Node.js and Ruby

& Ruby

Saturday, April 17, 2010

@mbleigh


present.ly


What’s Node?


Evented I/O
for Javascript


Taking JS Beyond
the Browser


Runs on
Google’s V8


Supported By Node

• HTTP, TCP
• File I/O
• Redis, Mongo, SQL (DBSlayer)


Express: Node’s Sinatra

• RESTful DSL for Node webapps
• Cookies, sessions, caching, etc.
• expressjs.com


require.paths.unshift('path/to/express/lib')
require('express')

get('/', function(){
this.redirect('/hello/world')
})

get('/hello/world', function(){
return 'Hello World'
})

run()


Why Node?


Generally Speedy


> summary(node1$ttime)
Min. 1st Qu. Median Mean 3rd Qu. Max.
0.0000 0.0000 1.0000 0.7437 1.0000 106.0000

> summary(thin1$ttime)
0.000 1.000 1.000 1.122 1.000 74.000

> summary(narwhal1$ttime)
15.00 22.00 23.00 23.74 24.00 88.00

> summary(v8cgi1$ttime)
12.00 13.00 13.00 14.49 18.00 39.00

four.livejournal.com/1019177.html


Great at
Concurrency


Asynchronous
Everything


bit.ly/nodejs-fstream
function upload_file(req, res) {
req.setBodyEncoding('binary');

var stream = new multipart.Stream(req);
stream.addListener('part', function(part) {
part.addListener('body', function(chunk) {
var progress = (stream.bytesReceived / stream.bytesTotal *
100).toFixed(2);
var mb = (stream.bytesTotal / 1024 / 1024).toFixed(1);

sys.print("Uploading "+mb+"mb ("+progress+"%)015");

// chunk could be appended to a file if the uploaded file needs to
be saved
});
});
stream.addListener('complete', function() {
res.sendHeader(200, {'Content-Type': 'text/plain'});
res.sendBody('Thanks for playing!');
res.finish();
sys.puts("n=> Done");
});
}


Javascript is
great for this.


Browser and server,
together at last


Why Ruby?


Are you at the
right conf?


When to Node


Real-Time
Applications


WebSockets

• Persistent server connections
• Part of HTML5
• True real-time for web apps
• Deprecate to Flash Sockets

Why Real-Time?

• Better on your server
• Better for your user
• You need more buzzwords


Why JS for WebSockets?

• You already write your client
interaction code in Javascript
• Just an extension of that
• Same interface throughout

Hazards of a
Young Tool


node.websocket.js

• Framework-like approach
• Includes fun examples
• Node version headaches
• github.com/guille/node.websocket.js/


Socket.IO

• Multi-transport socket for Node
• Comes with client JS library
• For production usage
• github.com/rosepad/socket.io-node


node.ws.js
• Minimal Node WebSocket server
• Talk to your browser clients
• Javascript all the way down
• Mostly for experimentation
• github.com/ncr/node.ws.js

How can we
actually use it?


Redis is the Bridge

• Super-fast, super-awesome
• PUBSUB = WIN!
• Swiss-army knife for your app.


Example

• Twitter-esque status streams
• Want to update web interface in
real time
• Rails, Node, Redis, and Chrome

The Ruby Code


class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :token_authenticatable, :lockable and :timeoutable
devise :database_authenticatable, :registerable, :rememberable, :validatable

# Setup accessible (or protected) attributes for your model
attr_accessible :email, :password, :password_confirmation

def follow(other_user)
Red.sadd "user:#{other_user.id}:followers", self.id
Red.sadd "user:#{self.id}:follows", other_user.id
end

def follower_ids
Red.smembers "user:#{self.id}:followers"
end

def follow_ids
Red.smembers "user:#{self.id}:follows"
end

def update(text)
(follower_ids + [self.id]).each do |uid|
Red.lpush "user:#{uid}:timeline", text
Red.lpush "user:#{uid}:updates", text
Red.publish "user:#{uid}:timeline", text
end
end
end


def update(text)
(follower_ids + [self.id]).each do |uid|
Red.lpush "user:#{uid}:timeline", text
Red.lpush "user:#{uid}:updates", text
Red.publish "user:#{uid}:timeline", text
end
end


The Node Code


ws.createServer(function (websocket) {
var user_id = null;
var websocket = websocket;

websocket.addListener("connect", function (resource) {
user_id = resource.match(/timeline/([0-9]+)$/i)[1]
clients[user_id] = websocket;
}).addListener("close", function() {
sys.debug("User " + user_id + " disconnected.")
});
}).listen(8080);


pubsub.stream.addListener('connect', function() {
pubsub.subscribeTo("user:*:timeline", function(channel, data) {
var uid = channel.toString().split(':')[1];

if (clients[uid]) {
sys.debug("Writing " + data + " to " + uid)
clients[uid].write(data);
} else {
sys.debug("User " + clients[uid] + " is not connected.");
}
});
});


The Browser Code


if ("WebSocket" in window) {
var ws = new WebSocket("ws://127.0.0.1:8080/timeline/" +
current_user);

ws.onmessage = function(evt) {
$('ul.timeline').prepend("<li>" + evt.data + "</li>");
}
}


How else can we
use Node?


Asynchronous
Applications


Push APIs

• Want to notify API subscribers in
real-time
• Utilize Webhooks
• Example: GitHub’s Service Hooks

File Transcoding


Online Gaming


Ephemeral
Peer-to-Peer


Wrapping up...


Tip of the Iceberg

• Node’s libraries and use cases
are expanding rapidly
• Async means thinking differently
• Still at the early stages

howtonode.org


Node for Ruby?


EventMachine


Cramp


Use what feels right.


I don’t know
the half of it.


Questions?


Node.js and Ruby

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