Scroll to navigation

CGI::Emulate::PSGI(3pm) User Contributed Perl Documentation CGI::Emulate::PSGI(3pm)


CGI::Emulate::PSGI - PSGI adapter for CGI


    my $app = CGI::Emulate::PSGI->handler(sub {
        # Existing CGI code


This module allows an application designed for the CGI environment to run in a PSGI environment, and thus on any of the backends that PSGI supports.

It works by translating the environment provided by the PSGI specification to one expected by the CGI specification. Likewise, it captures output as it would be prepared for the CGI standard, and translates it to the format expected for the PSGI standard using CGI::Parse::PSGI module.

If your application uses CGI, be sure to cleanup the global variables in the handler loop yourself, so:

    my $app = CGI::Emulate::PSGI->handler(sub {
        use CGI;
        my $q = CGI->new;
        # ...

Otherwise previous request variables will be reused in the new requests.

Alternatively, you can install and use CGI::Compile from CPAN and compiles your existing CGI scripts into a sub that is perfectly ready to be converted to PSGI application using this module.

  my $sub = CGI::Compile->compile("/path/to/script.cgi");
  my $app = CGI::Emulate::PSGI->handler($sub);

This will take care of assigning a unique namespace for each script etc. See CGI::Compile for details.

You can also consider using CGI::PSGI but that would require you to slightly change your code from:

  my $q = CGI->new;
  # ...
  print $q->header, $output;


  use CGI::PSGI;
  my $app = sub {
      my $env = shift;
      my $q = CGI::PSGI->new($env);
      # ...
      return [ $q->psgi_header, [ $output ] ];

See CGI::PSGI for details.


  my $app = CGI::Emulate::PSGI->handler($code);

Creates a PSGI application code reference out of CGI code reference.

  my %env = CGI::Emulate::PSGI->emulate_environment($env);

Creates an environment hash out of PSGI environment hash. If your code or framework just needs an environment variable emulation, use this method like:

  local %ENV = (%ENV, CGI::Emulate::PSGI->emulate_environment($env));
  # run your application

If you use "handler" method to create a PSGI environment hash, this is automatically called in the created application.


Tokuhiro Matsuno <>

Tatsuhiko Miyagawa


Copyright (c) 2009-2010 by tokuhirom.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.


PSGI CGI::Compile CGI::PSGI Plack CGI::Parse::PSGI

2022-06-09 perl v5.34.0