1. Plack
Superglue for Perl Web Frameworks
Tatsuhiko Miyagawa
YAPC::NA 2010

2. Tatsuhiko Miyagawa
• Lives in San Francisco
• Software Engineer @ Six Apart
• http://search.cpan.org/~miyagawa/
• @miyagawa
• http://bulknews.typepad.com/

3. Web Applications

4. Hello World

5. #!/usr/bin/perl
use strict;
print “Content-Type: text/plainrnrn”;
print “Hello World”;

6. use FCGI;
my $req = FCGI::Request();
while ($req->Accept >= 0) {
print “Content-Type: text/plainrnrn”;
print “Hello World”;
}

7. package HelloWorld;
use strict;
use Apache::RequestRec;
use Apache::RequestIO;
use Apache::Const -compile => qw(OK);
sub handler {
my $r = shift;
$r->content_type(‘text/plain’);
$r->print(“Hello World”);
return Apache::Const::OK;
}
1;

8. package HelloWorld;
use base qw(HTTP::Server::Simple::CGI);
sub handle_request {
my($self, $cgi) = @_;
print “HTTP/1.0 200 OKrn”;
print “Content-Type: text/plainrnrn”;
print “Hello World”;
}
1;

9. All similar
but slightly different

10. There is (was)
one common way
to do all of this.

11. #!/usr/bin/perl
use CGI;
my $q = CGI->new;
print $q->header(‘text/plain’);
print “Hello World”;

12. Happens to work on:
CGI, FastCGI, mod_perl
(HTTP::Server::Simple::CGI)

13. CGI.pm?
meh

14. Frameworks
to the rescue!

15. Maypole Mason Mojo Sledge Catalyst Spoon
PageKit AxKit Egg Gantry Continuity Solstice
Mojolicious Tripletail Konstrukt Reaction Jifty
Cyclone3 WebGUI OpenInteract Squatting
Dancer CGI::Application Nanoa Ark Angelos
Noe Schenker Tatsumaki Amon
Apache2::WebApp Web::Simple Apache2::REST
SweetPea Hydrant Titanium

16. MANY
web frameworks

17. CGI.pm
Jifty, CGI::Application, Spoon
mod_perl centric
Mason, Sledge, PageKit, WebGUI
Adapters
Catalyst, Maypole, Squatting

18. That was 2008.

19. Steal great idea
from Python/Ruby

20. WSGI (Python)
Rack (Ruby)

21. WSGI (PEP-333)

23. # WSGI
def hello(environ, start_response):
start_response(“200 OK”, [
(‘Content-Type’, ‘text/plain’)
])
return [“Hello World”]

24. WSGI
• Django • mod_wsgi
• Bottle • Paste
• CherryPy • gunicorn
• Tornado • uWSGI
• Pylons • wsgiref
• Flask • Google AppEngine

25. Django Bottle Flask Tornado
WSGI middleware
WSGI
wsgi handlers
Apache lighttpd nginx mod_wsgi GAE

26. Rack

28. # Rack
class Hello
def call(env)
return [
200,
{ “Content-Type” => ”text/plain” },
[“Hello World”]
]
end
end

29. Rack
• Rails • Unicorn
• Merb • Thin
• Sinatra • Mongrel
• Camping • Rainbows!
• Ramaze • Phusion Passenger
• etc. • Heroku

30. Rails Merb Sinatra Ramaze
Rack middleware
Rack
Rack handlers
Apache lighttpd Thin Unicorn Mongrel

31. PSGI
Perl Web Server Gateway Interface

32. Interface

33. # WSGI
def hello(environ, start_response):
start_response(“200 OK”, [
(‘Content-Type’, ‘text/plain’)
])
return [“Hello World”]

34. # Rack
class Hello
def call(env)
return [
200,
{ “Content-Type” => ”text/plain” },
[“Hello World”]
]
end
end

35. # PSGI
my $app = sub {
my $env = shift;
return [
200,
[ ‘Content-Type’, ‘text/plain’ ],
[ ‘Hello World’ ],
];
};

36. PSGI application
code reference
$app = sub {...};

37. my $app = sub {
my $env = shift;
return [ $status, $header, $body ];
};

38. environment hash
$env: CGI-like env variables
+ psgi.input, psgi.errors etc.

