WebSocket For Web Rubyists
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WebSocket for Web Rubyists @ryudoawaru at OEDO’05
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Transcript of WebSocket For Web Rubyists
WebSocket for Web Rubyists@ryudoawaru at OEDO’05
はじめに発表する機会をいただき ありがとうございます
提 供提 供
五倍紅寶石五倍紅寶石
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
台湾人であり
ルビーストRubeastであり
Rubyの肩書
RubyConf Taiwan執行委員長
Rails Girls Taipei主催人
仕事は
無限虫制師Unlimited Bug WorksGenerator
弊社の業務
Ruby / Rails の 教育業者
コンサルタンシー / オフショア海外の取引先は日本、シンガポールなどを持ちます
Rubyの広めるRailsGirls / RubyConf…etc
RWC初めの海外スポンサーになりました
ここから、英語で話す
Agenda
Introduce WebSocket / EM-Websocket.
Architectural Perception for Web Rubyists.
WebSocketRFC 6455
Websocket
W3C / HTML5 Standard
Standard Javascript API
Full-duplex
Pub-Sub between client and server
Gem Category
EventMachine-Websocket
Faye-Websokcet
EM-Websocket
EM-Websocket
From 2009
Simple implementation
Easily handle c10k by 1 process
http://shokai.org/blog/archives/7149
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
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!!');
How does it workClient 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"
Events
onopen：When new connection is established
onmessage：When new message comes from another side
onclose：When connection is closed by the other side
Methods of Handshake Object
send：Send message to client or server side.
close：Close connection.
Message Flow
Server
Client
Client
Client
1. send msg
2. onmessage
3. Send to all clients
4. onmessage
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
WebSocket Protocol is Simple.
But it’s never easy to make a great product.
Architectural Issue
Application Stack Style
Authentication
Application Stack StyleStandalone or in App?
Two Styles
Standalone
In-App
Standalone
Web Service Stack
WebSocket Service Stack
Normal HTTP Request
WS Request
In App Style
Web Service Logic
Normal HTTP Logic
Normal HTTP Request
WS Request
Live with HTTP Service in the Rack Stack
request.websocket?
Rack Stack
WebSocketOther Rack Stuffs
YES NO
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
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
Standalone or In App?
Normal Web Services
Keeps Connection for very short period.
Process could be terminated w/o affecting any client.
Client Server
open
close
open
close
WebSocket Service
Long-running Connection
Stop process means killing all connections.
Server
Client
Client
Client
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.
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
AuthenticateConfirm identity in handshake
Authentication Issue
Client Server
Handshake Request
Handshake Response
Websocket
Confirm at this point!
Possible Methods to Confirm Identity
Cookie
Headers
URL / Query Parameters
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.
Identify by Request Headers
Unable to add custom header in the JavaScript WebSockets API.
Identify by URL
Client
⓵GET http://host/chat
WebSocketWeb Service
⓷Use ticket to handshake
⓸Identity confirmed
⓶Generate URL: ws://host2/abc1234 as “ticket”
Attention
Security issue:
The “ticket" should be removed from database after connection established.
Should only be valid in a short time.
Showcase
Chatroom for ForumiOS APPWEB
http://www.focus-sport.club.tw/
Serve all platforms by one stack.
Runs Permanently.
Handle more than 1k concurrent connections very easily.
ご清聴ありがとうございました
Any Question?
