VN-INFO meetup 16/07/2014 at Officience, Paris Son NGUYEN KIM (@nguyenkims)

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.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.

PLAN

1. Introduction

2. Event-driven programming

3. JS becomes now a normal language

4. JS becomes now a wonderful language for the web !

5. Drawbacks

I. INTRODUCTION Motivation

History

Main concept

NODE.JS IS USED BY BIGGEST COMPANIES IN VARIOUS DOMAINS

MOTIVATION

HISTORY

• Created in 2009 by Ryan Dahl

• Sponsored by Joyent

Image copied from http://blog.newrelic.com/2012/07/11/recap-of-nodeconf-2012/

event-driven programming !

MAIN CONCEPT

Image copied from http://kunkle.org/nodejs-explained-pres/#/conceptually-simple

II. EVENT-DRIVEN PROGRAMMING !

Single thread, multi-threading Event-driven programming definition

Why JS is good choice to do event-driven programming ?

SINGLE-THREAD

I/O Read file

Main thread

SINGLE-THREAD

I/O Read file

Main thread

Blocking ...

MULTI-THREAD

I/O Read file

I/O Query DB

Main thread

Thread 1

Thread 2

MULTI-THREAD

I/O Read file

I/O Query DB

Main thread

Thread 1

Thread 2

Manage concurrency : lock everywhere !

Debug / Write / Test

EVENT-DRIVEN PROGRAMMING DEFINITION

Flow determined by events !

result = db.query(‘select * from facebook.users’) f(result)

!!

Flow determined by events !

result = db.query(‘select * from facebook.users’) f(result)

!db.query(‘select * from facebook.users’, f)

!

EVENT-DRIVEN PROGRAMMING DEFINITION

EVENT LOOPImage copied from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/EventLoop

EVENT LOOPImage copied from http://www.aaronstannard.com/post/2011/12/14/Intro-to-NodeJS-for-NET-Developers.aspx

EVENT LOOPImage copied from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/EventLoop

2 interesting properties :

There is at most one event handler running at any given time.

Any event handler will run to completion without being interrupted.

WHY JS ?

• No mix of blocking and non-blocking IO

• Closure : no need to pass context around.

• First-class function : pass function as argument

III. JS becomes now a normal language

• Interactive mode

• Launch script without passing by html

• Read file, connect to DB ...

IV. A wonderful language for the web !

• Static web server with several lines of code

• NPM

• Lot of modules to work with the web: cookie, tcp, parse json ...

• Perfect match for client-side JS (ex: angularJS)

• Horizontal scale

V. Drawbacks

• Limited set of library : mp3, png ...

• Not hit 1.0 yet, still 0.10 (same as Hadoop with version 0.23 ...)

• IDE, debugger ... very primitive

• Javascript inherent difficulties ?

THANKS YOU !