Practical mod_perl

Chapter 1. Introducing CGI and mod_perl

This chapter provides the foundations on which the rest of the book builds. In this chapter, we give you:

• A history of CGI and the HTTP protocol.

• An explanation of the Apache 1.3 Unix model, which is crucial to understanding how mod_perl 1.0 works.

• An overall picture of mod_perl 1.0 and its development.

• An overview of the difference between the Apache C API, the Apache Perl API (i.e., the mod_perl API), and CGI compatibility. We will also introduce the Apache::Registry and Apache::PerlRun modules.

• An introduction to the mod_perl API and handlers.

A Brief History of CGI

When the World Wide Web was born, there was only one web server and one web client. The httpd web server was developed by the Centre d’Etudes et de Recherche Nucléaires (CERN) in Geneva, Switzerland. httpd has since become the generic name of the binary executable of many web servers. When CERN stopped funding the development of httpd, it was taken over by the Software Development Group of the National Center for Supercomputing Applications (NCSA). The NCSA also produced Mosaic, the first web browser, whose developers later went on to write the Netscape client.

Mosaic could fetch and view static documents^[1] and images served by the httpd server. This provided a far better means of disseminating information to large numbers of people than sending each person an email. However, the glut of online resources soon made search engines necessary, which meant that users needed to be ...