How can a TCP/IP server write data on a HTTP server?

Here is my tcp/ip server that listens to IoT sensors sending it data:

const net = require('net')

const server = net.createServer(socket => {
    socket.on('data', data => {
        console.log(data.toString())
    })
}).listen(1234)

I receive the data fine. A line of data received looks like 'DATA,zoneA,20'.

Now I want to write that stream of data to this http server:

const express = require('express')
const morgan = require('morgan')
const app = express()
const bodyParser = require('body-parser')
const {PORT} = 3000

app.use(morgan('tiny'))
app.use(express.json())
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({extended: true}))


const catchTCP = async dataLine => {
    dataLine = 'DATA,zoneA,20' 
    try {
        if (dataLine.indexOf("DATA") >= 0) {
            var stream = dataLine.split(",")
            var streamData = {
                zone: stream[1],
                battery: stream[2]
            }
            console.log(streamData)
        }
    } catch(err) {
        console.log("error:", err)
    }
}

catchTCP()

app.listen(PORT, () => console.log(`App listening at http://localhost:${PORT}`))

I would like to replace the 'dataLine' object by an entry point for this TCP/IP data. What would be the best way to forward TCP/IP data to the HTTP server's port?

Both servers run on the same network, so I've been told socket.io would not be the best fit.

Solution

Replace the catchTCP function on your HTTP server with a middleware route:

app.post("/receive", express.text(), function(req, res) {
  var dataLine = req.body;
  /* Your code from catchTCP */
  res.end(); /* finish the HTTP response */
});

Then your TCP/IP server can send an HTTP request with the following code:

var s = net.createConnection(PORT, "localhost", function() {
s.end(`POST /receive HTTP/1.1
Content-Type: text/plain
Content-Length: ${data.toString().length}

${data}`);
});

This is the TCP/IP-level representation of the HTTP request. But I would not do it that way, I would rather use a proper HTTP client. Which is not a problem if your TCP/IP server is programmed in Node.js anyway:

const http = require("http");
http.request("http://localhost:${PORT}/receive", {
  method: "POST",
  headers: {"Content-Type": "text/plain"}
}).end(data.toString());