CHAPTER 11

CGI Application 

Modules for CPAN

C

OMMON

 G

ATEWAY

 I

NTERFACE

 (CGI) programming is probably the most common 

use for the Perl language. CGI provides the interactivity in nearly every popular site 

on the Web today. Although CGI is an old technology by Internet standards, what it 

lacks in sex appeal it more than makes up for in utility and portability. Unlike the 

many CGI replacement technologies available, it is supported on virtually every 

platform and Web server. If you can use Perl on your platform of choice, the 

chances are excellent that you can use CGI too.

CGI::Application

1

 provides a new and better way to build CGI programs as 

reusable modules. Since CGI::Application modules are normal Perl modules, they 

can be released on CPAN and reused by the Perl community. This chapter will 

introduce you to CGI::Application and explore the ways in which it encourages 

software reuse.

One thing this chapter won't do is teach you CGI programming or explain how 

to use CGI.pm. To get the most out of this chapter, you'll need some prior expe 

rience with CGI. If you're new to the technology, then you should consider reading 

a good book on the topic first.

2

Introduction to CGI::Application

The CGI::Application module represents an evolution in the way CGI programs 

(known as CGIs) are developed. CGIs provide services to users through their Web 

browsers, usually by displaying a series of screens containing forms for the user to 

interact with. CGIs are commonly coded in Perl by creating a script that generates 

HTML forms and processes the results of those forms. There are many drawbacks 

to this approach, as I'll explain in the upcoming text.

CGI::Application offers a different model. Instead of writing your CGI code in 

scripts specific to the task at hand, CGI::Application allows you to create flexible 

1. Written by Jesse Erlbaum, the technical editor for this book. You can find it on CPAN, of course!

2.  There are many books written about this subject. A favorite of mine is CGI Programming 

with Perl, 2nd Edition by Guelich, Gundavaram, and Birznieks (O'Reilly & Associates).

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