Wait for cURL response from a second Ratchet/ZeroMQ server - php

Question

I'm developing a solution where I send a POST request from the first server to the second server using cURL.
function sendIcuCurlRequest($identity, $action, $payload){
$url = '-- Removed --';
$data = array(
'identity' => $identity,
'action' => $action,
'payload' => $payload
);
$fields = http_build_query($data);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, count($data));
curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);
curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$result = curl_exec($ch);
curl_close($ch);
return $result;
}
On the second server where the cURL request is picked up, ZeroMQ sends the data using SOCKET_PUSH to the WebSocket server (WebSocket server is on the second server).
if(isset($_POST['identity'], $_POST['action'], $_POST['payload'])){
$identity = $_POST['identity'];
$action = $_POST['action'];
$payload = $_POST['payload'];
$context = new ZMQContext();
$socket = $context->getSocket(ZMQ::SOCKET_PUSH, 'ICU push');
$socket->connect('tcp://127.0.0.1:21002');
$socket->send(json_encode(array('identity' => $identity, 'message' => formatRequest($action, $payload))));
exit;
} else {
echo "Invalid request";
exit;
}
The WebSocket server then makes a RPC Call to the Client.
public function onNewRequest($request){
$requestData = json_decode($request, true);
echo "Outgoing new request for Charge Point: ".var_export($request, true)."\n";
// Check if is valid Station
if(!array_key_exists($requestData['identity'], $this->stations)){
echo "Identity {$requestData['identity']} not found.\n";
return;
}
$station = $this->stations[$requestData['identity']];
$res = $station->send(json_encode($requestData['message']));
file_put_contents(dirname(__FILE__).'/../../logs/broadcast-'.date('Ymd').'.log', print_r($res, true)."\n\n", FILE_APPEND);
}
The Client after some thinking sends a CallResult to an onCallResult method with the response. (Note: I've modified Ratchet's WAMP core so it would be possible to receive CallResults from the Client)
public function onCallResult(ConnectionInterface $conn, $id, array $params){
$url = $conn->WebSocket->request->getUrl();
echo "URL path -- ".$url."\n";
echo "IP -- ".$conn->remoteAddress."\n";
echo "Incoming call result (ID: $id)\n";
echo "Payload -- ".var_export($params, true)."\n";
}
Now to the fun part
Now that I have the response from the Client, I would like to send that response back with cURL using the same connection the initial request came through.
I am thinking that with cURL alone I wouldn't be able to achieve this (I found that there is a new method like curl_pause but that is for 5.5 and up. Current server is running 5.4).
I did also find that ZeroMQ has a socalled REQ and REP but I can't quite figure out if that will serve the prupose on getting it work like this.
What would be the best for me to send a cURL response back to the initial request that came?