What most people want to do with mod_perl is improve
The mod_perl installation assumes this request by enabling the
callback hook by default, and by installing the Apache::Registry module.
PerlHandler is the handler used for the content retrieval stage of the
Apache::Registry is the
Perl module that emulates the CGI environment so you can use
"standard" Perl CGI scripts with mod_perl without
having to rewrite them (much). This is by far the cheapest way to get
improved CGI performance.
With Apache::Registry, each individual CGI program is compiled and cached the first time it is called (or whenever it is changed), and then remains available for all subsequent instances of that CGI script. This process avoids the costs of startup time.
Whereas most CGI scripts are kept in /cgi-bin/, scripts that use Apache::Registry are placed in a separate directory, e.g., /perl-bin/. The access.conf Apache configuration file needs to point to this directory by setting an alias and defining a handler for this new location.
Instead of using theAlias /perl-bin/ /usr/local/apache/perl-bin/ <Location /perl-bin> SetHandler perl-script PerlHandler Apache::Registry PerlSendHeader On Options ExecCGI </Location>
cgi-scripthandler, we use the
perl-scripthandler to give control to mod_perl. Next, the
PerlHandlerdirective tells mod_perl that the Apache::Registry module should be used for serving all files in that directory.
PerlSendHeaderis another mod_perl-specific directive; in this case, it tells mod_perl to send response lines and common headers - by default, none are sent. (For NPH scripts, you'll want to turn this feature off again.)
Options ExecCGIis a standard Apache header needed to tell Apache to treat the script as a CGI script.
If you include this line, you shouldn't need to explicitlyPerlModule CGI
use CGIin each Perl CGI script anymore, as CGI.pm will be loaded directly from the Apache server. Up to ten modules can be listed with the
CGI scripts in the new directory should work now. However, if you have problems, the mod_perl manpage offers some words of wisdom:
"Standard" CGI scripts start with a clean slate every time.
When switching to mod_perl, CGI programmers are often
surprised to learn how often
they take advantage of this fact.
tells you when your variables haven't been properly declared
and might inherit values from previous invocations of the script.
exit() at the end of every program is a habit
of many programmers. While often totally unnecessary, it
usually doesn't hurt...except with mod_perl.
If you're using mod_perl without Apache::Registry,
exit() kills the server
exit() is the
last function call, you can just remove it.
If the structure of your program is such that it is called
from the middle of the script, you can just put a label
at the end of the script and use
Apache->exit() call you can use if you're
really attached to
If you're using Apache::Registry, you don't
have to worry about this problem. Apache::Registry is
smart enough to override all
exit() calls with
In addition, it is recommended that you should use a recent version of Perl and of CGI.pm. You should scan the mod_perl documentation for the very latest compatibility news.