Resources

Node Homepage

http://nodejs.org

Github

https://github.com/joyent/node

Node API documentation (v0.4.11)

http://nodejs.org/docs/v0.4.11/api

Available Modules

https://github.com/joyent/node/wiki/modules

Tutorials

http://howtonode.org/

http://nodetuts.com/tutorials

http://www.nodebeginner.org/

http://www.google.com :)

Creating A Module

Module

var counter = 0;

exports.counter = function() {
  return counter++;
};

Using the Module

var mymodule = require('./mymodule');

setInterval(function() {
    console.log(mymodule.counter())
  }, 1000);

Building a Simple Web App - Step 5

Install jsdom

npm install jsdom

Install jquery

npm install jquery

Alter Hello World file to do server side magic

var jsdom = require('jsdom');
var jquery = require('jquery');
var express = require('express');

var app = express.createServer();

app.set('view engine', 'jade');

app.configure(function() {
  app.use(express.static(__dirname + '/static'));
});

app.get('/', function(req, res) {
  res.render('index', {title: 'Express/Jade Example'});  
});

app.get('/:dir', function(req, res) {
  var dir = req.params.dir.toLowerCase();
  res.render(dir, {title: dir + ' page'}, function(err, contents){
    var document = jsdom.jsdom(contents);
    var window = document.createWindow();
    var $ = jquery.create(window);

    $('#nav li a').each(function(index) {
      if($(this).text().toLowerCase() == dir) {
    $(this).addClass('current');
      } else {
    $(this).removeClass('current');
      }
    });

    res.send(window.document.innerHTML);

  });
});

app.listen(3000);
console.log('Server is running on localhost:3000');

Building a Simple Web App - Step 4

Add navigation to layout.jade

ul#nav
      li 
        a(href='/', class='current') Home
      li
        a(href='/summary') Summary
      li 
        a(href='/map') Map

Add nav styles to styles.css

#nav {  
  margin: 0;
  padding: 0;
}

#nav li {
  display: inline;
}

#nav a:link,
#nav a:visited {
  color: #000;
  background: #b2b580;
  padding:20px 40px 4px 10px;
  text-decoration: none;
}

#nav a.current {
  color: #fff;
}

Create summary.jade and map.jade in Views folder

Create route for new summary and map pages in express

app.get('/:dir', function(req, res) {
  res.render(req.params.dir, {title: req.params.dir + ' page'});
});

Building a Simple Web App - Step 3

Create A Layout - layout.jade in Views folder

html
  head
  title #{title}
  body    
    !{body}
    div#myDiv Hello from layout

Alter index.jade

h1 Hello World From index.jade

Create static file - styles.css

#myDiv {
  font-size: 18px;
  color: red;
}

Link to css file in layout.jade

link(href='/css/styles.css', rel='stylesheet', type='text/css')

Tell express to serve static files

app.configure(function() {
  app.use(express.static(__dirname + '/static'));
});

Building a Simple Web App - Step 2

Install Jade - View Template Engine

npm install jade

Create index.jade in Views folder

html
  head
  title #{title}
  body
    h1 Hello World

Modify your Hello World file

var express = require('express');

var app = express.createServer();

app.get('/', function(req, res) {
  res.render('index.jade', {layout: false, title: 'Express/Jade Example'});  
});

app.listen(3000);
console.log('Server is running on localhost:3000');

Building a Simple Web App - Step 1

Install Express

npm install express

Create Hello World Server

var express = require('express');

var app = express.createServer();

app.get('/', function(req, res) {
    res.send('Hello World!');
});

app.listen(3000);
console.log('Server running on localhost:3000');

Debugging

Debugging with node-inspector

1. Install node-inspector
   
   

   npm install -g node-inspector
   

2. Enable debugging on the program you want to debug:
   
   
   

   node --debug HelloWorldServer.js
   

   
   
3. Launch node inspector:
   
   
   

   node-inspector &
   

   
   
4. Open a WebKit browser ie. Chrome to http://127.0.0.1:8080/debug?port=5858
5. Click on the Scripts tab and choose your js file from the list
6. Happy Stepping Over, Stepping Into, Stepping Out!

Chat Web Server

This application will use a new module found on https://github.com/joyent/node/wiki/modules.

npm install faye

The faye module is built on the bayeux protocol and passes messages to all connected clients. The server code will handle two endpoints - the faye endpoint on port 8000 and a web server on port 9000 to server up the user's page.

application.js:

var express = require('express');
var faye = require('faye');

// Create the faye server
var bayeux = new faye.NodeAdapter({mount: '/faye', timeout: 45});
bayeux.listen(8000);

// Create the web server
var server = express.createServer();
server.configure(function() {
    server.use(express.static(__dirname + '/public'));
});
server.listen(9000);

console.log('Web Server listening on 9000, Bayeux on 8000');

The html page has a simple form to allow the user to input a message and some javascript to hook up the events and publish the messages.

public/index.html:

<html>
<head>
    <script type="text/javascript" src="http://localhost:8000/faye.js"></script> 
</head>
<body>

