Node.js

Description

Node.js est un canevas événementiel pour réaliser des applications serveur en Javascript. L'ensemble des événements est traité par une seule thread: Node.js privilégie les appels non bloquants. Node.js facilite le push (serveur --> client Web)

Cours

• Formation Valtech : http://public.valtech-training.fr/DekNOD/slideshow/dist/#1

Lancement

Aide

node --help

Interactif

node

En ligne

node -p -e "Boolean(process.stdout.isTTY)"

En argument (process.argv[1])

node httpserver.js 8080

API

Des nombreuses bibliothèques sont disponibles : Assertion Testing, Buffer, C/C++ Addons, Child Processes, Cluster, Crypto, Debugger, DNS, Domain, Events, File System, Globals, HTTP, HTTPS, Modules, Net, OS, Path, Process, Punycode, Query Strings, Readline, REPL, STDIO, Stream, String Decoder, Timers, TLS/SSL, TTY, UDP/Datagram, URL, Utilities, VM, ZLIB

Canevas

Des nombreux canevas sont construits sur Node.js

• ql.io
• ...

Registre

Plusieurs modules sont catalogués depuis le registre https://npmjs.org/ et installables avec npm (Node Package Manager)

# Voir les packages disponibles 
npm ls

# Voir les packages installés
npm ls installed

# Rechercher un package
npm search duino

# Installer un package pour le contrôle d'une carte Arduino
npm install duino

# Installer un package
npm publish mypackage

Modules pour les projets AIR

• node-serialport access serial ports for reading and writing
• duino A framework for working with Arduinos in node.js
• firmata A Node library to interact with an Arduino running the firmata protocol.

Exemples

Lancement

Aide

node --help

Interactif

node

En ligne

node -p -e "Boolean(process.stdout.isTTY)"

En argument (process.argv[1])

node httpserver.js 8080

HTTP script

var port = process.argv[2];

var http = require("http");

function onRequest(request, response) {
  console.log("Receiving a request");
  response.writeHead(200, {"Content-Type": "text/plain"});
  response.write("Hello World");
  response.end();
}

http.createServer(onRequest).listen(port);
console.log("Server started. ^C to kill it");

node hello.js 8888

Express

var express = require('express');
var app = express();
app.get('/hello.txt', function(req, res){
  res.send('Hello World');
});
app.listen(3000);

node install express
node express.js 3000

start http://localhost:3000/hello.txt

UDP Datagrams

var dgram = require("dgram");

var server = dgram.createSocket("udp4");

server.on("message", function (msg, rinfo) {
  console.log("server got: " + msg + " from " +
    rinfo.address + ":" + rinfo.port);
});

server.on("listening", function () {
  var address = server.address();
  console.log("server listening " +
      address.address + ":" + address.port);
});

server.bind(41234);
// server listening 0.0.0.0:41234

node dgram.js

Crypto: SHA1 Hashing

var filename = process.argv[2];
var crypto = require('crypto');
var fs = require('fs');

var shasum = crypto.createHash('sha1');

var s = fs.ReadStream(filename);
s.on('data', function(d) {
  shasum.update(d);
});

s.on('end', function() {
  var d = shasum.digest('hex');
  console.log(d + '  ' + filename);
});

node hash.js hash.js

TTY

process.stdout.on('resize', function() {
  console.log('screen size has changed!');
  console.log(process.stdout.columns + 'x' + process.stdout.rows);
});

node resize.js

$ node -p -e "Boolean(process.stdout.isTTY)"
true
$ node -p -e "Boolean(process.stdout.isTTY)" | cat
false

Cluster

var port = process.argv[2];
var cluster = require('cluster');
var http = require('http');
var numCPUs = require('os').cpus().length;

if (cluster.isMaster) {
  // Fork workers.
  for (var i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  cluster.on('exit', function(worker, code, signal) {
    console.log('worker ' + worker.process.pid + ' died');
  });
} else {
  // Workers can share any TCP connection
  // In this case its a HTTP server
  http.createServer(function(req, res) {
    res.writeHead(200);
    res.end("hello world\n");
  }).listen(port);
}

node httpcluster.js 8080

Serial GPS

var SerialPort = require("serialport").SerialPort;
var util = require("util"), repl = require("repl");

var port = process.argv[2];
var baudrate = process.argv[3];


if (!port) {
  console.log("You must specify a serial port location of your NMEA GPS receiver.");
} else {
  if (!baudrate) {
    baudrate = 4800;
  }

  var serial_port = new SerialPort(port, {baudrate: baudrate});
  
  serial_port.on("data", function (data) {
    util.puts("data: "+data);
  })
  serial_port.on("error", function (msg) {
    util.puts("error: "+msg);
  })
  repl.start("=>")
  
//serial_port.close();
}

npm install serialport
node serialgps.js

Simple Arduino Test

// arduino-ldr-read.ino from https://github.com/voodootikigod/node-serialport/blob/master/tests/arduino-ldr-read.pde
int sensorPin = A0;    // select the input pin for the potentiometer
int ledPin = 13;      // select the pin for the LED
int sensorValue = 0;  // variable to store the value coming from the sensor

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  sensorValue = analogRead(sensorPin);
  Serial.println(sensorValue);
  digitalWrite(ledPin, HIGH);
  delay(sensorValue);
  digitalWrite(ledPin, LOW);
  delay(sensorValue);
}

// From https://github.com/voodootikigod/node-serialport/blob/master/tests/arduino-ldr-read.js
// For use with Arduino LDR
// Upload arduino-ldr-read.ino to Arduino apparatus via Arduino IDE

var port = process.argv[2];

var sys = require("sys"),
		repl = require("repl"),
		serialPort = require("serialport").SerialPort,

		//	Required
		defaults = {
			baudrate: 9600
		},
		//	Create new serialport pointer
		serial = new serialPort(port , defaults);


//	Add data read event listener
serial.on( "data", function( data ) {

	var output;

	//	Coerce data into a number
	data = +data;

	//	If data is worth reading and processing
	if ( data && data > 1 ) {

		//	Create a new Array() whose length equals data
		//	then join to create output visualization
		output = ( new Array(data) ).join( ">" );

		//	Print the data value along with visualization of data
		sys.puts( data + " " + output );
	}

});


serial.on( "error", function( msg ) {
	sys.puts("error: " + msg );
});


repl.start( "=>" );

npm install serialport
node arduino-ldr-read.js /dev/ttyACM0