Intro to PSGI and Plack
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PSGI is a Perl port of Python's WSGI and Ruby's Rack that defines a common interface between web servers and frameworks. Plack provides reference implementations of PSGI servers as well as middleware and utilities. This allows frameworks to run on many servers like standalone, FastCGI, and Apache using a common PSGI application interface. Plack is fast, supports many frameworks through adapters, and provides tools like Plackup and middleware to help build and test PSGI applications.
![Mo[ou]se everywhere
Mouse is light but still overspec for some env.](https://image.slidesharecdn.com/psgi-plack-091007171818-phpapp01/85/Intro-to-PSGI-and-Plack-26-320.jpg)
![my $app = sub {
my $env = shift;
# ...
return [ $status, $header, $body ];
};](https://image.slidesharecdn.com/psgi-plack-091007171818-phpapp01/85/Intro-to-PSGI-and-Plack-39-320.jpg)
![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;
};](https://image.slidesharecdn.com/psgi-plack-091007171818-phpapp01/85/Intro-to-PSGI-and-Plack-58-320.jpg)
![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;
};](https://image.slidesharecdn.com/psgi-plack-091007171818-phpapp01/85/Intro-to-PSGI-and-Plack-64-320.jpg)
![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;
};](https://image.slidesharecdn.com/psgi-plack-091007171818-phpapp01/85/Intro-to-PSGI-and-Plack-65-320.jpg)
![use IO::Handle::Util qw(io_from_getline);
my $app = sub {
my $env = shift;
my $io = io_from_getline sub {
return $chunk; # undef when done
};
return [ $status, $header, $io ];
};](https://image.slidesharecdn.com/psgi-plack-091007171818-phpapp01/85/Intro-to-PSGI-and-Plack-67-320.jpg)
![use IO::Writer; # TBD: API might change
use AnyEvent::Timer;
my $app = sub {
my $env = shift;
my $io = writer {
my $h = shift;
my $t; $t = AE::timer 0, 1, sub {
$t;
$h->push_write($stuff);
};
};
return [ $status, $header, $io ];
};](https://image.slidesharecdn.com/psgi-plack-091007171818-phpapp01/85/Intro-to-PSGI-and-Plack-68-320.jpg)
Intro to PSGI and Plack
- 1. PSGI and Plack Tatsuhiko Miyagawa
- 2. PSGI Perl Web Server Gateway Interface
- 3. Plack PSGI ref. implementations Utilities
- 4. A Perl port of: Pythons WSGI and Rubys Rack (will talk about them later)
- 5. WHY
- 7. Maypole Mason Mojo Sledge Catalyst Spoon PageKit AxKit Egg Gantry Continuity Solstice Mojolicious Tripletail Konstrukt Re鍖ection Jifty Cyclone3 OpenInteract Squatting Dancer CGI::Application Nanoa Ark Angelos Noe Schenker
- 8. Most of them run on mod_perl and CGI
- 9. Some run on FCGI
- 11. Very few supports non-blocking
- 12. Because:
- 13. No common server environment layers
- 14. CGI.pm
- 15. Runs 鍖ne on: CGI, FastCGI, mod_perl (1 & 2) Standalone (with HTTP::Server::Simple)
- 16. CGI.pm = LCD Its also Perl core
- 17. > grep (CGI.pm|ENV) lib/MT/App.pm if ( my $path_info = $ENV{PATH_INFO} ) { # de鍖ned which interferes with CGI.pm determining the delete $ENV{PATH_INFO}; # CGI.pm has this terrible 鍖aw in that if a POST is in effect, my $query_string = $ENV{'QUERY_STRING'} if de鍖ned $ENV{'QUERY_STRING'}; $query_string ||= $ENV{'REDIRECT_QUERY_STRING'} if de鍖ned $ENV{'REDIRECT_QUERY_STRING'}; my $len = $ENV{CONTENT_LENGTH} || 0; return $ENV{ 'HTTP_' . $key }; $app->{request_method} = $ENV{REQUEST_METHOD} || ''; ## Older versions of CGI.pm didn't have an 'upload' method. if ( my $host = $ENV{HTTP_HOST} ) { : $ENV{REMOTE_ADDR}); $cwd = $ENV{DOCUMENT_ROOT} || $app->mt_dir;
- 18. Not cool.
