Install Node.js 62017/09/23

	Install ServerSide JavaScript Environment Node.js 6 (LTS).
[1]	It's possible to install from CentOS SCLo Software Collections. It's OK to install it even if another version of Node.js is already installed because 6.x is located on another PATH.

# install from SCLo

[root@dlp ~]#

yum --enablerepo=centos-sclo-rh -y install rh-nodejs6

[2]	Packages from Software Collections are installed uder the /opt directory. To use it, Load environment variables like follows.

# load environment variables

[root@dlp ~]#

scl enable rh-nodejs6 bash

[root@dlp ~]#

node -v

v6.9.1

[root@dlp ~]#

which node

/opt/rh/rh-nodejs6/root/usr/bin/node

[3]	If you'd like to enable Node.js 6 automatically at login time, configure like follows.

[root@dlp ~]#

vi /etc/profile.d/rh-nodejs6.sh

# create new

#!/bin/bash

source /opt/rh/rh-nodejs6/enable
export X_SCLS="`scl enable rh-nodejs6 'echo $X_SCLS'`"

[4]	Create a test tool. It's possible to do it as a common user.

[cent@www ~]$

vi helloworld.js

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('listening on http://127.0.0.1:1337/');

# run server

[cent@www ~]$

node helloworld.js &

# verify (it's OK if following reply is back )

[cent@www ~]$

curl http://127.0.0.1:1337/

Hello World

[5]	Install Socket.IO and create a test apprication with using WebSocket.

[cent@www ~]$

npm install socket.io express

[cent@www ~]$

vi chat.js

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);

app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});

io.on('connection', function(socket){
  socket.on('chat message', function(msg){
    io.emit('chat message', msg);
  });
});

http.listen(1337, function(){
  console.log('listening on *:1337');
});

[cent@www ~]$

vi index.html

<!DOCTYPE html>
<html>
<head>
<title>WebSocket Chat</title>
</head>
<body>
<form action="">
<input id="sendmsg" autocomplete="off" /><button>Send</button>
</form>
<ul id="messages" style="list-style-type: decimal; font-size: 16px; font-family: Arial;"></ul>
<script src="/socket.io/socket.io.js"></script>
<script src="http://code.jquery.com/jquery.min.js"></script>
<script>
  var socket = io();
  $('form').submit(function(){
    socket.emit('chat message', $('#sendmsg').val());
    $('#sendmsg').val('');
    return false;
  });
  socket.on('chat message', function(msg){
    $('#messages').append($('<li style="margin-bottom: 5px;">').text(msg));
  });
</script>
</body>
</html>

[cent@www ~]$

node chat.js

listening on *:1337

Access to [http://(server's hostname or IP address):1337/] from a Client computer to make sure sample app works normally.

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