How to communicate with the WebSockets service

I have taken the example of Chat in Socketo.me. I have the chat-server.php :

<?php
use Ratchet\Server\IoServer;
use Ratchet\Http\HttpServer;
use Ratchet\WebSocket\WsServer;
use MyApp\Chat;

    require dirname(__DIR__) . '/vendor/autoload.php';

    $server = IoServer::factory(
        new HttpServer(
            new WsServer(
                new Chat()
            )
        ),
        8080
    );

    $server->run()

I also have the Chat.php

<?php
namespace MyApp;
use Ratchet\MessageComponentInterface;
use Ratchet\ConnectionInterface;

class ConnectionStorage extends \SplObjectStorage
{
    public function getClientObject($idConnection){

        $this->rewind();
        while ($this->valid()) {
            $object = $this->current(); // similar to current($s)
            $id = $object->resourceId;
            if ($idConnection === $id) {
                $this->rewind();
                return $object;
            }
            $this->next();
        }
    }
}

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);
            }
        }
    }

    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();
    }

public static function  sendMessage($idResource, $msg)
    {
        $client = $this->clients->getClientObject($idResource);
        $client->send($msg);
    }
}

Do everything and it works perfectly. My question is if I have a file on the same server called X.php , how can I refer to the context of the web sockets and send a message to a user I know of his resourceId. Something like X.php :

<?php //X.php

$idResource = $_GET['idSocket'];
$msg = $_GET['mensaje'];

Chat::sendMessage($idResource,$msg);