Node.js

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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

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

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.

Déploiement sur PaaS

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

// udpreceiver.js <port>
var port = process.argv[2];

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(port);




// node udpsender.js <hostname ou ip address> <port>

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

var dgram = require("dgram");
var readline = require('readline');

var client = dgram.createSocket("udp4");
var rl = readline.createInterface(process.stdin,process.stdout);

rl.setPrompt('> ');
rl.prompt();

rl.on('line', function(line) {
  switch(line.trim()) {
    case 'exit':
      rl.close();
      break;
    default:
    
    var msg = {
  		payload: line,
  		timestamp: new Date(),
  		expires: "NEVER"
	};
    
    var message = new Buffer(JSON.stringify(msg));
    //if(message.length<=0) break;
	client.send(message, 0, message.length, port, host, function(err, bytes) {
	    console.log("message "+ message + " sent");
  		});
      break;
  }
  rl.prompt();
}).on('close', function() {
  console.log('Bye Bye!');
  process.exit(0);
});


Terminal 1 

npm install readline
node udpreceiver.js 5000


Terminal 2 

node udpsender.js localhost 5000

Terminal 3 

node udpsender.js 0.0.0.0 5000

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


REPL (Read-Eval-Print-Loop)

var net = require("net"),
    repl = require("repl");

connections = 0;

repl.start({
  prompt: "node via stdin> ",
  input: process.stdin,
  output: process.stdout
});

net.createServer(function (socket) {
  connections += 1;
  repl.start({
    prompt: "node via TCP socket> ",
    input: socket,
    output: socket
  }).on('exit', function() {
    connections -= 1;
    socket.end();
  });
}).listen(5001);



node repl.js

1+2+3+4+5



telnet localhost 5001

1+2+3+4+5

.help

.exit

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


Simple Arduino Test

Placez la patte du milieu d'un potentiomètre sur la pin analogique A0 (les pattes des bords sur GND et +5V). Téléversez l'exemple File > Examples > 01.Basics > AnalogReadSerial de l'IDE sur votre Arduino. 

// AnalogReadSerial.js <port>
var port = process.argv[2];
var serialport = require('serialport');

var port = new serialport.SerialPort(port, {
                baudrate: 9600,
                parser: serialport.parsers.readline('\r\n')});

port.on('data', function(line) {
    console.log(line);
});

npm install serialport
node AnalogReadSerial.js /dev/tty.usbmodemfa131

Arduino avec Firmata

Placez la patte du milieu d'un potentiomètre sur la pin analogique A0 (les pattes des bords sur GND et +5V). Téléversez l'exemple File > Examples > Firmata > StandardFirmata sur votre Arduino 

// testfirmata.js <port>
var port = process.argv[2];

var firmata = require('firmata');
var board = new firmata.Board(port,function(){
  //arduino is ready to communicate
  board.analogRead(0,function(data){
  	console.log(data);
  })
});  

npm install firmata
node testfirmata.js /dev/tty.usbmodemfa131

Voir https://github.com/jgautier/firmata


NMEA 0183 Parsing

var nmea = require('nmea')

var sentences = [
"$GPGSA,A,1,,,,,,,,,,,,,,,*1E",
"$GPGSV,3,1,12,29,75,266,39,05,48,047,,26,43,108,,15,35,157,*78",
"$GPGSV,3,2,12,21,30,292,,18,21,234,,02,18,093,,25,13,215,*7F",
"$GPGSV,3,3,12,30,11,308,,16,,333,,12,,191,,07,-4,033,*62",
"$GPRMC,085542.023,V,,,,,,,041211,,,N*45",
"$GPGGA,085543.023,,,,,0,00,,,M,0.0,M,,0000*58",
];

for (var i=0; i < s.length; i++) {
    console.log(nmea.parse(sentences[i]));
};



npm install nmea
node testnmea.js



// serialnmea.js <port>
var port = process.argv[2];
var serialport = require('serialport');
var nmea = require('nmea');

var port = new serialport.SerialPort(port, {
                baudrate: 4800,
                parser: serialport.parsers.readline('\r\n')});

port.on('data', function(line) {
    console.log(nmea.parse(line));
});

npm install nmea
node serialnmea.js /dev/cu.usbserial


see also https://npmjs.org/package/coordinator

NFC RFID Readers

See: 

var HID = require('node-hid');
console.log(HID.devices());

npm install node-hid
node listhid.js
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