Socket.to is not a function

[pepper28]

I have employed the response to the client socket method as socket.to(sessionID).emit(txId); and I received the following error message. TypeError: socket.to is not a function. Everything I have read has said this is the appropriate way to send the response from the server to a specific client. Please HELP!
^

[darrachequesne]

Hi! That's weird, the to() method should indeed exist. Could you please provide a sample project reproducing the issue?

[pepper28]

I've tried the following "socket.to(sessionID).emit(txId);", "socket.emit(txId);", and "server.to(sessionID).emit(txId);". My client is a java machine and although I'm sending userInfo and points successfully using, "socketWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())); " to Nodejs socket.io. I can only receive the txId if the method I'm using is socket.to(sessionID).emit(txId), but this crashes Nodejs. If I use socket.emit(txId) Java client running " socketReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));" never gets call or txId data.

My environment for both the Java client and the NodeJS Server is Ubuntu Linux version 18.04.

Here is my Node JS code

const server = require('net').createServer();
const RPCClient = require('');
const { SocketAddress } = require('net');
const { Socket } = require('socket.io');
const avcCRC = new RPCClient('');
const socket = require('socket.io')(server);

server.on('connection', socket =>{
  console.log('Client connected');
  const sessionID = socket.id;   
  var remoteAddress = socket.remoteAddress + ":" + socket.remotePort
 socket.on('data',data => { 
   //socket.write(data);
   const commaIndex = data.indexOf(",");
   userInfo = data.substring(0, commaIndex);
   console.log(userInfo);
   points = data.substring(commaIndex +1);
   console.log(points);
  
   avcCRC.call('passphrase', 'tester28', 15).then(() => {
   avcCRC.call('senduserInfo', userInfo, points).then(txId => {
    
  socket.to(sessionID).emit(txId);
  //socket.emit(txId);
  
   console.log('The result is:  ' + txId );     
});
});
});
            
socket.setEncoding('utf8');
socket.once("close", function(){
console.log("connection from %s closed", remoteAddress);
});

socket.on("error", function(err){
  console.log("connection %s error: %s", remoteAddress, err.message);
});

});

   server.listen(9000, () => console.log('server is listening on port 9000'));

Edit by @darrachequesne: format

[darrachequesne]

Hi! I think you need to pass a HTTP server (require('http').createServer()), and not a TCP server (require('net').createServer()):

const { createServer } = require("http");
const { Server } = require("socket.io");

const httpServer = createServer();
const io = new Server(httpServer, { /* options */ });

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

Reference: https://socket.io/docs/v4/server-initialization/#with-an-http-server

[pepper28]

Damien, I want to thank you. Although I thought using the base TCP networking method would have been sufficient your resolution solved my issue. Thank you again.

[pepper28]

I have written a very minimal NodeJS stub to see if any of the code was interfering with "sockect.to' operating. Even in this minimal configuration, I am receiving the following error.

Process exited with code 1
Uncaught TypeError TypeError: socket.to is not a function
at (/home/boulder/BCNode/interop5.js:17:11)
at emit (events:513:28)
at addChunk (internal/streams/readable:315:12)
at readableAddChunk (internal/streams/readable:285:11)
at Readable.push (internal/streams/readable:228:10)
at onStreamRead (internal/stream_base_commons:190:23)
at callbackTrampoline (internal/async_hooks:130:17)
--- TCPWRAP ---
at init (internal/inspector_async_hook:25:19)
at emitInitNative (internal/async_hooks:202:43)
No debugger available, can not send 'variables'

Here is the minimal code I used.

const server = require('net').createServer();
const socket = require('socket.io')(server);

server.on('connection', socket =>{
console.log('Client connected');
const sessionID = socket.id;
socket.on('data',data => {
socket.write(data);
const commaIndex = data.indexOf(",");
userInfo = data.substring(0, commaIndex);
console.log(userInfo);
points = data.substring(commaIndex +1);
console.log(points);

socket.to(sessionID).emit("Trying to send info to the client");

});

socket.setEncoding('utf8');
});

server.listen(9000, () => console.log('server is listening on port 9000'));