Based on original presentation by Dan Webb http://slidesha.re/dan_on_rack Added some bits about Rails at the end, instead of other examples he had originally.

1. 8 minutes on
Rack
based on a presentation by
Dan Webb (dan@danwebb.net)
@danwrong
http://slidesha.re/dan_on_rack

5. A Convention

6. If you have a
Ruby object...

7. that has a call method which takes
one argument...
app.call(env)

8. and that method returns an array
with 3 elements...
[200, { 'Content-Type' => 'text/plain' }, 'Hello World!']

9. then you can connect it to any web
server that supports Rack
require 'thin'
Rack::Handler::Thin.run(app, :Port => 4000)

10. and you've got
yourself a web
application

11. That's it.

12. For Example...

13. app = Proc.new do |env|
[200, { 'Content-Type' => 'text/plain' },
'Hello World!']
end
require 'rubygems'
require 'thin'
Rack::Handler::Thin.run(app, :Port => 4000)

14. class HelloWorld
def initialize(name)
@name = name
end
def call(env)
[200, { 'Content-Type' => 'text/plain' },
"Hello #{@name}!"] end
end
require 'rubygems'
require 'rack'
Rack::Handler::Mongrel.run(HelloWorld.new("Dan"),
:Port => 4000)

15. def call(env)

16. {
"SERVER_NAME"=>"localhost",
"HTTP_ACCEPT_ENCODING"=>"gzip,deflate",
"HTTP_USER_AGENT"=>"Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en- GB;
rv:1.9.0.4) Gecko/2008102920 Firefox/3.0.4",
"PATH_INFO"=>"/",
"SCRIPT_NAME"=>"",
"SERVER_PROTOCOL"=>"HTTP/1.1",
"HTTP_ACCEPT_LANGUAGE"=>"en-gb,en;q=0.5",
"HTTP_HOST"=>"localhost:4000",
"REMOTE_ADDR"=>"127.0.0.1",
"HTTP_KEEP_ALIVE"=>"300",
"REQUEST_PATH"=>"/",
"SERVER_SOFTWARE"=>"thin 0.8.2 codename Double Margarita",
"HTTP_ACCEPT_CHARSET"=>"ISO-8859-1,utf-8;q=0.7,*;q=0.7",
"HTTP_VERSION"=>"HTTP/1.1", "REQUEST_URI"=>"/",
"SERVER_PORT"=>"4000",
"QUERY_STRING"=>"",
"GATEWAY_INTERFACE"=>"CGI/1.2",
"HTTP_ACCEPT"=>"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
"HTTP_CONNECTION"=>"keep-alive",
"REQUEST_METHOD"=>"GET"
}

17. [200, { 'Content-Type' => 'text/plain' }, "Hello #{@name}!"]
Status Code

18. [200, { 'Content-Type' => 'text/plain' }, "Hello #{@name}!"]
HTTP Headers

19. [200, { 'Content-Type' => 'text/plain' }, "Hello #{@name}!"]
Response Body

20. Response body can be any
object that respond_to?(:each)
file = File.new('myfile.xml')
[200, { 'Content-Type' => 'application/xml' }, file]

21. For Example...

22. class StreamingFile
def initialize(file)
@file = file
end
def length
File.size(@file)
end
def last_modified
File.mtime(@file).rfc822
end
def each
File.open(@file, "rb")
do |file|
while part = file.read(8192)
yield part
end
File.delete(@file)
end
end

23. [200, {
'Content-Type' => 'audio/mp3',
'Content-Length' => file.length.to_s
}, file]

24. Duck Typing!
• Streaming
• Clean up after response sent
• Complex responses
• Loads more...

25. Why?

26. Common interface

27. • Passenger
• Mongrel
• CGI
• SCGI
• FastCGI
• Thin
• Ebb
• Fuzed
• Webrick
• Litespeed

28. Write once,
serve however...

29. Convienient way
to write
micro apps

30. There's More...
• The Rack Gem
• Middleware
• Rack and Passenger
• rackup

31. rack.rubyforge.org

32. What about Rails?

33. Rails is
a Rack Application

34. config.ru
# This file is used by Rack-based servers to start
the application.
require ::File.expand_path('../config/environment',
__FILE__)
run MyApp::Application

35. routes.rb
# You can call any Rack app from a route
match "/foo" => MySinatraApp
match "/bar" => MyMiddleware.new(OtherApp)

36. Questions?
Original Presentation by Dan Webb, @danwrong
Modified with Rails examples by Sarah Allen
@ultrasaurus, Blazing Cloud