1. Node.JS and
WebSockets with Faye
Matjaž Lipuš
@MatjazL

2. Real-time web
The real-time web is a set of technologies and practices which
enable users to receive information as soon as it is published.
http://en.wikipedia.org/wiki/Real-time_web

3. Real-time web - Server
• Long, streaming connections
• Apache, IIS
• Node, nginx, Tornado, Thin, Netty

4. Real-time web - Client
• Fast, small, simple API
• Long polling, streaming, websockets
• socket.IO, Faye

5. NodeJS
• JavaScript bindings to system I/O
• Server-side JavaScript (Google’s V8)
• Most of Node is written in JavaScript
• Current v0.2.4
more: http://nodejs.org

6. NodeJS - non blocking I/O
• (almost) nothing blocks
• Similar to EventMachine and Twisted
 without "run()", simply enters event loop, like browser
• No function should direct perform I/O
• Stream everything; never force the buffering of data

7. NodeJS - non blocking I/O
puts("Enter your name: ");
var name = gets();
puts("Name: " + name);
puts("Enter your name: ");
gets(function (name) {
puts("Name: " + name);
});

8. NodeJS - One process and thread
• Event loop
 events
 callbacks
• Multi processes
 web workers API
 multi-node module

9. NodeJS - HTTP protocol
• Built for web
• Easy library and framework development
http.createServer(function(req, res) {
res.writeHead(200, {
"Content-Type": "text/plain"
});
res.end("Hello Worldn");
}).listen(8080);

10. NodeJS - JavaScript
• Anonymous functions, closures
• Only one callback at a time
• I/O through DOM event callbacks
• Javascript === evented programming

11. NodeJS - Modules
• CommonJS
• Built-in
 process, util, buffer
 fs, net, http
• Third part
 http://github.com/ry/node/wiki/modules
 npm package manager

12. NodeJS - Addons
• Glue to C and C++ libraries
extern "C" void init (Handle<Object> target)
• http://github.com/ry/node_postgres

13. NodeJS - In development
• API changes
• Unstable modules (SSL)
• Short release cycles

14. Faye
• Simple pub/sub messaging for the web
• Bayeux
more: http://faye.jcoglan.com

15. Faye - Concepts / patterns
• Deferrable
• Observable
• Extensible
• Timeouts
• Logging
• Set

16. Faye - Classes
• Server
• Connection
• Client
• Transport
 HttpTransport
 LocalTransport - in process
 WebSocket
 XHR - long polling
 JSONP - callback polling
• Channel
• Subscription

17. Faye - Adapters
• NodeAdapter
• RackAdapter
var server = new Faye.NodeAdapter({
mount: "/",
timeout: 60
});

18. Faye - Server
var Faye = require("faye"),
server = new Faye.NodeAdapter();
server.listen(8000);
server.getClient().publish("/email/new",{
text: "New email has arrived!",
});

19. Faye - Client
var client = new
Faye.Client("http://localhost:8000/bayeux");
client.subscribe("/messages",
function(message) {
alert("Got a message: " + message.text);
});
client.publish("/messages", {
text: "Can anyone hear me?"
});

20. Faye - Extensions
var serverAuth = {
incoming: function(message, callback) {
if (message.channel === "/meta/subscribe") {
checkAuth(message, function(authorized) {
if (!authorized) {
message.error = "Access denied";
}
callback(message);
});
} else {
callback(message);
}
}
};
server.addExtension(serverAuth);
server.removeExtension(serverAuth);

21. Links
• http://nodejs.org
• http://faye.jcoglan.com
• http://howtonode.org
• http://s3.amazonaws.com/four.livejournal/20091117/
jsconf.pdf
• http://nodejs.org/jsconf2010.pdf
• http://howtonode.org/step-of-conductor

22. Contact
Matjaž Lipuš
@MatjazL