public function getBaseData()
    {
        $data = new FluidXml(false);

        $message = $data->addChild('Message', ['version' => $this->getApiVersion()], true);

        $header = $message->addChild('Header', true);
        $header->addChild('Time', $this->getTime());

        $itentity = $header->addChild('Identity', true);
        $itentity->addChild('UserID', $this->getUserId());

        $body = $message->addChild('Body', ['type' => 'GetInvoice', 'live' => $this->getLive()], true);
        $order = $body->addChild('Order', ['paymentMethod' => $this->getPaymentMethod()], true);

        $order->addChild('MerchantID', $this->getMerchantId());
        $order->addChild('SiteAddress', $this->getSiteAddress());
        $order->addChild('PostbackURL', $this->getNotifyUrl());
        $order->addChild('SuccessURL', $this->getReturnUrl());
        $order->addChild('FailureURL', $this->getCancelUrl());

        return $message;
    }