Creating websocket chat rooms - php

Question

I have a working Ratchet chat socket server, however everyone who connects has the ability to chat with everyone. How can I implement rooms in code, I want users to be able to chat in rooms that arent visible to everyone connected on the server
ChatServer.php
<?php
require_once 'vendor/autoload.php';
use Ratchet\Server\IoServer;
use Ratchet\MessageComponentInterface;
use Ratchet\ConnectionInterface;
use Ratchet\Http\HttpServer;
use Ratchet\WebSocket\WsServer;
echo "Hello";
class Chat implements MessageComponentInterface {
protected $clients;
public function __construct() {
$this->clients = new \SplObjectStorage;
}
public function onOpen(ConnectionInterface $conn) {
// Store the new connection to send messages to later
$this->clients->attach($conn);
echo "New connection! ({$conn->resourceId})\n";
}
public function onMessage(ConnectionInterface $from, $msg) {
$numRecv = count($this->clients) - 1;
echo sprintf('Connection %d sending message "%s" to %d other connection%s' . "\n"
, $from->resourceId, $msg, $numRecv, $numRecv == 1 ? '' : 's');
foreach ($this->clients as $client) {
if ($from !== $client) {
// The sender is not the receiver, send to each client connected
$client->send($msg);
echo $msg;
}
}
}
public function onClose(ConnectionInterface $conn) {
// The connection is closed, remove it, as we can no longer send it messages
$this->clients->detach($conn);
echo "Connection {$conn->resourceId} has disconnected\n";
}
public function onError(ConnectionInterface $conn, \Exception $e) {
echo "An error has occurred: {$e->getMessage()}\n";
$conn->close();
}
}
$server = IoServer::factory(
new HttpServer(
new WsServer(
new Chat()
)
),
8080
);
$server->run();
If any additional code is needed or if the question is unclear please let me know