index.js

const http = require('http');
const url = require('url')
const os = require('os');
const cluster = require('cluster')
var StringDecoder = require('string_decoder').StringDecoder
var decoder = new StringDecoder('utf-8')



const startServer = function () {
  
    const server = http.createServer(function (req, res) {
        var parsedUrl = url.parse(req.url, true);
        res.setHeader('Content-Type', 'application/json')
        if (parsedUrl.pathname === '/hello') {
            res.writeHead(400)
            req.on('data', function (data) {
                var yourMessage = '';
                yourMessage = decoder.write(data);
                res.end(JSON.stringify({ greeting: "Hello!", message: yourMessage }))
            })
            req.on('end', function () {
                res.end(JSON.stringify({ greeting: "Hello!" }))
            })
        } else {
            res.writeHead(200)
            res.end(JSON.stringify({ youUsed: 'other route' }))
        }
    })
    server.listen(3000, function () {
        console.log('server is listening on port 3000')
    });
}

const init = function (callback) {
    if (cluster.isMaster) {
        for (var i = 0; i < os.cpus().length; i++) {
            cluster.fork()
        }
      
    }else{
        startServer()
    }
   
    callback();
}



if(require.main===module){
    init(function(){});
}