Node.JS and WebSockets with Faye

Node.JS andWebSocketswithFaye
Matjaž Lipuš
@MatjazL

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

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

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

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

NodeJS - nonblocking 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

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

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

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("HelloWorld ");
}).listen(8080);

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

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

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

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

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

Faye- Concepts / patterns
Deferrable
Observable
Extensible
Timeouts
Logging
Set

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

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

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

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?"
});

Faye - Extensions
varserverAuth = {
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);

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

Contact
Matjaž Lipuš
@MatjazL

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Node.JS and WebSockets with Faye

by Matjaž Lipuš on Oct 30, 2010

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