39. my $app = sub {
my $env = shift;
return [ $status, $header, $body ];
};

40. Response
array ref with three elements
status code, headers (array ref)
and body (IO-like or array ref)

41. my $app = sub {
my $env = shift;
return [ $status, $header, $body ];
};

42. $body
IO::Handle-like
getline() and close()

43. That’s it.

44. # PSGI
my $app = sub {
my $env = shift;
return [
200,
[ ‘Content-Type’, ‘text/plain’ ],
[ ‘Hello World’ ],
];
};

45. Now you’ve got
a PSGI application.

46. PSGI makes it
so simple to:

47. Write a new Perl
web app & framework

48. Write a new Perl
web server

49. Catalyst CGI::App Jifty Tatsumaki
Plack::Middleware
PSGI
Plack::Handler::* (CGI, FCGI, Apache)
Apache lighttpd HTTP::Server::PSGI mod_psgi Perlbal

50. PSGI adaptation

51. Maypole Mason Mojo Sledge Catalyst Spoon PageKit
AxKit Egg Gantry Continuity Solstice Mojolicious
Tripletail Konstrukt Reaction Jifty Cyclone3 WebGUI
OpenInteract Squatting Dancer CGI::Application
Nanoa Ark Angelos Noe Schenker Tatsumaki Amon
Apache2::WebApp Web::Simple Apache2::REST
SweetPea Hydrant Titanium

52. Maypole Mason Mojo Sledge Catalyst Spoon PageKit
AxKit Egg Gantry Continuity Solstice Mojolicious
Tripletail Konstrukt Reaction Jifty Cyclone3 WebGUI
OpenInteract Squatting Dancer CGI::Application
Nanoa Ark Angelos Noe Schenker Tatsumaki Amon
Apache2::WebApp Web::Simple Apache2::REST
SweetPea Hydrant Titanium

53. Applications
Movable Type 6, WebGUI 8

54. # Catalyst
use MyApp;
MyApp->setup_engine(‘PSGI’);
my $app = sub { MyApp->run(@_) };
# $app is a PSGI app!

55. # Jifty
use MyPonyApp;
my $app = MyPonyApp->psgi_app;
# $app is a PSGI app!

56. # Dancer
use Dancer;
get ‘/’ => sub {
“Hello World”;
};
dance; # returns a PSGI app!

57. # Mojolicious::Lite
use Mojolicious::Lite;
get ‘/:name’ => sub {
my $self = shift;
$self->render_text(‘Hello!’);
};
shagadelic; # returns PSGI app

58. # Web::Simple
use Web::Simple ‘MyApp’;
package MyApp;
dispatch {
sub(GET) {
[ 200, [...], [ ‘Hello’ ] ];
}
};
my $app = MyApp->as_psgi;
# $app is a PSGI app!

59. Plack
“PSGI toolkit”

60. HTTP::Server::PSGI
Reference PSGI web server
bundled in Plack

61. Plackup
Runs PSGI app instantly from CLI
(inspired by rackup)

62. > plackup app.psgi

63. Plack::Handler
Connects PSGI apps to Web servers
CGI, FastCGI, Apache, SCGI

64. PSGI Web Servers

65. Starman
UNIX Preforking HTTP servers (like Unicorn.rb)
HTTP/1.1 chunk + keep-alives / Very Fast

66. Starlet
Simpler UNIX HTTP/1.0 Server
Best used with Server::Starter and nginx/lighttpd

67. Twiggy
Non-blocking web server (like Thin.rb)
based on AnyEvent framework

68. Corona
Coroutine for each connection based on Coro.pm

69. HTTP::Server::Simple::PSGI
Zero-deps other than HTTP::Server::Simple
Best for embedding PSGI applications

70. uWSGI
http://projects.unbit.it/uwsgi/

71. Perlbal plugin
http://github.com/miyagawa/Perlbal-Plugin-PSGI

72. nginx embedded perl
http://github.com/yappo/nginx-psgi-patchs

73. mod_psgi
http://github.com/spiritloose/mod_psgi

74. evpsgi
http://github.com/sekimura/evpsgi

75. Feersum
http://github.com/stash/Feersum

76. Catalyst CGI::App Jifty Tatsumaki
Plack::Middleware
PSGI
Plack::Handler::* (CGI, FCGI, Apache)
Apache lighttpd HTTP::Server::PSGI mod_psgi Perlbal
Starman Twiggy uWSGI Corona evpsgi

