Ubuntu Manpage: ModPerl::Registry - Run unaltered CGI scripts persistently under mod

Provided by: libapache2-mod-perl2_2.0.8+httpd24-r1449661-6ubuntu2.1_amd64

NAME

       ModPerl::Registry - Run unaltered CGI scripts persistently under mod_perl

Synopsis

         # httpd.conf
         PerlModule ModPerl::Registry
         Alias /perl/ /home/httpd/perl/
         <Location /perl>
             SetHandler perl-script
             PerlResponseHandler ModPerl::Registry
             #PerlOptions +ParseHeaders
             #PerlOptions -GlobalRequest
             Options +ExecCGI
         </Location>

Description

URIs in the form of "http://example.com/perl/test.pl" will be compiled as the body of a Perl subroutine
and executed. Each child process will compile the subroutine once and store it in memory. It will
recompile it whenever the file (e.g. test.pl in our example) 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 into a subroutine.

For example:

my $r = Apache2::RequestUtil->request;
$r->content_type("text/html");
$r->print("mod_perl rules!");

XXX: STOPPED here. Below is the old Apache::Registry document which I haven't worked through yet.

META: document that for now we don't chdir() into the script's dir, because it affects the whole process
under threads. "ModPerl::RegistryPrefork" should be used by those who run only under prefork MPM.

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 ModPerl::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.

DirectoryIndex

       If you are trying setup a DirectoryIndex under a Location covered by ModPerl::Registry* you might run
       into some trouble.

       META: if this gets added to core, replace with real documenation.  See
       http://marc.theaimsgroup.com/?l=apache-modperl&m=112805393100758&w=2

Special Blocks

   "BEGIN" Blocks
       "BEGIN" blocks defined in scripts running under the "ModPerl::Registry" handler behave similarly to the
       normal mod_perl handlers plus:

       •   Only once, if pulled in by the parent process via "Apache2::RegistryLoader".

       •   An  additional time, once per child process or Perl interpreter, each time the script file changes on
           disk.

       "BEGIN" blocks defined in modules loaded from  "ModPerl::Registry"  scripts  behave  identically  to  the
       normal mod_perl handlers, regardless of whether they define a package or not.

   "CHECK" and "INIT" Blocks
       Same as normal mod_perl handlers.

   "END" Blocks
       "END"  blocks  encountered  during compilation of a script, are called after the script has completed its
       run, including subsequent invocations when the script is cached in memory.  This  is  assuming  that  the
       script  itself  doesn't  define  a  package  on its own. If the script defines its own package, the "END"
       blocks in the scope of that package will be executed at the end of the interpretor's life.

       "END" blocks residing in modules loaded  by  registry  script  will  be  executed  only  once,  when  the
       interpreter exits.

Security

       "ModPerl::Registry::handler" performs the same sanity checks as mod_cgi does, before running the script.

Environment

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

Commandline Switches In First Line

       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.

       "ModPerl::Registry" currently only honors the -w switch and will enable the  "warnings"  pragma  in  such
       case.

       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:

        PerlSwitches -T

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

Debugging

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

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

Caveats

       ModPerl::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 "-w", always use
       "-w" and 'use strict'".  This is more important here than anywhere else!  Some other important caveats to
       keep in mind are discussed on the Perl Reference page.

Authors

       Andreas J. Koenig, Doug MacEachern and Stas Bekman.