Node.js Introduction

Agenda

What's Node
Node Web development
Who use Node

What's Node

Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.

Node VS Java platform

Language
Platform
Frameworks & Tools

Talk is cheap. Show me the code.
- Linus Torvalds

Hello, Server side javascript


//load third party module 'colors'.
var colors = require('colors');

//print out 'Hello Node.js' with colorized.
console.log("Hello Node.js".rainbow);

Chrome Javascript runtime - V8
API for server side
NPM

Hello, Asynchronous I/O Programming

$.ajax({
  url: 'http://www.claudejiang.com/echo',
  data: {param1: 'claude'},
  success: function(data){
    ...
  }
});

var fs = require('fs');

fs.readFile('text.txt', {encoding: 'UTF-8'}, function(err, data){
    if(err) throw err;
    console.log(data);
});
console.log('end.');

Asynchronous I/O APIs
Asynchronous Programming
Node style callback

Hello, Buffer/Stream/Event Emitter


var fs = require('fs');

var rs = fs.createReadStream(__filename);
rs.on('data', function(data){
  // console.log(data);
  console.log(data.toString());
});
rs.on('end', function(){
  console.log('end');
});
// rs.pipe(process.stdout);

Use Event(Sub/Pub) for Async IO
Buffer
Stream/pipe
Unix/Linux philosophy

Hello, TCP Programming


// load net module
var net = require('net');

// create a tcp server
var server = net.createServer(function (socket) {
  socket.on('data', function(data){
    socket.pipe(socket);
  });
});

// bind to port 7000 on localhost
server.listen(7000, "localhost");

console.log("TCP server listening on port 7000 at localhost.");

Hello, Web Programming


var http = require('http');

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(1337, '127.0.0.1');

console.log('Server running at http://127.0.0.1:1337/');

Hello DIRTy, Socket.io Programming


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);
  });
});


<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>

data-intensive real-time applications
chat/communication/stream/mongodb/proxy

Technique

JavaScript
Asynchronous I/O Programming
NPM

JavaScript

Performance - V8
CommonJS
Multi-paradigm programming
Asynchronize friendly
Atwood's law

Atwood's law

Any application that can be written in JavaScript, will eventually be written in JavaScript.

Linux VM: jsLinux
Emulator: GameBoy emulator
Cloud IDE: Nitrous Cloud9 IDE
Testing: Browserling PhantomJS
Client Dev: Node-webkit
Mobile Dev: Phonegap
Game Dev: Pomelo WebGL asm.js
Hardware: Tessel

Asynchronize I/O Programming

Why non-blocking io
Event Loop
Asynchronize Programming

Why non-blocking io

Synchronize block: M+N
Asynchronize non-block: Max(M,N)

Synchronize block


var fs = require('fs');
var path = require('path');

var files = fs.readdirSync('.'); // cpu wait
files.forEach(function(file){
  var stat = fs.statSync(file); // cpu wait
  if(stat.isFile()){
    var str = fs.readFileSync(file, {encoding: 'utf8'}); // cpu wait
    console.log(file + ":" + str.length);
  }
});

CPU浪费在等待IO上(M+N)

Asynchronize non-block


var fs = require('fs');
var path = require('path');

fs.readdir('.', function(err, files){
    if(err) return console.log(err);
    files.forEach(function(file){
        fs.stat(file, function(err, stat){
            if(stat.isFile()){
                fs.readFile(file, {encoding: 'utf8'}, function(err, str){
                    console.log(file + ":" + str.length);
                });
            }
        });
    });
});