Rack in Rails 3 <http://twitter.com/rtomayko> Ryan Tomayko - - PowerPoint PPT Presentation

Rack in Rails 3

Ryan Tomayko

• Rack (Core Team)
• Rack::Contrib (Maintainer)
• Sinatra (Committer)
• Rack::Cache (Maintainer)
• Shotgun (Maintainer)

<http://twitter.com/rtomayko>

GitHub

"Get a better logo, guys." -- Tim Bray

The Rack SPEC

<http://rack.rubyforge.org/doc/SPEC.html>

• "Just" a document.
• Conventions for expressing HTTP in Ruby.
• Interface, Contract, Agreement, Protocol.
• Based on Python's WSGI.
• Fits on a single slide.

Expressing HTTP in Ruby

GET
/hello
HTTP/1.1 Host:
localhost:9292 Connection:
keep‐alive User‐Agent:
Mozilla/5.0
(Macinto... Accept:
application/xml,applicati... Accept‐Encoding:
gzip,deflate,sdch Accept‐Language:
en‐US,en;q=0.8 Accept‐Charset:
UTF‐8,*;q=0.5 Cache‐Control:
max‐age=0 Cookie:
foo=bar

HTTP Request

GET
/hello
HTTP/1.1 Host:
localhost:9292 Connection:
keep‐alive User‐Agent:
Mozilla/5.0
(Macinto... Accept:
application/xml,applicati... Accept‐Encoding:
gzip,deflate,sdch Accept‐Language:
en‐US,en;q=0.8 Accept‐Charset:
UTF‐8,*;q=0.5 Cache‐Control:
max‐age=0 Cookie:
foo=bar

HTTP Request

{"REQUEST_METHOD"=>"GET", 
"PATH_INFO"=>"/hello", 
"SCRIPT_NAME"=>"", 
"SERVER_NAME"=>"localhost", 
"SERVER_PORT"=>"9292", 
"REMOTE_ADDR"=>"127.0.0.1", 
"QUERY_STRING"=>"", 
"HTTP_HOST"=>"localhost:9292", 
"HTTP_CONNECTION"=>"keep‐alive", 
"HTTP_USER_AGENT"=>"Mozilla/5.0
(...", 
"HTTP_ACCEPT"=>"application/xml,a...", 
"HTTP_ACCEPT_ENCODING"=>"gzip,def...", 
"HTTP_ACCEPT_LANGUAGE"=>"en‐US,en...", 
"HTTP_ACCEPT_CHARSET"=>"UTF‐8,*;q=0.5", 
"HTTP_CACHE_CONTROL"=>"max‐age=0", 
"HTTP_COOKIE"=>"foo=bar", 
"rack.url_scheme"=>"http", 
"rack.input"=>#<StringIO:0x10841ec>, 
"rack.errors"=>#<IO:0x3a8d4c>, 
"rack.version"=>[1,
1], 
"rack.run_once"=>false, 
"rack.multithread"=>true, 
"rack.multiprocess"=>false}

Rack "env" Hash

HTTP/1.1
200
OK Connection:
close Date:
Tue,
16
Feb
2010
23:49:18
GMT Content‐Type:
text/plain Content‐Length:
11 Cache‐Control:
max‐age=60 Hello
World

HTTP Response

HTTP/1.1
200
OK Connection:
close Date:
Tue,
16
Feb
2010
23:49:18
GMT Content‐Type:
text/plain Content‐Length:
11 Cache‐Control:
max‐age=60 Hello
World

HTTP Response

[ 

200, 

{'Content‐Type'


=>
'text/plain', 


'Content‐Length'
=>
'11', 


'Cache‐Control'

=>
'max‐age=60'}, 

["Hello
World"] ]

Rack Response

HTTP/1.1
200
OK Connection:
close Date:
Tue,
16
Feb
2010
23:49:18
GMT Content‐Type:
text/plain Content‐Length:
11 Cache‐Control:
max‐age=60 Hello
World

HTTP Response

[ 

200, 

{'Content‐Type'


=>
'text/plain', 


'Content‐Length'
=>
'11', 


'Cache‐Control'

=>
'max‐age=60'}, 

["Hello
World"] ]

Rack Response

[ 

200, 

{'Content‐Type '


=>
'text/plain', 


'Content‐Length '
=>
File.size('hello.txt').to_s , 


'Cache‐Control '

=>
'max‐age=60'}, 

File.open('hello.txt',
'rb') ]

OR

A Rack application is an Ruby object (not a class) that responds to call. It takes exactly one argument, the environment and returns an Array of exactly three values: the status, the headers, and the body.

class
HelloWorldApp 

def
call(env) 



[200, 




{'Content‐Type'
=>
'text/plain'}, 




["Hello
World"]] 

end end 
 app
=
HelloWorldApp.new

class
HelloWorldApp 

def
call(env) 



[200, 




{'Content‐Type'
=>
'text/plain'}, 




["Hello
World"]] 

end end 
 app
=
HelloWorldApp.new app
=
lambda
{
|env| 

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

OR

We haven't used any Rack APIs yet.

