11.1. Design of mod_perl

mod_perl is a Perl runtime library linked into the Apache server. With mod_perl, the Perl programmer has access to Apache's C language API through an object-oriented Perl interface. This means that you can write Apache modules and extensions entirely in Perl and embed Perl code and custom directives in your Apache configuration files. Furthermore, the embedded Perl interpreter removes the overhead that you'd experience if you'd merely written a Perl CGI program and put it in Apache's cgi-bin.

Aside from the framework mentioned above, another major benefit of mod_perl is the Apache::Registry module. Apache::Registry implements the CGI environment under the mod_perl framework, which means that you can reuse most of your existing Perl CGI programs to realize the benefits of mod_perl. Apache::Registry caches compiled scripts on the first execution of a script and updates scripts that have changed on disk.