1. Rack Middleware
David Dollar

2. What is Rack?

3. A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

4. lambda do |environment|
[ 200, { 'Content-Type' => 'text/plain' }, [ 'OK' ] ]
end
A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

5. lambda do |environment|
[ 200, { 'Content-Type' => 'text/plain' }, [ 'OK' ] ]
end
A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

6. lambda do |environment|
[ 200, { 'Content-Type' => 'text/plain' }, [ 'OK' ] ]
end
A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

7. lambda do |environment|
[ 200, { 'Content-Type' => 'text/plain' }, [ 'OK' ] ]
end
A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

8. lambda do |environment|
[ 200, { 'Content-Type' => 'text/plain' }, [ 'OK' ] ]
end
A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

9. lambda do |environment|
[ 200, { 'Content-Type' => 'text/plain' }, [ 'OK' ] ]
end
A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

10. lambda do |environment|
[ 200, { 'Content-Type' => 'text/plain' }, [ 'OK' ] ]
end
A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

11. lambda do |environment|
[ 200, { 'Content-Type' => 'text/plain' }, [ 'OK' ] ]
end
A Rack application is a Ruby object that responds to call.
It takes exactly one argument, the environment.
It returns an Array of exactly three values:
The status, the headers, and the body.
The headers should respond to each and yield key/value pairs.
The body should respond to each and yield String objects.

12. Rack and Rails

13. Before Rails 2.3

14. Before Rails 2.3
Apache

15. Before Rails 2.3
Apache Passenger

16. Before Rails 2.3
Apache Passenger Rails

17. Before Rails 2.3
Apache Passenger Rails
After Rails 2.3

18. Before Rails 2.3
Apache Passenger Rails
After Rails 2.3
Apache

19. Before Rails 2.3
Apache Passenger Rails
After Rails 2.3
Apache Passenger

20. Before Rails 2.3
Apache Passenger Rails
After Rails 2.3
Apache Passenger Rails

21. Before Rails 2.3
Apache Passenger Rails
After Rails 2.3
Apache Passenger Rails

22. Passenger ActionController::Base#call(env) Rails

23. What is Rack
Middleware?

24. Passenger ActionController::Base#call(env) Rails

25. Passenger Middleware Rails

26. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

27. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

28. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

29. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

30. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

31. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

32. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

33. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

34. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, do_api_call(env) ]
else
env['mydata'] = 'test'
@next_in_chain.call(env)
end
end
end

35. Example

36. Existing Middleware

37. Rack::Cache
http://github.com/rtomayko/rack-cache

38. App Server Rack::Cache Rails
Storage

39. App Server Rack::Cache Rails
Storage

40. Rack::Bug
http://github.com/brynary/rack-bug

44. Rack::OpenID
http://github.com/josh/rack-openid

45. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

46. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

47. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

48. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

49. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

50. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

51. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

52. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

53. class SessionsController
def new
render :new # contains a textbox called quot;identityquot;
end
def create
if openid = request.env['rack.openid.response']
case openid.status
when :success # ...
when :failure # ...
end
else
response.headers['WWW-Authenticate'] = Rack::OpenID.build_header(
:identifier => params[:identity]
)
render :text => '', :status => 401
end
end
end

54. Rack::Debug
http://github.com/ddollar/rack-debug

55. # app/controllers/users_controller.rb
@user = User.find(params[:id])
debugger
render :show
# run the rake task,
$ rake debug
Connected.
# refresh a page in your browser, your app will break at debugger statements
(rdb:1) p @user
<User id: 1, name: quot;David Dollarquot;, email: quot;ddollar@gmail.comquot;>

56. # app/controllers/users_controller.rb
@user = User.find(params[:id])
debugger
render :show
# run the rake task
$ rake debug
Connected.
(rdb:1) p @user
<User id: 1, name: quot;David Dollarquot;, email: quot;ddollar@gmail.comquot;>

57. # app/controllers/users_controller.rb
@user = User.find(params[:id])
debugger
render :show
# run the rake task
$ rake debug
Connected.
(rdb:1) p @user
<User id: 1, name: quot;David Dollarquot;, email: quot;ddollar@gmail.comquot;>

58. # app/controllers/users_controller.rb
@user = User.find(params[:id])
debugger
render :show
# run the rake task
$ rake debug
Connected.
(rdb:1) p @user
<User id: 1, name: quot;David Dollarquot;, email: quot;ddollar@gmail.comquot;>

59. Using Middleware

60. Passenger Middleware Rails
class ExampleMiddleware
def initialize(next_in_chain)
@next_in_chain = next_in_chain
end
def call(env)
if env['PATH_INFO'] =~ Regexp.new('^/api')
[ 200, { 'Content-Type' => 'text/xml' }, '<?xml?>' ]
else
@next_in_chain.call(env)
end
end
end

61. Passenger Middleware Rails
class ExampleMiddleware
# ...
end
# config/environment.rb
config.middleware.use 'ExampleMiddleware'

62. Passenger Middleware Rails
class ExampleMiddleware
# ...
end
# config/environment.rb
config.middleware.use 'ExampleMiddleware'

63. Passenger Middleware Sinatra
class ExampleMiddleware
# ...
end
app = Rack::Builder.new do
use ExampleMiddleware
run MySinatraApp.new
end

64. Passenger Middleware Sinatra
class ExampleMiddleware
# ...
end
app = Rack::Builder.new do
use ExampleMiddleware
run MySinatraApp.new
end

65. Passenger Middleware Sinatra
class ExampleMiddleware
# ...
end
app = Rack::Builder.new do
use ExampleMiddleware
run MySinatraApp.new
end

66. class ExampleMiddleware
# ...
end
# Rails
config.middleware.use 'ExampleMiddleware'
# Rack::Builder
app = Rack::Builder.new do
use ExampleMiddleware
run MySinatraApp.new
end

67. class ExampleMiddleware
# ...
end
# Rails
config.middleware.use 'ExampleMiddleware'
config.middleware.use 'ExampleMiddlewareTwo'
# Rack::Builder
app = Rack::Builder.new do
use ExampleMiddleware
use ExampleMiddlewareTwo
run MySinatraApp.new
end

68. class ExampleMiddleware
# ...
end
# Rails
config.middleware.use 'ExampleMiddleware'
config.middleware.use 'ExampleMiddlewareTwo'
config.middleware.use 'ExampleMiddlewareThree'
# Rack::Builder
app = Rack::Builder.new do
use ExampleMiddleware
use ExampleMiddlewareTwo
use ExampleMiddlewareThree
run MySinatraApp.new
end

69. Questions?