Rack

Rack Scott Leberknight

HTTP make request, get response

Request a hash containing the environment (headers, params, input stream)

Response status, headers, body

Simplest Rack App..

class Hello status def call(env) headers [ 200, { "Content-Type" => "text/plain" }, [ "Hello!", "Having fun yet?" ] ] end end body

Middleware Order Matters !

middlewares call() each other... and act like chain of response ﬁlters... ...so the order you use them matters!

init with app class Reverse def initialize(app) first, Call the app @app = app end def call(env) status, headers, body = @app.call(env) [status, headers, body.map { |b| b.reverse }] end end then, do your stuff

use Rack::ContentLength use RackExamples::Paragraphizer use RackExamples::Upcase use use RackExamples::Downcase RackExamples::Reverse Is output upper or app = lambda { |env| [ lower case? 200, { 'Content-Type' => 'text/html' }, ["Dammit, I'm mad!", "Was it a rat I saw?", "Madam, I'm Adam"] ] } run app 11

use Rack::ContentLength use RackExamples::Paragraphizer use RackExamples::Downcase use RackExamples::Upcase use RackExamples::Reverse How about now? app = lambda { |env| [ 200, { 'Content-Type' => 'text/html' }, ["Dammit, I'm mad!", "Was it a rat I saw?", "Madam, I'm Adam"] ] } run app 12

"Off t he Shelf"

Rack::ShowExceptions Rack::MailExceptions Rack::CommonLogger Rack::ContentLength Rack::JSON ActionController::StringCoercion Rack::ETag Rack::Deflater ...and lots more

Baked into Ra ils

$ rake middleware (in /Users/sleberkn/Projects/my-niclabs) use Rack::Lock use ActionController::Failsafe use ActionController::Session::CookieStore, #<Proc:0x00000001017acf18@(eval):8> use ActionController::ParamsParser use Rack::MethodOverride use Rack::Head use ActionController::StringCoercion use Rack::Deflater use Sass::Plugin::Rack use ActiveRecord::ConnectionAdapters::ConnectionManagement use ActiveRecord::QueryCache run ActionController::Dispatcher.new

Summary

References

http://lmgtfy.com/?q=ruby+rack http://www.letmebingthatforyou.com/?q=ruby+rack

Image credits Shelf thedesignblog.org/entry/odersoding-storage-system-doubles-as-a-room-divider/ Cool newgeography.com Baking haileythebaketress.blogspot.com Json nearinﬁnity.com

scott.leberknight@nearinfinity.com www.nearinfinity.com/blogs/ twitter: sleberknight

Rack

by Scott Leberknight on Oct 21, 2010

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