SocketStream

2. A web framework for single page apps

3. Created by Owen Barnes @temporalwave ! ! (my boss at a former company)

4. About me Paul Jensen @paulbjensen ! ! (I’m the new lead developer)

5. Where to begin?

6. Why Single Page Apps?

7. With a traditional web app, the user has to refresh the page to see new information

8. Client Server Time

9. GET/football/live Client Server Time HTTP/1.1

10. HTTP/1.1 200 OK Client Server Time

11. 20 seconds later… Client Server Time

12. I wonder what the latest score is… Let’s reload the page Client Server Time

13. GET/football/live Client Server Time HTTP/1.1

14. HTTP/1.1 304 Not Modified Client Server Time

16. The user had to press F5 to get at any new information Client Server Time

17. Client Server Time Even though there was no new information, the server still had to serve the HTTP request

18. This is not a fun experience

19. How do we make this better?

21. We could use AJAX to update the page

22. We’d save the user having to press the F5 key

23. What else can we do?

25. Optimise the response

26. GZIP the response data, and …

27. Avoid sending data we already have on the client

28. We could also separate the HTML from the data

29. Reuse the HTML on the client

30. …and use the server to provide you with just data

31. And the web site becomes a client Web App Native App Server API User

32. The server is just an API

33. A beautiful separation of concerns

34. Overview • The server becomes a REST API serving JSON • HTML compilation is done on the client • As a result, less processing & bandwidth is consumed by the server

35. Why Realtime?

37. Polling the server every [n] seconds for new data is redundant

38. There has to be a better way

39. What if the server could send its client(s) new data as soon as it came about?

40. We can, thanks to WebSockets

41. WebSockets allows data to be sent both ways

43. Client Server Time Goal

44. The server sends a message to the client that an action has occurred Client Server Time Goal

45. We eliminate the need to poll the server for new data

46. Overview • We can replace AJAX polling with WebSockets, and provide a better user experience as a result • We also remove the need to make redundant polling requests back to the server. • We use WebSockets for sending/receiving JSON

47. Single Page Apps + The Realtime Web

48. There are many ways to build this kind of app

49. You could build it mostly from scratch, and use Express + Socket.io

50. Or alternatively, you could use a web framework like Meteor or Firebase

51. SocketStream is somewhere in-between these 2 approaches

52. It provides tools to help with building realtime single page apps...

53. ... Whilst trying not to restrict what technologies you can use with your app

54. For example, we don't provide an ORM. Instead, you choose the database & the ORM

55. Also, we don't mandate using a specific client-side framework ! You can use BackBone, Angular, Ember, or something else, that is entirely your choice.

56. What we focus on instead are these things:

57. HTML / CSS / JS code preprocessing Minifying CSS/JS for production use Client-side code organisation HTML Templates WebSocket Management Live Reload Building RPC APIs Building PubSub APIs Session Management Building custom APIs on top of WS Web Workers Connect middleware compatibility

58. I'll run through each of these, 1-by-1. But first, let's look at how to use SocketStream

59. Getting started npm install -g socketstream ! socketstream new my_app

60. Getting started ! ! ! ! Success! Created app 'my_app' with: ✓ Basic chat demo (-m for minimal install) ✓ Javascript example code (-c if you prefer CoffeeScript) ✓ Plain HTML for views (-j if you prefer Jade) Next, run the following commands: cd my_app [sudo] npm install To start your app: node app.js 

61. Here's what the initial file/ folder structure looks like

63. Client code is organised into 5 sub-folders

64. Client side code organisation • CODE stores client side JavaScript files and libraries • CSS stores CSS files • STATIC stores public files like images, font files, and other assets • TEMPLATES stores HTML templates for the single page app to render on the client • VIEWS stores HTML files that are rendered from the server for the initial page

65. Those sub-folders have subfolders, but are optional

66. This is how we load them // My SocketStream 0.3 app ! var http = require('http'), ss = require('socketstream'); ! // Define a single-page client called 'main' ss.client.define('main', { view: 'app.html', css: ['libs/reset.css', 'app.styl'], code: ['libs/jquery.min.js', 'app'], tmpl: '*' }); ! // Serve this client on the root URL ss.http.route('/', function(req, res){ res.serveClient('main'); });

