Cannot connect to socket.io connection in node.js - node.js

Question

I'm new to node.js and, having worked through the relevant parts of the Wexler book, I am trying to create a simple stream using socket.io.
Here is my node.js server code:
const port = 3000,
dataIntervalMillis = 5000,
express = require("express"),
app = express(),
crypto = require('crypto');
const server = app
// .get("/", (req, res) => {
// res.send("Run this project by typing in <b>nodemon</b> in the node.js command prompt.");
// })
.listen(port, () => {
console.log(`RNG Server running on port number ${port}`);
}),
io = require("socket.io")(server);
io.on("connection", client => {
console.log("RNG client connected.");
io.emit("New RNG client connection.");
client.on("disconnect", () => {
console.log("RNG client disconnected.");
io.emit("RNG client disconnected.");
});
});
I have built a standalone Java application to test the stream:
//import java.io.BufferedReader;
import java.io.InputStream;
//import java.io.InputStreamReader;
//import java.io.PrintStream;
import java.net.Socket;
public class SimpleSocketClientExample {
public static void main(String[] args) {
String server = "localhost";
int port = 3000;
try {
// Connect to the server
System.out.println("Connect to server " + server + " on port " + port + "...");
Socket socket = new Socket( server, port );
System.out.println("...connected.");
//BufferedReader in = new BufferedReader( new InputStreamReader( socket.getInputStream() ) );
InputStream in = socket.getInputStream();
System.out.println("Reading byte...");
int b = in.read();
System.out.println("...byte read.");
// Close our streams
if (in != null) {
in.close();
}
if (socket != null) {
socket.close();
}
}
catch( Exception e ) {
e.printStackTrace();
}
}
}
The problem is that this client code hangs on the in.read() line.
The only console log from the server is RNG Server running on port number 3000. There is no RNG client connected in the server log, which indicates that the client has not connected (or has connected to something else).
I've tested my node.js app using online socket testers, and they don't seem to connect either - indicating the problem probably lays with my node.js server app.
Can anyone advise what I may have missed?

Answer 1

Turns out socket.io doesn't create a standard TCP socket.
My solution was to leave my client code untouched and change the Node.js server code to use the net library instead.
In case it might help anyone else that runs into the same issue, here's my new code:
const port = 3000;
const { createServer } = require('net');
const server = createServer();
// A counter to facilitate assigning of socket.id.
let counter = 0;
// An array of connected client sockets that we will broadcast to.
let sockets = {};
server.on('connection', (socket) => {
socket.id = counter++;
console.log(`A client has connected: ${socket.id}`);
// Catch errors so they don't stop the application.
socket.on('error', function () {
console.log(`Client error: ${socket.id}`);
delete sockets[socket.id];
});
// Set character encoding.
socket.setEncoding('utf8');
// Add socket to array.
sockets[socket.id] = socket;
// When connection ends, remove socket from array.
socket.on('end', data => {
console.log(`${socket.id} has disconnected`)
delete sockets[socket.id];
});
});
server.listen(port, () => {
console.log(`RNG Server running on port number ${port}`);
});