Building Web Apps with Rack and Sinatra

Project files and notes at www.blacktm.com

Transcript

1. Building Web Apps with Rack and Sinatra @blacktm
2. Objectives ✔ Describe the HTTP request process ✔ Define Rack, describe its purpose ✔ Build a simple Rack web app ✔ Define, build, and use middleware ✔ Define DSL (compare with “framework”) ✔ Build a simple Sinatra app
3. Things You’ll Need ✔ gem install thin ✔ gem install sinatra ✔ gem install heroku ✔ Project files and notes at blacktm.com
4. HTML CSS JS Rails / Sinatra Ruby Deploy
5. Web Server HTTP Request Middleware Rack Your App
6. Web Server HTTP Request Middleware Rack Your App
7. What is Rack? A modular web server interface. (Connects your Ruby app to the web.)
9. A common interface.
10. Your App Rack Thin WEBrick Mongrel CGI
11. What is a Rack app? A Ruby object that responds to a “call” method, taking a single hash parameter, and returning an array which contains the response status code, response headers, and response body as an array of strings. “In English, please.”
12. $ rackup config.ru Run it! Open “simple_rack” and edit the “config.ru” file. # config.ru - rackup file require 'rack' class MyApp def call(env) headers = { "Content-Type" => "text/html" } [200, headers, ["Hello world!"]] end end run MyApp.new
13. http://0.0.0.0:9292 #=> Hello world! http://0.0.0.0:9292/there/isnt/a/route/here #=> Hello world! A very basic server.
14. Who cares? ✔ You just built a web app. Damn. ✔ Important in understanding (and building) web frameworks (e.g. Rails) ✔ Middleware!
15. HTTP Request Middleware Rack Your App Web Server
16. HTTP Request Middleware Rack Your App Web Server
17. Let’s explore Middleware! 1. Open “rack_middleware” 2. Stop the server (ctrl-c) 3. Run: $ rackup config.ru 4. Open: http://0.0.0.0:9292 or: http://localhost:9292
19. Rack’s Default Middleware (in development mode): Rack::CommonLogger Rack::ShowExceptions Rack::Lint
20. # app.rb class MyApp def call(env) puts "Hello from MyAPP" return [200, {}, ["Hello"]] end end No “Content-Type”
21. Solution? Middleware!
22. class ContentType def initialize(app) @app = app end def call(env) status, headers, body = @app.call(env) puts "Hello from ContentType" # TODO: Add "Content-Type" to the HTTP # headers and return the response. end end Open “config.ru”
23. Add the “Content-Type” to the headers. # TODO: Add "Content-Type" to the HTTP # headers and return the response. headers.merge!( "Content-Type" => "text/html" ) return [status, headers, body]
24. class FinishSentence def initialize(app) @app = app end def call(env) status, headers, body = @app.call(env) puts "Hello from FinishSentence" # TODO: Add " world!" to the HTTP # body and return the response. end end
25. Add the “ world!” to the body. # TODO: Add " world!" to the HTTP # body and return the response. body.push(" world!") return [status, headers, body]
26. Use the middleware. # TODO: Tell the app to use the "ContentType" # and "FinishSentence" middleware. use ContentType use FinishSentence
27. Run it! $ rackup config.ru http://0.0.0.0:9292 127.0.0.1 - - [13/Oct/2012 21:18:58] "GET / HTTP/1.1" 200 12 0.0009
28. rack_middleware:$ rackup config.ru >> Thin web server (v1.5.0 codename Knife) >> Maximum connections set to 1024 >> Listening on 0.0.0.0:9292, CTRL+C to stop Hello from MyAPP Hello from FinishSentence Hello from ContentType 127.0.0.1 - - [14/Nov/2012 17:01:07] "GET / HT {
29. What’s wrong with this?
30. What’s wrong with this?
33. “Sinatra is a DSL for quickly creating web applications in Ruby with minimal e ort.” A “human interface” to Rack. “Domain Specific Language”
35. HTTP Request Middleware Rack Your App Web Server
36. HTTP Request Middleware Rack Your App Web Server
37. HTTP Request Middleware Rack Your App Sinatra Web Server
38. The Showdown Plain ‘ol Rack Sinatra get '/' do "Hello world!" end class MyApp def call(env) headers = { "Content-Type" => "text/html" } [200, headers, ["Hello world!"]] end end
39. $ rackup config.ru Run it! Open “simple_sinatra” and edit the “config.ru” file. # config.ru require 'sinatra' get '/' do "Hello Sinatra!" end run Sinatra::Application
40. What else can do?
41. # config.ru require 'sinatra' get '/' do "Hello Sinatra!" end get '/hello/:name' do |n| "Hello #{n}!" end get '/wildcard/*' do request.inspect end error 404 do "OMG, 404!" end get '/breakit' do 500 end run Sinatra::Application
43. Rails email database ajax orm csrf routes tests sessions models views controllers “A full-stack web application framework.” logging tasks
44. Middleware Rack Your App Rails Web Server Middleware Rack Your App Sinatra Web Server
45. Middleware Rack Your App Web Server Middleware Rack Your App Sinatra Web Server RAILS
50. me
54. Rack + Sinatra + DataMapper + Heroku Messages App
55. Thanks! @blacktm