67. // My SocketStream 0.3 app ! var http = require('http'), ss = require('socketstream'); ! // Define a single-page client called 'main' ss.client.define('main', { view: 'app.html', css: ['libs/reset.css', 'app.styl'], code: ['libs/jquery.min.js', 'app'], tmpl: '*' }); ! // Serve this client on the root URL ss.http.route('/', function(req, res){ res.serveClient('main'); });

73. SocketStream uses Browserify to handle requiring JS files

74. Browserify allows us to use a Node.js style of requiring JS files

75. // This file automatically gets called first by SocketStream and must always exist ! // Make 'ss' available to all modules and the browser console window.ss = require('socketstream'); ! ss.server.on('disconnect', function(){ console.log('Connection down :-('); }); ! ss.server.on('reconnect', function(){ console.log('Connection back up :-)'); }); ! ss.server.on('ready', function(){ ! ! ! // Wait for the DOM to finish loading jQuery(function(){ // Load app require('/app'); }); });

76. // This file automatically gets called first by SocketStream and must always exist ! // Make 'ss' available to all modules and the browser console window.ss = require('socketstream'); ! ss.server.on('disconnect', function(){ console.log('Connection down :-('); }); ! ss.server.on('reconnect', function(){ console.log('Connection back up :-)'); }); ! ss.server.on('ready', function(){ ! ! ! // Wait for the DOM to finish loading jQuery(function(){ // Load app require('/app'); }); });

78. Over the years, developers have come up with new languages to generate HTML, CSS, and JavaScript

79. SocketStream allows developers to use these code preprocessors in their apps

80. Adding a preprocessor is simple // Code Formatters ss.client.formatters.add(require('ss-stylus'));

81. For Javascript • SS-COFFEE - supports using CoffeeScript • SS-GORILLA - supports using GorillaScript

82. For CSS • SS-STYLUS - supports using Stylus • SS-LESS - supports using Less

83. For HTML Views • SS-JADE - supports using Jade

84. For HTML Templating • SS-HOGAN - supports using Twitter's Hogan.js • SS-COFFEEKUP - supports using CoffeeKup

85. Setting a Templating engine // Use server-side compiled Hogan (Mustache) templates. Others engines available ss.client.templateEngine.use(require('ss-hogan'));

87. Having to press F5 to reload the page in order to view changes to HTML/CSS/JS...

88. ... is not a fun experience

89. In development mode, SocketStream will watch the client files for changes, and reload the page when they occur

90. In the case of CSS, SocketStream will apply the changes without reloading the page

92. Client-side HTML templates are made available to the browser via the ss.tmpl object

95. When you're building a single page app, you'll have a lot of JS files, and maybe a few CSS files

96. But serving a HTML page with lots of these files can take time, and is inefficient

97. SocketStream provides a way to concatenate, minify, and GZip these files into 1 JS and 1 CSS file

98. This saves bytes being transferred, as well as reducing the number of HTTP requests you make

99. Also, you can tell SocketStream to load these files from a CDN

100. Setting a Templating engine // Minimize and pack assets if you type: SS_ENV=production node app.js if (ss.env === 'production') ss.client.packAssets();

102. Web Workers are handy for intensive client-side JS operations

103. SocketStream provides support for using Web Workers in your app

104. First, create a folder

105. Next, put your web worker files in that folder

106. Then, load the worker in a client code file, and enjoy

108. SocketStream uses Connect middleware to support HTTP features

109. SocketStream uses the following middleware by default: • compress - for GZipping assets • cookieParser - for handling user tracking • favicon - for serving a favicon.ico ﬁle • session - for handling sessions • static - for serving static assets

110. SocketStream uses the following middleware by default: • compress middleware is loaded ﬁrst, before all other middleware • static middleware is loaded last, after all other middleware

111. SocketStream provides a way to load custom middleware into the connect stack

112. ss.http.middleware.prepend() ss.http.middleware.append()

113. This allows you to use all of the connect middleware out there today, i.e. EveryAuth

115. We use connect’s session middleware, so authentication can be done with either EveryAuth, PassportJS, or you can roll your own.

