mchess-client/lib/connection/ws_connection.dart

import 'package:web_socket_channel/web_socket_channel.dart';

class ServerConnection {
  late WebSocketChannel channel;
  late int counter = 0;

  static final ServerConnection _instance = ServerConnection._internal();

  ServerConnection._internal() {
    print("ServerConnection._interal constructor is called");
    channel = WebSocketChannel.connect(
      Uri.parse('ws://localhost:8080'),
    );
  }

  factory ServerConnection() {
    return _instance;
  }

  factory ServerConnection.getInstance() {
    return ServerConnection();
  }

  void send(String message) {
    channel.sink.add('$counter $message');
    counter++;
  }

  void reconnect() {
    channel = WebSocketChannel.connect(Uri.parse('ws://localhost:8080'));
  }
}