• open-source, cross-platform, MIT license
• asynchronous, event driven
• event loop as a language construct not library
• shell/repl (read-eval-print-loop)
• npm - package manager
• other: Twisted (python), Vert.x (Java, Ruby, Scala, Clojure...)

History

• 2009 - originally written by Ryan Dahl
• 2011 - added npm and support for Windows
• 2014 - Fedor Indutny started io.js, a fork of Node.js
• 2015 - Node.js v0.12 and io.js v3.3 merged back into Node v4.0

Node.js Foundation

• Node.js is a trademark of Joyent, Inc. (high-performance cloud computing)
• Foundation corporate members: IBM, Intel, Microsoft, RedHat, PayPal, Joyent...
• ~300 active contributors (~900 in total)

Architecture

Architecture

• core written in C, C++
• single main thread, non-blocking I/O calls
• no cost of thread context switching
• thread pool for parallel tasks, when done main thread wakes up and executes the registered callback
• registered within operating system, operating system issues a callback on connection

Google’s V8 JavaScript engine

• compiles JavaScript into native code
• garbage collector
• optimizer
• re-optimizer (at runtime)
  • based on heuristics of the code's execution profile
  • inline expansion
  • inline caching
  • copy elision

libuv - multi-platform asynchronous I/O

• developed for use by Node.js, also used by others
• event loop
• asynchronous TCP/UDP sockets and DNS resolution
• asynchronous file system operations
• child processes
• thread pool

Miscellaneous

• possibility to write C++ addons
• debugging - IDE ot Chrome Dev Tools
• build in modules: fs, os, path, querystring, zlib, vm, crypto
• globals: console, require, process, module, exports, global

Code

Frameworks

• Express.js, Hapi.js, Koa.js - minimalist
• Socket.io - for real-time apps
• Sails, Derby - MVC frameworks
• Meteor - pure magic

Basics

var http = require('http');

var handleRequest  = function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hit: ' + req.url);
};

http.createServer(handleRequest).listen(3000, function () {
    console.log("Server listening on: http://localhost:3000");
});

Express

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

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

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

app.listen(3000, function () {
    console.log("Server listening on: http://localhost:3000");
});

Express - static content

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

app.use('/static', express.static(__dirname + 'public'));

app.listen(3000, function () {
    console.log("Server listening on: http://localhost:3000");
});

Express - jade templates

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

app.set('views', __dirname + '/views');
app.set('view engine', 'jade');

app.get('/', function(req, res){
    res.render("index", {message: 'Hello world!'});
});

app.listen(3000, function () {
    console.log("Server listening on: http://localhost:3000");
});

html
  head
    title title
  body
    h1= message

Live demo

npm install express-generator -g
express myapp

Forever

npm install forever -g
forever start app.js

NODE_ENV=production forever start -l forever.log -o out.log -e err.log app.js

forever list

forever stop app.js

forever stopall

Scaling

Scaling - cluster

const cluster = require('cluster');
const http = require('http');
const numberOfCpus = require('os').cpus().length;

function spawnMaster() {
    for (var i = 0; i < numberOfCpus; i++) {
        cluster.fork();
    }
    cluster.on('exit', (worker, code, signal) => {
        console.log(`worker ${worker.process.pid} died`);
    });
}

function spawnFork() {
    // Workers can share any TCP connection, in this case it is an HTTP server
    http.createServer((req, res) => {
        res.writeHead(200);
        res.end('hello world\n');
    }).listen(8000);
}

cluster.isMaster ? spawnMaster() : spawnFork();

Scaling - forks

Future

• long-term support plan (LTS)
• Microsoft Chakra Core engine usage
• involvement of large companies like Intel, Microsoft and IBM
• IoT, Mobile