    <div style="width:800px; margin:5px; padding:5px;">
        <input id="message" type="text" size="70"></input>
        <input id="post" type="submit" value="Post Message"></input>
        <ul id="messages" style="border:1px solid Silver; padding:5px 0;"></ul>
    </div>

    <script type="text/javascript">

        // Create a "unique" id for this client (hack)
        var id = Math.floor(Math.random() * 100000);

        // Create the client and connect to the server
        var client = new Faye.Client('http://localhost:8000/faye');
        client.connect();

        // Subscribe to the chat channel to receive messages
        client.subscribe('/faye/chat', function(message) {
            var messages = document.getElementById('messages');
            messages.innerHTML = '<li style="margin-left:20px;">' +
                     message.text + '</li>' + messages.innerHTML;
        });

        // Handle the button click to allow users to post messages
        var button = document.getElementById('post');
        button.onclick = function() {
            var message = document.getElementById('message');
            if (message.value != '') {
                   client.publish('/faye/chat', { text: id + ': ' + 
                           message.value })
                   message.value = '';
                   message.focus();
            }
            return false;
        }

    </script>

</body>
</html>

A huge advantage of node is the ability to share code between applications in the browser and applications in the server. Let's add a server "bot" that will respond to chat messages. We do this with the same code the browser does:

// Create a client on the server
// Code is nearly identical to browser
bayeux.getClient().subscribe('/faye/chat', function(message) {
    if (message.text.indexOf('admin:pid') > -1) {
        bayeux.getClient().publish('/faye/chat', 
            { text:'admin pid is ' + process.pid }
        );
    }
});

Chat Server

var net = require('net');
var sockets = [];
net.createServer(function(socket) {
    sockets.push(socket);

    socket.on('data', function(data) {
        console.log(socket.remoteAddress + ' - ' + data);
        for(var i = 0; i < sockets.length; i++) {
            if (sockets[i] != socket)
                sockets[i].write(data); 
        }
    });

    socket.on('end', function() {
        sockets.splice(sockets.indexOf(socket), 1);
    })

}).listen(9000, 'localhost');

What's going on here?

• Line 2 creates an array for us to store a reference to the sockets
• Line 3 creates the socket server where we pass in our callback function
• Line 4 adds the new socket to our array
• Lines 5-11 writes the incoming data to each socket in our listen
• Lines 12-14 removes any dead sockets - why can we do this without locking?

Hello World - Web Server

var http = require('http');
var server = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hello World');
});
server.listen(4567);
console.log('Server is running at http://localhost:4567');

Lets take this example a bit further and add a setTimeout function to simulate a long running database query. Now each web request will take 1 second to complete.

var http = require('http');
var server = http.createServer(function(request, response) {
    response.writeHead(200, {'Content-Type':'text/plain'});
        setTimeout(function() {
            response.end('Hello World');
    }, 1000);
});
server.listen(4567);
console.log('Server is running at http://locahost:4567');

Start the server and run apache bench against it. How long do the following take to finish?

ab -n 10 -c 1 http://localhost:4567/ (1 user sending 10 requests)

ab -n 100 -c 10 http://localhost:4567/ (10 users sending 10 requests)

ab -n 1000 -c 100 http://localhost:4567/ (100 users sending 10 requests)

How would would you do this in Ruby/Python/.Net/Java? Would you get similar response times?

Hello World!

1. Type the following into a file called HelloWorld.js
   
   
   

   setTimeout(
     function() { 
       console.log('World'); 
     }, 2000);
   
   console.log('Hello');
   

   
   
2. Launch your program in Node and watch in amazement:
   
   
   

   node HelloWorld.js
   

   
   

Installing Node

Official wiki

Installation Guide

Installing on Ubuntu/Linux

#prerequisites on ubuntu

sudo apt-get install git

sudo apt-get install libssl-dev

#download node and build

sudo git clone http://github.com/joyent/node.git

cd node

sudo git checkout v0.4.10

sudo ./configure

sudo make

sudo make install

#check if it worked
node -v

Install on Windows

Don't!

A Windows pre-built binary has been released but it is unstable. You can download it here: http://nodejs.org/dist/v0.5.4/node.exe

We would suggest running a Linux VM to play around with node.

NPM - Node Package Manager

Unix install

curl http://npmjs.org/install.sh | sh

Or

sudo git clone http://github.com/isaacs/npm.git

cd npm

sudo make install

Did it work?

node -v

npm -v

What Is Node.js?

History

1. Official name is "Node". Unofficial name is "Node.js"
2. Written by Ryan Dahl in 2009
3. Dahl is employed by Joyent, Node's main sponsor (http://github.com/joyent/node)

What is it?

1. server-side JavaScript environment
2. runs on top of Google's V8 JavaScript engine (engine in Chrome)
3. event-driven I/O - not just web servers, but also things like sockets

Why is it useful?

1. it's javascript!
2. on the server!
3. less resource requirement on the server - does not spawn a new thread for every request. Instead, it allocates resources as needed.
4. does not directly block for I/O calls

Who's using it?

1. Yammer
2. Github
3. 37Signals
4. Palm/HP (webOs)
5. Rdio
6. https://github.com/joyent/node/wiki/Projects,-Applications,-and-Companies-Using-Node