NAME¶
Plack - Perl Superglue for Web frameworks and Web Servers (PSGI toolkit)
DESCRIPTION¶
Plack is a set of tools for using the PSGI stack. It contains middleware
components, a reference server and utilities for Web application frameworks.
Plack is like Ruby's Rack or Python's Paste for WSGI.
See PSGI for the PSGI specification and PSGI::FAQ to know what PSGI and Plack
are and why we need them.
MODULES AND UTILITIES¶
Plack::Handler¶
Plack::Handler and its subclasses contains adapters for web servers. We have
adapters for the built-in standalone web server HTTP::Server::PSGI, CGI, FCGI,
Apache1, Apache2 and HTTP::Server::Simple included in the core Plack
distribution.
There are also many HTTP server implementations on CPAN that have Plack
handlers.
See Plack::Handler when writing your own adapters.
Plack::Loader¶
Plack::Loader is a loader to load one Plack::Handler adapter and run a PSGI
application code reference with it.
Plack::Util¶
Plack::Util contains a lot of utility functions for server implementors as well
as middleware authors.
.psgi files¶
A PSGI application is a code reference but it's not easy to pass code reference
via the command line or configuration files, so Plack uses a convention that
you need a file named "app.psgi" or similar, which would be loaded
(via perl's core function "do") to return the PSGI application code
reference.
# Hello.psgi
my $app = sub {
my $env = shift;
# ...
return [ $status, $headers, $body ];
};
If you use a web framework, chances are that they provide a helper utility to
automatically generate these ".psgi" files for you, such as:
# MyApp.psgi
use MyApp;
my $app = sub { MyApp->run_psgi(@_) };
It's important that the return value of ".psgi" file is the code
reference. See "eg/dot-psgi" directory for more examples of
".psgi" files.
plackup, Plack::Runner¶
plackup is a command line launcher to run PSGI applications from command line
using Plack::Loader to load PSGI backends. It can be used to run standalone
servers and FastCGI daemon processes. Other server backends like Apache2 needs
a separate configuration but ".psgi" application file can still be
the same.
If you want to write your own frontend that replaces, or adds functionalities to
plackup, take a look at the Plack::Runner module.
Plack::Middleware¶
PSGI middleware is a PSGI application that wraps an existing PSGI application
and plays both side of application and servers. From the servers the wrapped
code reference still looks like and behaves exactly the same as PSGI
applications.
Plack::Middleware gives you an easy way to wrap PSGI applications with a clean
API, and compatibility with Plack::Builder DSL.
Plack::Builder¶
Plack::Builder gives you a DSL that you can enable Middleware in
".psgi" files to wrap existent PSGI applications.
Plack::Request, Plack::Response¶
Plack::Request gives you a nice wrapper API around PSGI $env hash to get
headers, cookies and query parameters much like Apache::Request in mod_perl.
Plack::Response does the same to construct the response array reference.
Plack::Test¶
Plack::Test is a unified interface to test your PSGI application using standard
HTTP::Request and HTTP::Response pair with simple callbacks.
Plack::Test::Suite¶
Plack::Test::Suite is a test suite to test a new PSGI server backend.
CONTRIBUTING¶
Patches and Bug Fixes¶
Small patches and bug fixes can be either submitted via nopaste on IRC
<
irc://irc.perl.org/#plack> or the github issue tracker
<
http://github.com/miyagawa/Plack/issues>. Forking on github
<
http://github.com/miyagawa/Plack> is another good way if you intend to
make larger fixes.
See also <
http://contributing.appspot.com/plack> when you think this
document is terribly outdated.
Module Namespaces¶
Modules added to the Plack:: sub-namespaces should be reasonably generic
components which are useful as building blocks and not just simply using
Plack.
Middleware authors are free to use the Plack::Middleware:: namespace for their
middleware components. Middleware must be written in the pipeline style such
that they can chained together with other middleware components. The
Plack::Middleware:: modules in the core distribution are good examples of such
modules. It is recommended that you inherit from Plack::Middleware for these
types of modules.
Not all middleware components are wrappers, but instead are more like endpoints
in a middleware chain. These types of components should use the Plack::App::
namespace. Again, look in the core modules to see excellent examples of these
(Plack::App::File, Plack::App::Directory, etc.). It is recommended that you
inherit from Plack::Component for these types of modules.
DO NOT USE Plack:: namespace to build a new web application or a
framework. It's like naming your application under CGI:: namespace if it's
supposed to run on CGI and that is a really bad choice and would confuse
people badly.
AUTHOR¶
Tatsuhiko Miyagawa
COPYRIGHT¶
The following copyright notice applies to all the files provided in this
distribution, including binary files, unless explicitly noted otherwise.
Copyright 2009-2011 Tatsuhiko Miyagawa
CONTRIBUTORS¶
Yuval Kogman (nothingmuch)
Tokuhiro Matsuno (tokuhirom)
Kazuhiro Osawa (Yappo)
Kazuho Oku
Florian Ragwitz (rafl)
Chia-liang Kao (clkao)
Masahiro Honma (hiratara)
Daisuke Murase (typester)
John Beppu
Matt S Trout (mst)
Shawn M Moore (Sartak)
Stevan Little
Hans Dieter Pearcey (confound)
Tomas Doran (t0m)
mala
Mark Stosberg
Aaron Trevena
SEE ALSO¶
The PSGI specification upon which Plack is based.
<
http://plackperl.org/>
The Plack wiki: <
https://github.com/miyagawa/Plack/wiki>
The Plack FAQ: <
https://github.com/miyagawa/Plack/wiki/Faq>
LICENSE¶
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.