77. Middleware

79. PSGI Middleware
Wraps a PSGI application
to add pre/post processing

80. my $app = sub {
my $env = shift;
return [ $status, $header, $body ];
};
my $mw = sub {
my $env = shift;
# do something with $env
my $res = $app->($env);
# do something with $res;
return $res;
};

81. PSGI Middleware
coderef -> coderef
Higher-order functions

82. Middleware
Debug, Session, Logger, Runtime, Static, Lint,
AccessLog, ConditionalGET, ErrorDocument,
StackTrace, Auth::Basic, Auth::Digest, ReverseProxy,
Refresh, Auth::OAuth, Hippie, Throttle

83. Plack::Middleware
reusable and extensible
Middleware framework
Plack::Builder DSL in .psgi

84. my $app = sub {
return [ $status, $header, $body ];
};
use Plack::Builder;
builder {
enable “Static”, root => “/htdocs”,
path => qr!^/static/!;
enable “Deflater”; # gzip/deflate
$app;
}

85. plackup compatible
plackup -e ‘enable “Foo”;’ app.psgi

86. Middleware
Write once, run in every framework

87. DEMO

88. Plack::App::URLMap
Multiplex multiple apps
Integrated with Builder DSL

89. use CatApp;
use CGIApp;
my $c1 = sub { CatApp->run };
my $c2 = sub { CGIApp->run_psgi };
use Plack::Builder;
builder {
mount “/cat” => $c1;
mount “/cgi-app” => builder {
enable “StackTrace”;
$c2;
};
}

90. CGI::PSGI
Easy migration from CGI.pm

91. CGI::Emulate::PSGI
CGI::Compile
Easiest migration from CGI scripts (like Registry)

92. Plack::Request
like libapreq (Apache::Request)
wrapper APIs for middleware developers

93. Plack::Test
Unified interface to write tests
with Mock HTTP and Live HTTP

94. use Plack::Test;
use HTTP::Request::Common;
my $app = sub {
my $env = shift;
return [ $status, $header, $body ];
};
test_psgi app => $app, client => sub {
my $cb = shift;
my $req = GET “http://localhost/foo”;
my $res = $cb->($req);
# test $res;
};

95. use Plack::Test;
use HTTP::Request::Common;
$Plack::Test::Impl = “Server”;
my $app = sub {
my $env = shift;
return [ $status, $header, $body ];
};
test_psgi app => $app, client => sub {
my $cb = shift;
my $req = GET “http://localhost/foo”;
my $res = $cb->($req);
# test $res;
};

96. Plack::App::*
ready-to-use applications

97. Plack::App::Directory
Static content file server

98. Plack::App::Proxy
(non-blocking) proxy server
Can be used as reverse proxy as well

99. Plack::App::CGIBin
mount /cgi-bin as PSGI applications

100. Plack::App::FCGIDispatcher
Connect to FCGI daemon
(even in Ruby, Python, C)

101. Plack::App::JSP
Runs JavaScript PSGI apps :)

102. Real World
Plack/PSGI

104. You should join!

105. > cpanm Plack
> cpanm Task::Plack

106. Haven’t used cpanm?
Come to Nationwide (Cartoon 2)
Wednesday 9:30

107. Cloud?
(Heroku, GAE)

108. Sunaba
http://sunaba.plackperl.org/

110. Runs on dankogai’s
Sandbox

111. You can even try:
system(“rm -fr /”);
while (1) { }

112. Summary
• PSGI is an interface, Plack is the code.
• We have many (pretty fast) PSGI servers.
• We have adapters and tools for most web
frameworks.
• Use it!

113. Remember:
Plack is < 1y old

114. Lots of (exciting)
things going on.

115. http://blog.plackperl.org/

116. http://github.com/miyagawa/Plack
http://plackperl.org/
irc://irc.perl.org/#plack

117. Questions?