Rails Metal,
Rack, and Sinatra
Adam Wiggins
Railsconf 2009

Show of hands, how
many of you...

metal

Show of hands, how
many of you...

“The gateway drug”

“The gateway drug”*
* it’s a myth, but makes good analogy

Rails Metal is a
gateway

Rails Metal is a
gateway to the
world of Rack

What can you do with
Metal?

Replace selected
URLs for a speed
boost

Example: auction site

Example: auction site

Example: auction site
on

Majority of traffic goes to:
GET /auctions/id.xml

app/controller/auctions_controller.rb

app/controller/auctions_controller.rb
class AuctionsController < ApplicationController
def show
@auction = Auction.find(params[:id])
respond_to do |format|
format.html
format.xml { render :xml => @auction }
end
end
end

app/metal/auctions_api.rb

app/metal/auctions_api.rb
class AuctionsApi
def self.call(env)
# implementation goes here
end
end

app/metal/auctions_api.rb
class AuctionsApi
def self.call(env)
url_pattern = %r{/auctions/(\\d+).xml}
if m = env['PATH_INFO'].match(url_pattern)
# render the auction api
else
# pass (do nothing)
end
end
end

app/metal/auctions_api.rb
class AuctionsApi
def self.call(env)
url_pattern = %r{/auctions/(\\d+).xml}
if m = env['PATH_INFO'].match(url_pattern)
auction = Auction.find(m[1])
[ 200, {\"Content-Type\" => \"text/xml\"},
auction.to_xml ]
else
[ 404, {}, '' ]
end
end
end

[
200,
{\"Content-Type\"=>\"text/plain\"},
\"Hello, Rack!\"
]

[
200,
{\"Content-Type\"=>\"text/plain\"},
\"Hello, Rack!\"
]

http://www.slideshare.net/adamwiggins/
ruby-isnt-just-about-rails-presentation

An explosion of Ruby
projects in the past 2
years

Tests/Specs
Web Layer
Test::Unit
ActionController
RSpec
Merb
Shoulda
Sinatra
ORM Templating
ActiveRecord Erb
DataMapper Haml
Sequel Erubis
Web Server
HTTP Client
Mongrel
ActiveResource
Thin
RestClient
Ebb
HTTParty

Tests/Specs
Web Layer
Test::Unit
ActionController
ORM Templating
ActiveRecord Erb
Web Server
HTTP Client
Mongrel
ActiveResource

Tests/Specs
Web Layer
Test::Unit
ActionController
ORM Templating
ActiveRecord Erb
Web Server
HTTP Client
Mongrel
ActiveResource

Tests/Specs
Web Layer
Test::Unit
ActionController
RSpec
Merb
Shoulda
Sinatra
ORM Templating
ActiveRecord Erb
DataMapper Haml
Sequel Erubis
Web Server
HTTP Client
Mongrel
ActiveResource
Thin
RestClient
Ebb
HTTParty

Tests/Specs
Web Layer
Test::Unit
ActionController
RSpec
Merb
Shoulda
Sinatra
ORM Templating
ActiveRecord Erb
DataMapper Haml
Sequel Erubis
Web Server
HTTP Client
Mongrel
ActiveResource
Thin
RestClient
Ebb
HTTParty

Tests/Specs
Web Layer
Test::Unit
ActionController
RSpec
Merb
Shoulda
Sinatra
ORM Templating
ActiveRecord Erb
DataMapper Haml
Sequel Erubis
Web Server
HTTP Client
Mongrel
ActiveResource
Thin
RestClient
Ebb
HTTParty

The world of Rack is
now within reach from
Rails

Sinatra
The classy
microframework for Ruby
http://sinatrarb.com

require 'rubygems'
require 'sinatra'
get '/hello' do
\"Hello, whirled\"
end

$ ruby hello.rb
== Sinatra/0.9.1.1 has taken the stage
>> Thin web server (v1.0.0)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:4567

$ ruby hello.rb
== Sinatra/0.9.1.1 has taken the stage
>> Thin web server (v1.0.0)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:4567
$ curl http://localhost:4567/hello
Hello, whirled

A minimalist paradise

require 'rubygems'
require 'sinatra'
require 'lib/article'
post '/articles' do
article = Article.create! params
redirect \"/articles/#{article.id}\"
end
get '/articles/:id' do
@article = Article.find(params[:id])
erb :article
end

Sinatra in your Rails
app?

Replace selected
URLs for a speed
boost

Replace selected
URLs for a speed
boost

Replace selected
URLs with Sinatra

app/metal/articles.rb

app/metal/articles.rb
require 'sinatra/base'
class Articles < Sinatra::Base
post '/articles' do
article = Article.create! params
redirect \"/articles/#{article.id}\"
end
get '/articles/:id' do
@article = Article.find(params[:id])
erb :article
end
end

Back to the auction
example

Back to the auction
example

ActionController
class AuctionsController < ApplicationController
def show
@auction = Auction.find(params[:id])
respond_to do |format|
format.html
format.xml { render :xml => @auction }
end
end
end

Pure Rack
class AuctionsApi
def self.call(env)
url_pattern = /^\\/auctions\\/(\\d+).xml$/
if m = env['PATH_INFO'].match(url_pattern)
auction = Auction.find(m[1])
[ 200, {\"Content-Type\" => \"text/xml\"},
auction.to_xml ]
else
[ 404, {}, '' ]
end
end
end

Sinatra
get '/auctions/:id.xml'
Auction.find(params[:id]).to_xml
end

Sinatra
get '/auctions/:id.xml'
Auction.find(params[:id]).to_xml
end
Now that’s what I call
minimalist.

The End.
http://railscasts.com/episodes/150-rails-metal
http://rack.rubyforge.org
http://sinatrarb.com
http://adam.blog.heroku.com
Adam Wiggins
Railsconf 2009