Rack is a Ruby web server interface specification that provides a minimal abstraction between web servers and web applications. It standardizes how web requests and responses are handled, allowing applications to ignore differences between web servers and focus on the application code. Rack allows web applications to be run on many different web servers without changing code. Developers can also add middleware between the web server and application code to modify requests and responses.

1. SOMETHING SOMETHING RACK

2. OH, HI!
• Joren
• Openminds
• @joren
• tech.jorendegroof.be

3. OVERVIEW
• Rack what?
• Why Rack?
• How do you use it?
• Middleware

4. RACK WHAT?

5. RACK WHAT?
Rack is a specification (and implementation) of a minimal
abstract Ruby API that models HTTP

6. WHY RACK?
• Stop writing handlers for every webserver
• Keep the request and response simple

7. WHY RACK?
Supported web servers

8. WHY RACK?
Supported web frameworks

9. HOW DO YOU USE IT?
How to call it?
lambda { |env|
[
200,
{
‘Content-Type’ => ‘text/plain’,
‘Content-Lenght’ => ‘5’,
},
[‘Hello’]
]
}

10. HOW DO YOU USE IT?

11. HOW DO YOU USE IT?
How to call it?
lambda { |env|
[
200,
{
‘Content-Type’ => ‘text/plain’,
‘Content-Lenght’ => ‘5’,
},
[‘Hello’]
]
}

12. HOW DO YOU USE IT?
How to call it?
lambda { |env|
[
200,
{
‘Content-Type’ => ‘text/plain’,
‘Content-Lenght’ => ‘5’,
},
[‘Hello’]
]
}

13. HOW DO YOU USE IT?
How to call it?
lambda { |env|
[
200,
{
‘Content-Type’ => ‘text/plain’,
‘Content-Lenght’ => ‘5’,
},
[‘Hello’]
]
}

14. HOW DO YOU USE IT?
How to call it?
lambda { |env|
[
200,
{
‘Content-Type’ => ‘text/plain’,
‘Content-Lenght’ => ‘5’,
},
[‘Hello’]
]
}

15. HOW DO YOU USE IT?
How to call it?
lambda { |env|
[
200,
{
‘Content-Type’ => ‘text/plain’,
‘Content-Lenght’ => ‘5’,
},
[‘Hello’]
]
}

16. HOW DO YOU USE IT?
How to call it?
lambda { |env|
[
200,
{
‘Content-Type’ => ‘text/plain’,
‘Content-Lenght’ => ‘5’,
},
[‘Hello’]
]
}

17. HOW DO YOU USE IT?
How to call it?
run lambda { |env|
[
200,
{
‘Content-Type’ => ‘text/plain’,
‘Content-Lenght’ => ‘5’,
},
[‘Hello’]
]
}

18. config.ru

19. $ rackup config.ru

20. $ curl http://localhost:9292

21. Hello

22. HOW DO YOU USE IT?
class HelloWorld
def call(env)
[200, {"Content-Type" => "text/plain"}, ["Hello World!"]]
end
end

23. env

24. REQUEST_METHOD

25. env[‘REQUEST_METHOD’]

26. GET
PUT
POST
DELETE
HEAD
OPTIONS
TRACE

27. PATH_INFO

28. /items/123

29. HTTP_*

30. HTTP_ACCEPT

31. rack.*

32. yournamespace.*

33. request = Rack::Request.new(env)

34. request.post?

35. HOW DO YOU USE IT?
Example

36. MIDDLEWARE
Middleware App
HTTP

37. use Middleware A
use Middleware B
use Middleware C
run app

38. class GoSlower
def initialize(app)
@app = app
end
def call(env)
sleep(1)
@app.call(env)
end
end

39. class GoSlower
def initialize(app)
@app = app
end
def call(env)
sleep(1)
@app.call(env)
end
end

40. class GoSlower
def initialize(app)
@app = app
end
def call(env)
sleep(1)
@app.call(env)
end
end

41. class GoSlower
def initialize(app)
@app = app
end
def call(env)
sleep(1)
@app.call(env)
end
end

42. IN YOUR RAILS APP
#environment.rb
config.middleware.use “Rack::GoSlower”
config.middleware.use “Rack::Cache”,
:verbose => true,
:metastrore => ‘file:/path/to/dir’,
:entitystore => 'memcached://localhost:11211/body'

43. EXAMPLES

44. RACK::HONEYPOT
http://github.com/sunlightlabs/rack-honeypot

45. RACK::CACHE
http://github.com/rtomayko/rack-cache

46. WARDEN + DEVISE
http://github.com/hassox/warden
http://github.com/plataformatec/devise

47. RACK::DEBUG
http://github.com/ddollar/rack-debug

48. RACK::GEOIP
http://github.com/b/rack-geoip

49. RACK::GOOGLE-ANALYTICS
http://github.com/leehambley/rack-google-analytics

50. RACK::REWRITE
http://github.com/jtrupiano/rack-rewrite

51. RACK::MOBILE-DETECT
http://github.com/talison/rack-mobile-detect

52. RACK::CONTRIB
http://github.com/rack/rack-contrib

53. QUESTIONS?