Interoperability

WEBrick CGI FastCGI Mongrel Thin Passenger Unicorn Heroku Rails Sinatra Merb Ramaze Camping Coset Rango Just Rack

Servers Frameworks

Rack SPEC

Interoperability

WEBrick CGI FastCGI Mongrel Thin Passenger Unicorn Heroku Rails Sinatra Merb Ramaze Camping Coset Rango Just Rack

Servers Frameworks

Rack SPEC

Architecture of Intermediaries

HTTP Intermediaries

Company Proxy

Alice Bob Carol

HTTP HTTP HTTP HTTP HTTP

Auth + Logging Compression

Regional Proxy

Load Balancing

App 1 App 2

HTTP HTTP HTTP HTTP HTTP HTTP

separate process inside example.com firewall

HTTP Intermediaries

Company Proxy

Alice Bob Carol

HTTP HTTP HTTP HTTP HTTP

Auth + Logging Compression

Regional Proxy

Load Balancing

App 1 App 2

HTTP HTTP HTTP HTTP HTTP HTTP

separate process inside example.com firewall

class
ShoutMiddleware 

def
initialize(app) 



@app
=
app 

end 
 

def
call(env) 



status,
headers,
body
=
@app.call(env) 



parts
=
[] 



body.each
{
|part|
parts
<<
part.upcase
} 



[status,
headers,
parts] 

end end

Middleware

class
ShoutMiddleware 

def
initialize(app) 



@app
=
app 

end 
 

def
call(env) 



status,
headers,
body
=
@app.call(env) 



parts
=
[] 



body.each
{
|part|
parts
<<
part.upcase
} 



[status,
headers,
parts] 

end end

Middleware

app
=
lambda
{
|env| 

[200,
{'Content‐Type'=>'text/plain'},
["hello
world"]]
} stream
=
ShoutMiddleware.new(app) Rack::Handler::Mongrel.run(stream,
:Port
=>
8080)

Rack::ETag

require
'digest/md5' module
Rack 

class
ETag 



def
initialize(app) 





@app
=
app 



end 
 



def
call(env) 





status,
headers,
body
=
@app.call(env) 





if
!headers.has_key?('ETag') 







parts
=
[] 







body.each
{
|part|
parts
<<
part.to_s
} 







headers['ETag']
=
%("#{Digest::MD5.hexdigest(parts.join(""))}") 







[status,
headers,
parts] 





else 







[status,
headers,
body] 





end 



end 

end end

Rack Middleware

Rack::Chunked Rack::ContentLength Rack::ConditionalGet Rack::ContentType Rack::Deflater Rack::ETag Rack::Head Rack::MethodOverride Rack::Runtime Rack::Sendfile Rack::ShowStatus Rack::CommonLogger Rack::Lint Rack::Lock Rack::Reloader Rack::Cascade Rack::Recursive Rack::Static Rack::URLMap

Routing Behavioral Content Modifying

<http://github.com/rack/rack/tree/master/lib/rack>

Rack::Contrib

Rack::AcceptFormat Rack::Access Rack::Backstage Rack::Callbacks Rack::Config Rack::Cookies Rack::CSSHTTPRequest Rack::Deflect Rack::Evil Rack::HostMeta Rack::JSONP Rack::LighttpdScriptNameFix Rack::Locale Rack::MailExceptions Rack::NestedParams Rack::NotFound Rack::ProcTitle Rack::Profiler Rack::ResponseCache Rack::ResponseHeaders Rack::RelativeRedirect Rack::Signals Rack::StaticCache Rack::SimpleEndpoint Rack::TimeZone

<http://github.com/rack/rack‐contrib>

<http://coderack.org>

<http://coderack.org>

99 Pieces of Middleware

ActionDispatch

• Middleware extracted from ActionController
• ActionDispatch::MiddlewareStack
• Request/Response objects
• Routing
• Integration Testing Support

<http://github.com/rails/rails/tree/master/actionpack/lib/action_dispatch >

$
rake
middleware use
ActionDispatch::Static use
Rack::Lock use
Rack::Runtime use
Rails::Rack::Logger use
ActionDispatch::ShowExceptions use
ActionDispatch::Callbacks use
ActionDispatch::Cookies use
ActionDispatch::Session::CookieStore use
ActionDispatch::Flash use
ActionDispatch::ParamsParser use
Rack::MethodOverride use
ActionDispatch::Head use
ActiveRecord::ConnectionAdapters::ConnectionManagement use
ActiveRecord::QueryCache run
Helloworld::Application.routes

