/**
* @param $wsdl
* @param array $options
* @param array $headers
*/
protected function build_soap_client($wsdl, $options = array(), $headers = array())
{
$soap = Soap::Client($wsdl, $options);
$soap->__setSoapHeaders(new SoapHeader($this->__get('ns'), 'RequestHeader', $headers));
return $soap;
}