Rack: HTTP 200 OK

An introduction to HTTP and Ruby's Rack library.

Given to the RIT Society of Software Engineers in 2010. http://sse.se.rit.edu/

Transcript

1. rack: HTTP 200 OK
   nick quaranto
   

   View Slide

2. me
   5th year SE/CS
   bills fan
   ruby fanatic
   gemcutter lead
   

   View Slide

3. this talk is about
   internets
   rubies
   unicorns
   

   View Slide

4. HTTP
   

   View Slide

5. history
   

   View Slide

6. tim berners-lee
   

   View Slide

7. the first web server
   

   View Slide

8. View Slide

9. http 1.0: rfc1945
   http 1.1: rfc2616
   

   View Slide

10. View Slide

11. the protocol
    request => response
    stateless
    

    View Slide

12. requests:
    Request line, such as GET /images/logo.gif
    HTTP/1.1
    Headers, such as Accept-Language: en
    An empty line
    An optional message body
    

    View Slide

13. verbs
    HEAD
    GET
    POST
    PUT
    DELETE
    etc...
    

    View Slide

14. response
    code (200, 404, 500)
    more headers
    body
    

    View Slide

15. codes
    

    View Slide

16. 200s
    

    View Slide

17. 200s
    200 OK
    201 Created
    202 Accepted
    

    View Slide

18. 300s
    

    View Slide

19. 300s
    301 Moved Permanently
    302 Found
    304 Not Modified
    

    View Slide

20. 400s
    

    View Slide

21. 400s
    401 Unauthorized
    403 Forbidden
    404 Not Found
    418 I'm a teapot
    

    View Slide

22. RFC 2324 HTCPCP/1.0 1 April 1998
    In practice, most automated coffee pots cannot
    currently provide additions.
    2.3.2 418 I'm a teapot
    Any attempt to brew coffee with a teapot should
    result in the error code "418 I'm a teapot". The
    resulting entity body MAY be short and stout.
    

    View Slide

23. 500s
    

    View Slide

24. 500s
    500 Internal Server Error
    502 Bad Gateway
    503 Service Unavailable
    

    View Slide

25. headers
    Date: Wed, 09 Dec 2009 15:25:13 GMT
    Content-Type: text/html
    X-Served-By: Apache
    Content-Encoding: gzip
    

    View Slide

26. let's do this
    

    View Slide

27. tip of the iceberg
    sessions
    security
    caching
    proxies
    

    View Slide

28. rack
    

    View Slide

29. history
    servers and webapps can't talk to each other
    CGI (C, Perl, PHP, etc)
    WSGI (Python)
    Ruby....?
    

    View Slide

30. servers
    apache (passenger)
    mongrel
    thin
    unicorn
    and more...
    

    View Slide

31. frameworks
    rails
    merb
    sinatra
    and more...
    

    View Slide

32. View Slide

33. what's in a response?
    code
    headers
    body
    

    View Slide

34. what's in a response?
    code => Integer
    headers => Hash
    body => String
    

    View Slide

35. [200, {'Content-Type' => 'text/plain'}, 'Hello!']
    

    View Slide

36. let's make a rack app
    

    View Slide

37. class Awesome
    def call(env)
    [200, {'Content-Type' => 'text/plain'}, 'AWESOME.']
    end
    end
    

    View Slide

38. lambda { |env| [200, {'Content-Type' => 'text/plain'}, 'AWESOME.'] }
    

    View Slide

39. env what?
    a Hash of environment variables
    PATH_INFO
    QUERY_STRING
    REMOTE_ADDR
    REQUEST_URI
    

    View Slide

40. rackup
    comes with the rack gem
    starts a rack app
    looks at config.ru
    needs an endpoint
    

    View Slide

41. require 'rack/lobster'
    run Rack::Lobster.new
    

    View Slide

42. ,.---._
    ,,,, / `,
    \\\\ / '\_ ;
    |||| /\/``-.__\;'
    ::::/\/_
    {{`-.__.-'(`(^^(^^^(^ 9 `.========='
    {{{{{{ { ( ( ( ( (-----:=
    {{.-'~~'-.(,(,,(,,,(__6_.'=========.
    ::::\/\
    |||| \/\ ,-'/,
    //// \ `` _/ ;
    '''' \ ` .'
    `---'
    

    View Slide

43. # config.ru
    class Awesome
    def call(env)
    [200, {'Content-Type' => 'text/plain'}, 'AWESOME.']
    end
    end
    run Awesome
    

    View Slide

44. middleware
    think of pancakes
    stack them up!
    instead of run, use
    mmm, pancakes
    

    View Slide

45. View Slide

46. class PassThrough
    def initialize(app)
    @app = app
    end
    def call(env)
    @app.call(env)
    end
    end
    

    View Slide

47. I::Rack
    def call(env)
    if env["PATH_INFO"] == "/WMD"
    [
    404,
    {"Content-Type" => "text/plain"},
    "Not found"
    ]
    else
    @app.call(env)
    end
    end
    

    View Slide

48. Rack::Obama
    def call(env)
    if env["CONTENT_TYPE"] == "nobel-prize/peace"
    [
    202,
    {"Content-Type" => "nobel-prize/peace"},
    "Accepted"
    ]
    else
    @app.call(env)
    end
    end
    

    View Slide

49. Rack::Kanye
    

    View Slide

50. def call(env)
    request_uri = env['REQUEST_URI']
    if request_uri =~ /kanye=true/
    env['REQUEST_URI'].gsub!("&kanye=true","")
    @app.call(env)
    else
    req = "http://#{env['HTTP_HOST']}#{request_uri}&kanye=true"
    [
    302,
    {'Location' => "http://kanyelicious.appspot.com/" + req },
    'Redirecting...'
    ]
    end
    end
    

    View Slide

51. useful middlewares
    Rack::Cache
    Rack::Bug
    Rack::Maintenance
    too many to list !SLIDE @@@ text $ rake
    middleware use Rack::Lock use
    ActionController::Failsafe use
    ActionController::Session::CookieStore, #
    use
    ActionController::ParamsParser use
    Rack::MethodOverride use Rack::Head use
    ActiveRecord::ConnectionAdapters::ConnectionM
    use ActiveRecord::QueryCache run
    ActionController::Dispatcher.new @@@
    

    View Slide

52. real world use:
    

    View Slide

53. maintenance mode
    problem: serve gems when running long
    migrations
    rack promotes decoupled architectures
    enable when tmp/maintenanance.txt exists
    

    View Slide

54. normally
    # config.ru
    run Rack::Adapter::Rails.new(:environment => ENV['RAILS_ENV'])
    

    View Slide

55. require File.join('vendor', 'bundler_gems', 'environment')
    require File.join('config', 'environment')
    use Rack::Static,
    :urls => ["/index.html",
    "/favicon.ico",
    "/images",
    "/stylesheets"],
    :root => "public/maintenance"
    use Hostess
    use Rack::Maintenance,
    :file => File.join('public', 'maintenance', 'index.html')
    run Sinatra::Application
    

    View Slide

56. the point(s)
    

    View Slide

57. http is everywhere
    

    View Slide

58. use Rack
    

    View Slide

59. thanks
    

    View Slide