Chapter 15. Web Server Programming with mod_perl

mod_perl is an Apache module that embeds the Perl interpreter directly into Apache. There are many advantages to mod_perl:

• Standard CGI programs can be converted to run significantly faster with little alteration under mod_perl.

• Databases can be accessed much more efficiently under mod_perl.

• You can write custom Apache modules and handlers easily, using Perl instead of C. mod_perl gives you access to all Apache request stages.

• Perl code can be embedded into Apache configuration files.

• Perl can be used for server-side includes.

• You have access to the many tools written for mod_perl servers, such as Mason and AxKit.

mod_perl isn't for everyone. By embedding Perl directly into the Apache httpd executable, mod_perl invokes significant overhead of its own. If you only have static documents, you certainly wouldn't use a mod_perl-enabled version of Apache to serve them. However, if you have a lot of dynamic content, you'll find mod_perl to be extremely powerful. You can also have the best of both worlds by designing your web site to serve static documents off a "normal" Apache server and dynamic documents off a mod_perl server.

At this writing, the release of mod_perl 2.0 is imminent, but mod_perl 1.3 is considered the stable version. mod_perl 2.0 is a near-complete rewrite that takes advantage of the threading features in Apache 2.0 and Perl 5.8. However, mod_perl 2.0 is still considered experimental. As the migration period to mod_perl 2.0 is expected to be long, this chapter covers mod_perl 1.3.