Acknowledgement.php

<?php

namespace React\Stomp;

class Acknowledgement
{
    private $client;
    private $messageId;
    private $subscriptionId;

    public function __construct($client, $messageId, $messageId)
    {
    }

    public function ack()
    {
    }

    public function nack()
    {
    }
}

example.php

<?php

$client->subscribe('/topic/foo', function ($frame, $acknowledgement) {
    if ($problem) {
        $acknowledgement->nack();
    } else {
        $acknowledgement->ack();
    }
}, 'client');