WebSocket For Web Rubyists
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This document introduces WebSocket and how it can be used for real-time communication between a client and server. It discusses: 1. The basics of WebSocket including how the handshake process works and how events and messages are exchanged. 2. Two approaches for integrating WebSocket into a Ruby/Rails application - as a standalone service or within the application stack. Using it standalone allows the service to run independently while integrating it brings challenges in handling long-running connections. 3. Key considerations for WebSocket including authentication, concurrency models, and whether the server process needs to run permanently to maintain open connections.
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WebSocket For Web Rubyists
- 1. WebSocket for Web Rubyists @ryudoawaru at OEDO’05
- 4. 自己紹介 鄧 慕凡（テン ムファン） a.k.a: 竜堂 終 両方どもある小説の登場人物 Github / Twitter: @ryudoawaru http://ryudo.tw
- 5. 台湾人であり
- 7. Rubyの肩書
- 10. 仕事は
- 13. 弊社の業務
- 14. Ruby / Rails の 教育業者
- 18. ここから、英語で話す
- 19. Agenda Introduce WebSocket / EM-Websocket. Architectural Perception for Web Rubyists.
- 21. Websocket W3C / HTML5 Standard Standard Javascript API Full-duplex Pub-Sub between client and server
- 25. EM-Websocket
- 26. EM-Websocket From 2009 Simple implementation Easily handle c10k by 1 process http://shokai.org/blog/archives/7149
- 27. Typical Server Side Code EventMachine::WebSocket.start(:host => "0.0.0.0", :port => 8080) do |ws| ws.onopen { ws.send "Hello Client!"} ws.onmessage { |msg| ws.send "Pong: #{msg}" } ws.onclose { puts "WebSocket closed" } end
- 28. Typical Client Side Code var ws = new WebSocket('ws://host/uri'); ws.onopen = function() { show('websocket opened'); }; ws.onclose = function() { show('websocket closed'); } ws.onmessage = function(m) { show('websocket message: ' + m.data); }; ws.send('Hello Websocket!!');
- 29. How does it work Client Server Handshake Response Websocket Handshake Request GET /chat HTTP 1.1 Host: server.host.com Upgrade: Websocket Connection: Upgrade Origin: http://host.com Sec-Websocket-Key: “WwV7thr/Uwrg3mA57risrQ==" Sec-WebSocket-Version:"13" Connection:”Upgrade" Sec-WebSocket-Accept: F0VaFFGV/ JHx1hJWBlhuJAqdse8= Upgrade:"websocket"
- 30. Events onopen：When new connection is established onmessage：When new message comes from another side onclose：When connection is closed by the other side
- 31. Methods of Handshake Object send：Send message to client or server side. close：Close connection.
- 32. Message Flow Server Client Client Client 1. send msg 2. onmessage 3. Send to all clients 4. onmessage
- 33. Basic EM-WebSocket Code Style conns_in_channel = Set.new EM::WebSocket.start(...) do |ws| ws.onopen do |request| conns_in_channel.add ws end ws.onmessage do |msg| conns_in_channel.each do |conn| EM.next_tick{conn.send(msg)} end end ws.onclose do conns_in_channel.delete ws end end Store connection Remove connection on quit Set to store connection Send msg to connections 1 by 1
- 35. But it’s never easy to make a great product.
- 36. Architectural Issue Application Stack Style Authentication
- 37. Application Stack Style Standalone or in App?
- 39. Standalone Web Service Stack WebSocket Service Stack Normal HTTP Request WS Request
- 40. In App Style Web Service Logic Normal HTTP Logic Normal HTTP Request WS Request
- 41. Live with HTTP Service in the Rack Stack request.websocket? Rack Stack WebSocketOther Rack Stuffs YES NO
- 42. Identify by Request Headers # middlewares/chat_backend.rb def call(env) if Faye::WebSocket.websocket?(env) # WebSockets logic goes here ws.rack_response else @app.call(env) end end https://devcenter.heroku.com/articles/ ruby-websockets
- 43. Identify by Request Headers # config/routes.rb Example::Application.routes.draw do match "/websocket", :to => ActionCable.server, via: [:get, :post] end https://github.com/rails/actioncable
- 45. Normal Web Services Keeps Connection for very short period. Process could be terminated w/o affecting any client. Client Server open close open close
- 46. WebSocket Service Long-running Connection Stop process means killing all connections. Server Client Client Client
- 47. Concurrency Model WebSocket Gems use one of following concurrency models: Reactor: EventMachine based Gems. Thread: Tubesock. Mixed: ActionCable This may conflicts with model of your normal Web Services.
- 48. Comparison of Connection Features Normal Web Works WebSocket Connection Period short long Concurrency Model Depend on App Server Reactor or Thread Process Long- Running? No Yes
- 49. Authenticate Confirm identity in handshake
- 50. Authentication Issue Client Server Handshake Request Handshake Response Websocket Confirm at this point!
- 51. Possible Methods to Confirm Identity Cookie Headers URL / Query Parameters
- 52. Identify by Cookie Easy approach for web developers. WebSocket may run at different host. Some browsers don’t support cookie on ws:// request. Most mobile APP’s http client may not support cookie/session by default.
- 53. Identify by Request Headers Unable to add custom header in the JavaScript WebSockets API.
- 54. Identify by URL Client GET http://host/chat WebSocketWeb Service Use ticket to handshake Identity confirmed Generate URL: ws://host2/abc1234 as “ticket”
- 55. Attention Security issue: The “ticket" should be removed from database after connection established. Should only be valid in a short time.
- 56. Showcase
- 57. Chatroom for Forum iOS APPWEB
- 58. http://www.focus-sport.club.tw/ Serve all platforms by one stack. Runs Permanently. Handle more than 1k concurrent connections very easily.
- 59. ご清聴ありがとうございました
- 60. Any Question?