Presentation of websockets usage in nodeJS, in the jsuc3m study group.

1. Jugando con
websockets en
Israel Gutiérrez

2. NodeJS
• Server side JavaScript
• Platform built over Chrome’s v8
• Event driven (asynchronous)
• Applications
• Data-intensive (efficiency)
• Real-time (websockets)

3. NodeJS architecture

4. npm
• node package manager
• express (routing)
• socket.io (websockets)
• mongo (database drivers)
• ...

5. Application stack
• HTTP server (or TCP-socket or
websockets)
• Router
• Request handlers
• Handle data received
• View logic

6. HTTP server
var http = require("http");
http.createServer(function(request, response) {
response.writeHead(200, {"Content-Type": "text/plain"});
response.write("Hello World");
response.end();
}).listen(8888);

7. TCP server
var net = require('net');
var server = net.createServer(function (socket) {
socket.write('Echo serverrn');
socket.pipe(socket);
});
server.listen(1337, '127.0.0.1');

8. Modules
server.js
var http = require("http");
function start() {
function onRequest(request, response) {
console.log("Request received.");
response.writeHead(200, {"Content-Type": "text/plain"});
response.write("Hello World");
response.end();
}
http.createServer(onRequest).listen(8888);
console.log("Server has started.");
}
exports.start = start;
index.js
var server = require("./server");
server.start();

9. Router and handlers
• You can program the routes based on
request.url
var server = require("./server");
var router = require("./router");
var requestHandlers = require("./requestHandlers");
var handle = {}
handle["/"] = requestHandlers.start;
handle["/start"] = requestHandlers.start;
handle["/upload"] = requestHandlers.upload;
server.start(router.route, handle);
• I recommend using express (Sinatra like)

10. Templating
• ejs
• underscore
• jade
• ...

11. Websockets
• Canal de comunicación full duplex
(bidireccional y a la vez) sobre TCP
• No hay cabeceras HTTP! (menos
overhead)
• Aplicaciones que requieren interacciones
en tiempo real
• URL tipo ws://

12. socket.io
• Websockets library
• Fallbacks
• Flash
• AJAX long polling
• AJAX multipart streaming
• Forever iframe
• JSONP polling

13. socket.io support
Desktop
• Internet Explorer 5.5+
• Safari 3+
• Google Chrome 4+
• Firefox 3+
• Opera 10.61+
Mobile
• iPhone Safari
• iPad Safari
• Android WebKit
• WebOs WebKit

14. socket.io example
Server
var io = require('socket.io').listen(80);
io.sockets.on('connection', function (socket) {
socket.emit('news', { hello: 'world' });
socket.on('my other event', function (data) {
console.log(data);
});
});
Client
<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect('http://localhost');
socket.on('news', function (data) {
console.log(data);
socket.emit('my other event', { my: 'data' });
});
</script>

15. References
• http://nodejs.org/
• http://www.nodebeginner.org/
• https://npmjs.org/
• http://socket.io/
• http://www.nodecloud.org/

16. Let’s do some fucking
code!!!