Internet communications
• Examples of games, imagemap manipulation, and other advanced applications

Table of contents

Preface

1. The Common Gateway Interface (CGI)

What Is CGI?

CGI Applications

Some Working CGI Applications

Internal Workings of CGI

Configuring the Server

Programming in CGI

CGI Considerations

Overview of the Book

2. Input to the Common Gateway Interface

Introduction

Using Environment Variables

Accessing Form Input

Extra Path Information

Other Languages Under UNIX

Other Languages Under Microsoft Windows

Other Languages on Macintosh Servers

Examining Environment Variables

3. Output from the Common Gateway Interface

Overview

CGI and Response Headers

Accept Types and Content Types

The Content-length Header

Server Redirection

The "Expires" and "Pragma" Headers

Status Codes

Complete (Non-Parsed) Headers

4. Forms and CGI

HTML Tags

Sending Data to the Server

Designing Applications Using Forms in Perl

Decoding Forms in Other Languages

5. Server Side Includes 87

Introduction

Configuration

Environment Variables

Including Boilerplates

File Statistics

Executing External Programs

Executing CGI Programs

Tailoring SSI Output

Common Errors

6. Hypermedia Documents 101

Creating Dynamic Home Pages

CGI Examples with PostScript

The gd Graphics Library

CGI Examples with gnuplot

CGI Examples with pgperl

Animation

7. Advanced Form Applications

Guestbook

Survey/Poll and Pie Graphs

Quiz/Test Form Application

Security

8. Multiple Form Interaction

Hidden Fields

CGI Side Includes

Netscape Persistent Cookies

9. Gateways, Databases, and Search/Index Utilities

UNIX Manual Page Gateway

Mail Gateway

Relational Databases

Search/Index Gateway

10. Gateways to Internet Information Servers

Overview

What Are Sockets?

Socket I/O in Perl

Socket Library

Checking Hypertext (HTTP) Links

Archie

Network News on the Web

Magic Cookies

Maintaining State with a Server

Forking/Spawning Child Processes

11. Advanced and Creative CGI Applications

Animated Clock

Game of Concentration

Introduction to Imagemaps

Calendar Manager

12. Debugging and Testing CGI Applications

Common Errors

Programming/System Errors

Environment Variables

Logging and Simulation

CGI Lint-A Debugging/Testing Tool

Set UID/GID Wrapper

A. Perl CGI Programming FAQ

B. Summary of Regular Expressions

C. CGI Modules for Perl 5

D. CGI Lite

E. Applications, Modules, Utilities, and Documentation

Index