- 19. Catalyst The most popular framework as of today
- 20. Catalyst::Engine::* Server abstractions. Well supported Apache, FCGI and Standalone
- 21. Problems: Duplicated efforts No fair performance evaluations
- 22. Catalyst::Engine for the rest of us
- 23. = HTTP::Engine
- 24. HTTP::Engine Lots of adapters (FCGI, Apache2, POE) Clean Request/Response API Written by Yappo, tokuhirom and others
- 25. Problem
- 26. Mo[ou]se everywhere Mouse is light but still overspec for some env.
- 27. Monolithic All implementations share HTTP::Engine roles and builders, which is sometimes hard to adapt and has less place for optimizations.
- 28. APIs everywhere Most frameworks have their request/response API Sometimes there are gaps. Annoying to write bridges and wrappers
- 29. Solution
- 30. Steal good stuff from Python/Ruby
- 31. WSGI (Python) Rack
- 32. WSGI (PEP-333) mod_wsgi, Tornado, Paste, GAE Django, CherryPy, Pylons
- 33. Rack Passenger, Thin, rack, Heroku Rails, Merb, Sinatra
- 34. Split HTTP::Engine into three parts
- 35. Interface Implementations Utilities
- 36. PSGI (interface) Plack::Server (implementations) Plack::* (utilities)
- 37. PSGI
- 38. Interface
- 39. my $app = sub { my $env = shift; # ... return [ $status, $header, $body ]; };
- 40. PSGI application code reference $app = sub {...};
- 41. environment hash $env: CGI-like env variables + psgi.input, psgi.errors etc.
- 42. Why a big hash? Easy to adapt if you have CGI adapter Also follows what WSGI/Rack do
- 43. Response array ref with three elements status code, headers (array ref) and body (IO-like or array ref)
- 44. $body IO::Handle-like getline() and close()
- 45. IO::Handle-like We really envy Python/Ruby for built-in iterators (Perls 鍖lehandle is also an object, but it really sucks)
- 46. Frameworks Write an adapter to return PSGI application code ref.
- 47. Servers Set up $env, run the app and emits response out of $res
- 48. Middleware Plays both side Application wrapper
- 49. Plack
- 50. Plack::Server reference server implementations Standalone, FCGI, Apache2, CGI Standalone, Prefork, AnyEvent, Coro
- 51. Very fast 5000 QPS on standalone 15000 QPS with prefork :)
- 52. Framework Adapters CGI::Application, Catalyst, Maypole Mason, Squatting, Mojo, HTTP::Engine etc.
- 54. Utilities
- 55. Plackup Run PSGI app instantly from CLI (inspired by rackup)
- 56. DEMO
- 57. Middlewares
- 58. 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; };
- 59. Middlewares Static, AccessLog, ConditionalGET ErrorDocument, StackTrace etc.
- 60. Plack::Middleware reusable and extensible Middleware framework Plack::Builder DSL in .psgi
- 61. CGI::PSGI Easy migration from CGI.pm
- 62. Plack::Request like libapreq (Apache::Request) wrapper APIs for framework developers
- 63. Plack::Test Uni鍖ed interface to write tests with Mock HTTP and Live HTTP
- 64. 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; };
- 65. 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; };
- 66. Streaming event loop / long-poll
- 67. use IO::Handle::Util qw(io_from_getline); my $app = sub { my $env = shift; my $io = io_from_getline sub { return $chunk; # undef when done }; return [ $status, $header, $io ]; };
- 68. use IO::Writer; # TBD: API might change use AnyEvent::Timer; my $app = sub { my $env = shift; my $io = writer { my $h = shift; my $t; $t = AE::timer 0, 1, sub { $t; $h->push_write($stuff); }; }; return [ $status, $header, $io ]; };
- 69. Other Servers
- 70. nginx embedded perl http://github.com/yappo/nginx-psgi-patchs
- 73. Cloud
- 74. WSGI (PEP-333) mod_wsgi, Tornado, Paste, GAE Django, CherryPy, Pylons
- 75. Rack Passenger, Thin, rack, Heroku Rails, Merb, Sinatra
- 76. What if GAE Perl comes with PSGI ...
- 77. Summary PSGI is an interface, Plack is the code. We have many (pretty fast) servers. We have adapters and tools for most web frameworks. Use it!
- 78. http://github.com/miyagawa/Plack http://plackperl.org/
- 79. Questions?