Rack is Spectacular

Barcamp Miami 2010

Transcript

1. Rack is Spectacular Learning Rack by making a cheap Rails knockoff
2. WARNING
   CODE HEAVY HTTP Ruby Rails
3. WARNING
   CODE HEAVY So get the code http://bit.ly/spectac c9c340bb
4. WARNING
   CODE HEAVY NOT READY FOR PRODUCTION c9c340bb
5. Rack • Standard Ruby-HTTP interface • Write (framework) once • Run anywhere (that is Rack-compatible) • Rails, Sinatra, Camping • Mongrel, Passenger, Unicorn
6. A Rack Application use Rack::ContentLength run(proc do [ 200, { 'Content-type' => 'text/plain'}, 'hello world'] end) Response Code Response Headers Response Body c9c340bb config.ru
8. What is Rails • ActionPack • Router - maps URLs to code • Controller - environment for code • View - generating response body • ActiveRecord - database access
9. The Essential Rails • ActionPack • Router - maps URLs to code • Controller - environment for code • View - generating response body • ActiveRecord - database access
10. module Spectacular class App def call(environment) [ 200, { 'Content-type' => 'text/plain'}, 'hello world'] end end end require 'lib/spectacular.rb' use Rack::ContentLength run(Spectacular::App.new) config.ru lib/spectacular/app.rb 0fad6a02
12. module Spectacular class App … def call(environment) method = environment['REQUEST_METHOD'] path = environment['PATH_INFO'] @dispatcher.dispatch method, path, environment rescue => exception error_backtrace exception, environment end private def error_backtrace(exception, environment) exception_info = “some html” [500, { 'Content-type' => 'text/html'}, exception_info] end … end end lib/spectacular/app.rb 2a0d1445 breaks; no dispatcher yet
14. Dispatch & Routing are the most complicated parts of Rails [citation needed]
15. But That’s Okay • We’re not building Rails • It’s okay if we Fail to Scale • Just use an array to map paths to controllers and actions
16. def get_route(path) @routes.detect{ |r| path === r[0] } end … class RoutePen def route(path, controller, method) @routes << [path, controller, method] end end 9cfb9609 lib/spectacular/dispatcher.rb
18. def response_for(method) @method = method send @method [response_code, headers, body] end … def template_file File.join(APP_DIR, 'views', controller_name, "#{@method}.html.haml") end … def body return @body if defined? @body template = File.read template_file engine = Haml::Engine.new template @body = engine.render end ce2f00a3 lib/spectacular/controller.rb
19. class HelloController < Spectacular::Controller def index end end hello world app/controllers/hello_controller.rb app/views/hello/index.html.haml ce2f00a3
21. Wildcards def get_route(path) @routes.detect{ |r| r[0] === path } end lib/spectacular/dispatcher.rb 48b08205
22. === 0 :> /abc/ === 'abc' # => true 0 :> String === 'abc' # => true 0 :> /too+t/ === 'toooooooooot' # => true
23. route /too+t/, TootController, :toot app/routes.rb A Wildcard Route 48b08205
24. Using the Path class TootController < Spectacular::Controller def toot @toot = @path.gsub('/','') end end app/controllers/toot_controller.rb %h1=@toot app/views/toot/toot.html.haml 48b08205
27. 404 • When we can’t figure out how to process a request, that should be a “404” • We can simply make a wildcard route
28. route //, ErrorController, :not_found app/routes.rb class ErrorController < Spectacular::Controller def not_found @response_code = 404 end end app/controllers/error_controller.rb 2a2653b2
30. What’s Left • Only renders HAML • No layouts • Can’t easily render a different view • No query parameters • No POST
31. thanks • Bryce Kerley; mercenary developer • bkerley@brycekerley.net • http://twitter.com/bonzoesc • Code on Github: http://bit.ly/spectac