Default Middleware

AD::MiddlewareStack

require
'rack/cache' require
'rack/contrib' module
Helloworld 

class
Application
<
Rails::Application 



#
adds
the
new
middleware
at
the
bottom
of
the
stack 



config.middleware.use
Rack::Cache,
:verbose
=>
true 
 



#
adds
the
new
middleware
before
an
existing
middleware 



config.middleware.insert_before
Rack::Lock,
Rack::ProcTitle 
 



#
adds
the
new
middleware
after
an
existing
middleware 



config.middleware.insert_after
Rack::Head,
Rack::CSSHTTPRequest 
 



#
swap
one
middleware
for
another 



config.middleware.swap
ActionDispatch::ShowExceptions,
SuperShowExceptions 
 



#
remove
a
middleware
from
the
stack 



config.middleware.delete
Rack::MethodOverride 

end end

config/application.rb

Middleware Plugins

require
"rack/cache" module
Cache 

class
Railtie
<
Rails::Railtie 



railtie_name
:rails_cache 
 



initializer
"rails_cache.insert_rack_cache"
do
|app| 





app.config.middleware.use
Rack::Cache, 







:metastore


=>
"file:#{Rails.root
+
"cache/rack/meta"}", 







:entitystore
=>
"file:#{Rails.root
+
"cache/rack/body"}", 







:verbose




=>
true 



end 

end end

<http://boldr.net/upgrade‐plugins‐gems‐rails‐3 >

## Bundle the gems you use: gem "rails-cache", :require => "rails/cache"

rails-cache.gem/lib/rails/cache.rb Gemfile

Rack::Mount

require
'rack/mount' Routes
=
Rack::Mount::RouteSet.new
do
|set| 

#
add_route
takes
a
rack
application
and
conditions
to
match
with 

#
conditions
may
be
strings
or
regexps 

#
See
Rack::Mount::RouteSet#add_route
for
more
options. 

set.add_route
FooApp,
:method
=>
'get',
:path
=>
%{/foo} end 
 #
The
route
set
itself
is
a
simple
rack
app
you
mount run
Routes

<http://github.com/josh/rack‐ mount> config.ru

Rack::Mount

require
'rack/mount' Routes
=
Rack::Mount::RouteSet.new
do
|set| 

#
add_route
takes
a
rack
application
and
conditions
to
match
with 

#
conditions
may
be
strings
or
regexps 

#
See
Rack::Mount::RouteSet#add_route
for
more
options. 

set.add_route
FooApp,
:method
=>
'get',
:path
=>
%{/foo} end 
 #
The
route
set
itself
is
a
simple
rack
app
you
mount run
Routes

<http://github.com/josh/rack‐ mount> config.ru

Rack::Mount

require
'rack/mount' Routes
=
Rack::Mount::RouteSet.new
do
|set| 

#
add_route
takes
a
rack
application
and
conditions
to
match
with 

#
conditions
may
be
strings
or
regexps 

#
See
Rack::Mount::RouteSet#add_route
for
more
options. 

set.add_route
FooApp,
:method
=>
'get',
:path
=>
%{/foo} end 
 #
The
route
set
itself
is
a
simple
rack
app
you
mount run
Routes

<http://github.com/josh/rack‐ mount> config.ru

Actions = Rack Apps

$
rails
console Loading
development
environment
(Rails
3.0.0.beta) >>
action
=
ApplicationController.action(:index) =>
#<ActionController::Metal::ActionEndpoint:0x2290fd4 




@action=:index, 




@controller=ApplicationController, 




@_formats=<stuff>> >>
action.respond_to?(:call) =>
true

Routing to Rack

class
TwitterApp
<
Sinatra::Base 

set
:root,
File.dirname(__FILE__) 
 

get
'/twitter'
do 



@user
=
'raasdnil' 



t
=
Twitter::Search.new(@user).fetch 



@tweets
=
t.results 



erb
:twitter 

end end

<http://lindsaar.net/2010/2/7/rails_3_routing_with_rack >

require
'twitter_app' 
 HelloWorldApp::Application.routes.draw
do
|map| 

match
'/twitter',
:to
=>
TwitterApp end lib/twitter_app.rb config/routes.rb

More Rack + Rails

RailsGuides: Rails on Rack (Updated for Rails 3)

<http://guides.rails.info/rails_on_rack.html>

Scaling Rails: Rack & Metal (Screencast)

<http://railslab.newrelic.com/2009/06/05/episode-14-rack-metal>

Rack API Documentation

<http://rack.rubyforge.org/doc/>

Rack SPEC (Seriously)

<http://rack.rubyforge.org/doc/SPEC.html>

Rack Source (On The GitHub)

<http://github.com/rack/rack>