PSGI

PSGI or Perl Web Server Gateway Interface is an interface between Web servers and Perl-based Web applications and frameworks that allows writing portable applications that can be run as standalone servers or using CGI, FastCGI, mod_perl, et al. It is inspired by the Web Server Gateway Interface for Python, Rack for Ruby and JSGI for JavaScript.

A PSGI application is a Perl subroutine that accepts arguments as a single hash reference and returns a reference to an array of three elements: an HTTP status code, a reference to an array of HTTP headers and a reference to an array of HTTP body lines (usually a generated HTML document) or a filehandle-like object.

Plack is a reference PSGI implementation.

Web frameworks with PSGI support:

• Catalyst
• CGI::Application
• Continuity
• Dancer
• HTTP::Engine
• Mason
• Maypole
• Mojolicious
• Piglet
• Squatting
• Starman
• Tatsumaki

Example Application

This is an example hello world PSGI application:

my $app = sub {
    return [200, ['Content-Type' => 'text/plain'], ["hello, world\n"]];
}

External links

• Plack and PSGI, various links to servers and frameworks
• PSGI - Perl Web Server Gateway Interface Specification
• article on Plack and nginx from Catalyzed.org
• Plack Advent calendar
• Plack coverage, Catalyst Advent calendar