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Chapter 15. Web Server Programming with mod_perl
Contents:
Installing mod_perl
Design of mod_perl
mod_perl Handlers
Running CGI Scripts with mod_perl
Server Side Includes with mod_perl
<Perl> Sections
Apache:: Modules
The Perl API
mod_perl is an Apache module that embeds the Perl interpreter directly into Apache. There are many advantages to mod_perl:
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Standard CGI programs can be converted to run significantly faster with little alteration under mod_perl.
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Databases can be accessed much more efficiently under mod_perl.
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You can write custom Apache modules and handlers easily, using Perl instead of C. mod_perl gives you access to all Apache request stages.
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Perl code can be embedded into Apache configuration files.
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Perl can be used for server-side includes.
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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.
15.1. Installing mod_perl
If you already have Apache installed on your machine, you will have to rebuild it with mod_perl. You can get the source and documentation for mod_perl from http://perl.apache.org/. If there isn't already an Apache httpd in the Apache source tree, you must build one. Then build mod_perl as directed in the INSTALL file for the mod_perl distribution.
As we've mentioned, mod_perl allows you to hook in Perl modules as handlers for various stages of a request. By default, however, the only callback hook that is enabled is PerlHandler, which is the one that processes content (i.e., a CGI document). If you want to use other hooks—for example, to extend Apache's logging facilities via the PerlLogHandler directive; you need to specify it at build time as directed in the INSTALL file. For example:
% perl Makefile.PL PERL_LOG=1
The mod_perl Makefile replaces the httpd in the Apache source tree with a Perl-enabled one. When you install mod_perl, it installs not only the new httpd in your system area, but also several Perl modules, including Apache::Registry.
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| 14.7. CGI.pm Reference |  | 15.2. Design of mod_perl |
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