Posting XML with PHP using Zend Framework HTTP Client

Here is the code to construct XML using SimpleXML in PHP and send a request using Zend Framework's HTTP Client:

$xml = new \SimpleXMLElement('<request/>');
$xml->addChild(
    'partner',
    $this->credentials['aaa']);
$order = $xml->addChild('order');
$order->addAttribute('order_id', $orderId);
$order->addChild('status', $status);

$client = new \Zend_Http_Client();
$client->setUri('https://....');
$client->setRawData($xml->asXML(), 'text/xml');
$response = $client->request('POST');