116. We also recommend using connect-redis

117. Both HTTP and WebSocket interfaces can get/set the session data

118. Via HTTP // app.js ss.http.router.on('/updateSession', function(req, res) { req.session.myVar = 4321; res.end('req.session.myVar has been updated to', req.session.myVar); });

119. Via WebSockets

121. RPC is a common pattern for clients requesting data from the server

122. SocketStream provides a way to construct RPC APIs with flexibility

126. PubSub is a great pattern for Single Page Apps

127. SocketStream handles this in various ways:

128. 1 - Publishing to everyone viewing the app right now Server ss.publish.all('newMessage', message); // Broadcast the message to everyone Client // Listen out for newMessage events coming from the server ss.event.on('newMessage', function(message) { // do something with the message });

129. 2 - Sending to private channels Server (subscribe/unsubscribe the session ) // in a /server/rpc file after calling req.use('session') middleware ! req.session.channel.subscribe('disney') ! req.session.channel.unsubscribe('kids') ! req.session.channel.reset() // unsubscribes the session from every channel req.session.channel.list() // shows what channels are subscribed to !

130. 2 - Sending to private channels Server (publish to channel) // in a /server/rpc file ss.publish.channel('disney', 'chatMessage', {from: 'jerry', message: 'Has anyone seen Tom?'}); Client (receive channel message) // in a /client/code file ss.event.on('chatMessage', function(msg, channelName){ console.log('The following message was sent to the ' + channelName + ' channel:', msg); });

131. 3 - Sending to users Server // in a /server/rpc file ss.publish.user('fred', 'specialOffer', 'Here is a special offer just for you!');

132. 4 - Sending to a browser tab Server // in a /server/rpc file ss.publish.socketId('254987654324567', 'justForMe', 'Just for one tab');

134. On top of RPC and PubSub, SocketStream provides you with a way to create custom request responders

135. Request Response is basically a WebSocket message handler

136. It allows you to write message handling for games, where every byte matters

138. WebSockets are not immortal…

139. They are mangled by mobile networks…

140. Blocked by firewalls…

141. Routed to dead ends by proxy servers

142. And severed by train tunnels

143. Also, browser support for WebSockets isn’t guaranteed

144. You need a transport strategy

145. Originally, SocketStream used Socket.io

146. But Socket.io asserted that if a browser supported WebSockets, then it would work

147. They learned from this, by building Engine.io

148. I created the transport wrapper for Engine.io in SocketStream for Bechtel & Dashku

149. And designed it to reconnect the client when severed

150. Months later, it made it’s way into SocketStream’s core.

151. SocketStream let’s you use this, alongside SockJS

152. …and that is SocketStream in a nutshell. Whew!

153. Let’s look at some SocketStream apps in the wild

154. Hollow hollowdocumentary.com

155. Vmux vmux.co

156. Dashku dashku.com

157. SocketStream plugins

158. SS-BACKBONE

159. SS-ANGULAR

160. SS-CUCUMBER

161. Tips for deploying SocketStream in production

162. 1 - Check your server’s ulimit configuration (This can bite you hard)

163. I learned this when Dashku went #1 on Hacker News in 45min

164. 2 - Use HTTPS, but handle it at the load balancer level rather than at the app level

165. HTTPS helps to improve the stability of WebSocket connections, especially on mobile devices

166. But Node’s HTTPS implementation is noticeably slower than using HAProxy or Nginx

167. Where is SocketStream going next?

168. We’re in the process of getting SocketStream’s test coverage up

169. We’re also trying to close some ancient bugs

170. We also need better documentation

171. We’re giving the web site an overhaul

172. And we want to document how SocketStream’s internals function, to help build 0.4

173. but what about 0.4?

174. …0.4 is starting to look like these:

175. I promise you all, it’s coming in June 2014

176. Thank You

SocketStream

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