Apache::Registry - Run unaltered CGI scrips under mod_perl

 #in httpd.conf

 Alias /perl/ /perl/apache/scripts/ #optional
 PerlModule Apache::Registry

 <Location /perl>
   SetHandler perl-script
   PerlHandler Apache::Registry
   Options ExecCGI 
 </Location>

URIs in the form of CWhttp://www.host.com/perl/file.pl will be compiled as the body of a perl subroutine and executed. Each server process or 'child' will compile the subroutine once and store it in memory. It will recompile it whenever the file is updated on disk. Think of it as an object oriented server with each script implementing a class loaded at runtime.

The file looks much like a normal script, but it is compiled or 'evaled' into a subroutine.

Here's an example:

 my $r = Apache->request;
 $r->content_type("text/html");
 $r->send_http_header;
 $r->print("Hi There!");

This module emulates the CGI environment, allowing programmers to write scripts that run under CGI or mod_perl without change. Existing CGI scripts may require some changes, simply because a CGI script has a very short lifetime of one HTTP request, allowing you to get away with quick and dirty scripting. Using mod_perl and Apache::Registry requires you to be more careful, but it also gives new meaning to the word quick!

Be sure to read all mod_perl related documentation for more details, including instructions for setting up an environment that looks exactly like CGI:

 print "Content-type: text/html\n\n";
 print "Hi There!";

Note that each httpd process or child must compile each script once, so the first request to one server may seem slow, but each request there after will be faster. If your scripts are large and/or make use of many Perl modules, this difference should be noticeable to the human eye.

Apache::Registry::handler will preform the same checks as mod_cgi before running the script.

The Apache function `exit' overrides the Perl core built-in function.

The environment variable GATEWAY_INTERFACE is set to CWCGI-Perl/1.1.

Normally when a Perl script is run from the command line or under CGI, arguments on the `#!' line are passed to the perl interpreter for processing.

Apache::Registry currently only honors the -w switch and will turn on warnings using the CW$^W global variable. Another common switch used with CGI scripts is -T to turn on taint checking. This can only be enabled when the server starts with the configuration directive:

 PerlTaintCheck On

However, if taint checking is not enabled, but the -T switch is seen, Apache::Registry will write a warning to the error_log.

You may set the debug level with the CW$Apache::Registry::Debug bitmask

 1 => log recompile in errorlog
 2 => Apache::Debug::dump in case of $@
 4 => trace pedantically

Apache::Registry makes things look just the CGI environment, however, you must understand that this *is not CGI*. Each httpd child will compile your script into memory and keep it there, whereas CGI will run it once, cleaning out the entire process space. Many times you have heard "always use CW-w, always use CW-w and 'use strict'". This is more important here than anywhere else!

Your scripts cannot contain the __END__ or __DATA__ token to terminate compilation.

perl(1), mod_perl(3), Apache(3), Apache::Debug(3)

Andreas J. Koenig and Doug MacEachern