rack

8 minutes on

Rackbased on a presentation byDan Webb (dan@danwebb.net)@danwronghttp://slidesha.re/dan_on_rack

A Convention

If you have a Ruby object...

that has a call method which takes one argument...

app.call(env)

and that method returns an array with 3 elements...

[200, { 'Content-Type' => 'text/plain' }, 'Hello World!']

then you can connect it to any web server that supports Rack

require 'thin' Rack::Handler::Thin.run(app, :Port => 4000)

and you've got yourself a web application

That's it.

For Example...

app = Proc.new do |env| [200, { 'Content-Type' => 'text/plain' }, 'Hello World!'] end

require 'rubygems' require 'thin'Rack::Handler::Thin.run(app, :Port => 4000)

class HelloWorld def initialize(name) @name = name end

def call(env) [200, { 'Content-Type' => 'text/plain' }, "Hello #{@name}!"] end end

require 'rubygems' require 'rack'Rack::Handler::Mongrel.run(HelloWorld.new("Dan"), :Port => 4000)

def call(env)

{ "SERVER_NAME"=>"localhost", "HTTP_ACCEPT_ENCODING"=>"gzip,deflate", "HTTP_USER_AGENT"=>"Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en- GB; rv:1.9.0.4) Gecko/2008102920 Firefox/3.0.4", "PATH_INFO"=>"/", "SCRIPT_NAME"=>"", "SERVER_PROTOCOL"=>"HTTP/1.1", "HTTP_ACCEPT_LANGUAGE"=>"en-gb,en;q=0.5", "HTTP_HOST"=>"localhost:4000", "REMOTE_ADDR"=>"127.0.0.1", "HTTP_KEEP_ALIVE"=>"300", "REQUEST_PATH"=>"/", "SERVER_SOFTWARE"=>"thin 0.8.2 codename Double Margarita", "HTTP_ACCEPT_CHARSET"=>"ISO-8859-1,utf-8;q=0.7,*;q=0.7", "HTTP_VERSION"=>"HTTP/1.1", "REQUEST_URI"=>"/", "SERVER_PORT"=>"4000", "QUERY_STRING"=>"", "GATEWAY_INTERFACE"=>"CGI/1.2", "HTTP_ACCEPT"=>"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "HTTP_CONNECTION"=>"keep-alive", "REQUEST_METHOD"=>"GET"}

[200, { 'Content-Type' => 'text/plain' }, "Hello #{@name}!"]

Status Code

[200, { 'Content-Type' => 'text/plain' }, "Hello #{@name}!"]

HTTP Headers

[200, { 'Content-Type' => 'text/plain' }, "Hello #{@name}!"]

Response Body

Response body can be any object that respond_to?(:each)

file = File.new('myfile.xml') [200, { 'Content-Type' => 'application/xml' }, file]

For Example...

class StreamingFile def initialize(file) @file = file end

def length File.size(@file) end

def last_modified File.mtime(@file).rfc822 end

def each File.open(@file, "rb") do |file| while part = file.read(8192) yield part end File.delete(@file) end end

[200, { 'Content-Type' => 'audio/mp3', 'Content-Length' => file.length.to_s}, file]

Duck Typing!

• Streaming

• Clean up after response sent

• Complex responses

• Loads more...

Why?

Common interface

• Passenger

• Mongrel

• CGI

• SCGI

• FastCGI

• Thin

• Ebb

• Fuzed

• Webrick

• Litespeed

Write once, serve however...

Convienient way to write

micro apps

There's More...

• The Rack Gem

• Middleware

• Rack and Passenger

• rackup

rack.rubyforge.org

What about Rails?

Rails is a Rack Application

config.ru

# This file is used by Rack-based servers to start the application.

require ::File.expand_path('../config/environment', __FILE__)run MyApp::Application

routes.rb

# You can call any Rack app from a route

match "/foo" => MySinatraApp

match "/bar" => MyMiddleware.new(OtherApp)

Questions?

Original Presentation by Dan Webb, @danwrongModified with Rails examples by Sarah Allen

@ultrasaurus, Blazing Cloud