public function setStyle($style)
    {
        if (!in_array($style, array(SOAP_RPC, SOAP_DOCUMENT))) {
            require_once 'Zend/Soap/Client/Exception.php';
            throw new Zend_Soap_Client_Exception('Invalid request style specified. Use SOAP_RPC or SOAP_DOCUMENT constants.');
        }

        $this->_style = $style;

        $this->_soapClient = null;

        return $this;
    }