Client does not received message from socket js server - unity3d

Question

I am working on to establish a message communication between UWP Application on desktop and the Hololens 1.
According to the implementation of Websockets from Microsoft Documentation Websocket Implementation I could
implement the signalling part to the Nodejs with socket.io Server
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
app.get('/', function(req, res){
res.sendFile(__dirname + '/index.html');
});
var PORT = 3000;
var userId = 0;
http.listen(PORT, function () {
console.log('listening on *: ' + PORT);
});
io.on('connection', function(socket){
socket.userId = userId++;
console.log('a user connected, user id: ' + socket.userId);
socket.on('mess', function (msg) {
console.log('message from user#' + socket.userId + ": " + msg);
// Send message with emit"mess" to all client
io.emit('mess', msg);
});
socket.on('disconnect', function(){
console.log('user disconnected');
});
});
Both client (uwp app and the hololens could establish to the Server.
On the computer I could send some data to the server.
The problem I currently have is that the Hololens does not receive a message from the server.
For the communication part I use a wrapper class which provide sending and receiving functions for 2 clients. This wrapper class has been generated to dll inorder to reference in 2 difference projekt (uwp app and unity app for hololens)
// Declare "Using" part here...
namespace SocketWrapperNamespace
{
public delegate void OnReceiveMessengerCallback(string msg);
public delegate void OnDisconnectCallback(bool connect);
public class SocketWrapper
{
public event OnReceiveMessengerCallback OnReceiveMessenger;
public event OnDisconnectCallback onDisconnect;
#if !UNITY_EDITOR
private Uri _uri;
private MessageWebSocket messageWebSocket;
private DataWriter dataWriter;
#endif
// Client can call this function to connect
public void Connect(string uri)
{
#if !UNITY_EDITOR
try
{
Connector(uri);
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
#endif
}
private async void Connector(string uri)
{
#if !UNITY_EDITOR
// Code here look pretty much like in the example from microsoft documentation
#endif
}
// Function for client to send message to server
public void SendMessage(string emiter, string message)
{
#if !UNITY_EDITOR
try
{
Emit(emiter, message);
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
#endif
}
//Emitter
private async void Emit(string emiter, string message)
{
#if !UNITY_EDITOR
try
{
if (messageWebSocket == null)
{
return;
}
if (dataWriter == null)
{
return;
}
string form = string.Format("42[\"{0}\",\"{1}\"]", emiter, message);
dataWriter.WriteString(form);
await dataWriter.StoreAsync();
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
#endif
}
//Disconnect
public void Disconnect()
{
#if !UNITY_EDITOR
// Disconnecting server ...
#endif
}
//Message Arrived Handler
private void WebSocket_MessageArrived(MessageWebSocket sender, MessageWebSocketMessageReceivedEventArgs args)
{
#if !UNITY_EDITOR
try
{
if (OnReceiveMessenger == null)
{
return;
}
using (DataReader dataReader = args.GetDataReader())
{
if (dataReader != null)
{
dataReader.UnicodeEncoding = UnicodeEncoding.Utf8;
string message = dataReader.ReadString(dataReader.UnconsumedBufferLength);
OnReceiveMessenger?.Invoke(message);
}
}
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
#endif
}
//Websocket Close Handler
private void WebSocket_Closed(IWebSocket sender, WebSocketClosedEventArgs args)
{
#if !UNITY_EDITOR
// Close work here ...
#endif
}
}
On the Hololens I prepare the connection to server and listen to the received message event.
// hololens client call this method to initialize the connection
public void OnStart()
{
socketWrapper = new SocketWrapper();
uri = String.Concat("ws://",server,":3000/socket.io/?EIO=3&transport=websocket");
#if !UNITY_EDITOR
socketWrapper.Connect(uri);
socketWrapper.OnReceiveMessenger += OnMessageArrived_Handler;
socketWrapper.onDisconnect += OnDisconnect_Handler;
#endif
}
//Message Arrived Handler
private void OnMessageArrived_Handler(string msg)
{
// Here I do not received any message from server
}
What mistake did I make her ? I wonder that even though I can connect to the server from hololens but the subscribe part seem not to work ?
Consider the 2 projects are on different location and the same happen to the dll.
I think that I have to setup the SocketWrapper class as Singleton because hololens part instantiate a new Object therefor the subscribing may not work here
Any better suggestion for solve this problem with other implementation would be helpful.
Thanks

Answer 1

I think the best solution now for using WebSocket in C# and Unity environment is WebSocketSharp library.
It has a great implementation and kept up to date for 6 years till now. Also it has 3 examples of how to use it in different scenarios.