Full duplex data exchange between client and server without waiting for request-response cycle and with a custom event

1109.js

var net = require('net')
const DELIM = '*'

const server = net.createServer((s) => {
  s.setNoDelay(true)
  s.on('data', (d) => {
    if (d.includes(DELIM)) {
      var index = d.indexOf(DELIM, 0)
      while (d.length) {
        const piece = d.slice(0, index) 
        s.write(piece.toString().toUpperCase())
        s.write(DELIM)
        d = d.slice(index + 1)
        index = d.indexOf(DELIM, 0)
      }
    }
  })
})

server.listen(() => {
  const c = net.createConnection({ port: server.address().port}, () => {
  })
  c.setNoDelay(true)
  c.on('data', (d) => {
    if (d.includes(DELIM)) {
      var index = d.indexOf(DELIM, 0)
      while (d.length) {
        c.emit('response',  d.slice(0, index))
        d = d.slice(index + 1)
        index = d.indexOf(DELIM, 0)
      }
    }
  })
  c.on('response', (d) => {
    console.log(`output: ${d.toString()}`)
  })
   setInterval(() => {
    for (var i=0; i< 16; i++) {
	const data = getModbus()
      console.log('input: ' + data.toString())
      c.write(data)
      c.write(DELIM)
     }
  }, 100)
})

function getModbus() {
  const buf = Buffer.alloc(10)
  for (var i = 0; i< 10; i++)
    buf[i] = [(97 + Math.round((Math.random() * 26)))]
  return buf;
}