public function __construct($username, $password)
 {
     $wsseNamespace = 'http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd';
     $wssePasswordNS = 'http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText';
     $wsseUserVar = new SoapVar($username, XSD_STRING, null, null, 'Username', $wsseNamespace);
     $wssePassVar = new SoapVar($password, XSD_STRING, type, $wssePasswordNS, 'Password', $wsseNamespace);
     $wsseUserPassVar = new SoapVar(array($wsseUserVar, $wssePassVar), SOAP_ENC_OBJECT, null, null, 'UsernameToken', $wsseNamespace);
     $security = new SoapVar(array($wsseUserPassVar), SOAP_ENC_OBJECT);
     parent::SoapHeader($wsseNamespace, 'Security', $security, 1);
 }