<?php

$installer = $this;
$installer->startSetup();

$installer->getConnection()
    ->addColumn($installer->getTable('sales/order'),'piyush_order_exported', array(
        'type'      => Varien_Db_Ddl_Table::TYPE_TEXT,
        'nullable'  => true,
        'length'    => 10,
        'after'     => null, // column name to insert new column after
        'comment'   => 'Is order exported'
    ));

$installer->endSetup();

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <modules>
        <Piyush_OrderExport>
            <version>1.0.0</version>
        </Piyush_OrderExport>
    </modules>
    <global>
        <helpers>
            <Piyush_orderexport>
                <class>Piyush_OrderExport_Helper</class>
            </Piyush_orderexport>
        </helpers>
        <models>
            <Piyush_orderexport>
                <class>Piyush_OrderExport_Model</class>
            </Piyush_orderexport>
        </models>
        <resources>
            <Piyush_orderexport_setup>
                <setup>
                    <module>Piyush_OrderExport</module>
                </setup>
            </Piyush_orderexport_setup>
        </resources>
        <events>
            <sales_order_save_after>
                <observers>
                    <Piyush_orderexport_order_save_after>
                        <type>singleton</type>
                        <class>Piyush_OrderExport_Model_Observer</class>
                        <method>exportOrder</method>
                    </Piyush_orderexport_order_save_after>
                </observers>
            </sales_order_save_after>
        </events>
    </global>
</config>

<?php

class Piyush_OrderExport_Helper_Data extends Mage_Core_Helper_Abstract
{
    const LOG_ENABLED_CONFIG_PATH = 'productimport/general_config/log_enabled';
    const LOG_FILE_NAME = 'Piyush_orderexport.log';

    /**
     * Utility function to log a message to the log file, if logging is enabled
     * @param string log message
     */
    public function log($message) {
        if (Mage::getStoreConfig(self::LOG_ENABLED_CONFIG_PATH)) {
            Mage::log($message, null, self::LOG_FILE_NAME);
        }
    }
}

<?php
class Piyush_OrderExport_Model_Observer
{
    const EXPORT_RELATIVE_PATH = 'var/export/orders/';
    const EXPORT_FILE_NAME = 'orderexport.xml';
    const FTP_HOST = "your.erp.ip.address";
    const FTP_PORT = 21;
    const FTP_USER = "";
    const FTP_PASSWORD = "";

    protected function sendFile($filePath, $fileName)
    {
        $_helper = Mage::helper('Piyush_orderexport');
        $_helper->log('Uploading the file to the FTP server...');
        if ($ftpResource = ftp_connect(self::FTP_HOST, self::FTP_PORT))
        {
            if (ftp_login($ftpResource, self::FTP_USER, self::FTP_PASSWORD))
            {
                if (ftp_put($ftpResource, $fileName, $filePath, FTP_ASCII))
                {
                    $_helper->log("Upload of remote file '$fileName' complete (source file is '$filePath').");
                } else {
                    $_helper->log("Warning: error cannot upload the file!");
                }
            } else
            {
                $_helper->log("Warning: error cannot login to the FTP server! Can't upload the file.");
            }
        } else
        {
            $_helper->log("Warning: error connection to the FTP server! Can't upload the file.");
        }
    }

    public function exportOrder(Varien_Event_Observer $event=null)
    {
        $_helper = Mage::helper('Piyush_orderexport');

        $importStartDateTime = date('Y-m-d H:i:s');
        $_helper->log('*** EXPORT ORDER START - ' . $importStartDateTime . ' ***');

        /* @var Mage_Sales_Model_Order $order */
        $order = $event->getOrder();
        //$order = Mage::getModel('sales/order')->loadByIncrementId('100000042');

        $orderIncrementId   = $order->getIncrementId();
        $orderTimestamp     = strtotime($order->getCreatedAt());
        $orderDate          = date("ymd", $orderTimestamp);
        $orderTime          = date("Hi", $orderTimestamp);
        $orderShipping      = number_format(round($order->getShippingInclTax(), 2),2);

        $_helper->log('Processing order '.$orderIncrementId);
        $_helper->log('Order state = '.$order->getState());
        $_helper->log('Order has been exported is '.$order->PiyushOrderExported());


       if ($order->PiyushOrderExported() != '1' && $order->getState() == $order::STATE_NEW) {

            $_helper->log('Exporting order '.$orderIncrementId);
            $_helper->log("t- date = $orderDate");
            $_helper->log("t- time = $orderTime");
            $_helper->log("t- shipping = $orderShipping");

            $xmlFilePath = Mage::getBaseDir('base') .'/'. self::EXPORT_RELATIVE_PATH . self::EXPORT_FILE_NAME;
            $outputFileHandler = fopen($xmlFilePath,"w");

            $orderItems = $order->getAllVisibleItems();
            foreach ($orderItems as $item)
            {
                //$_helper->log("Item data: ".print_r($item->getData(),true));

                $itemSku                = $item->getSku();
                $itemQty                = number_format(round($item->getQtyOrdered(), 2),2);
                $itemRowTotal           = number_format(round($item->getRowTotal(), 2),2,'.','');
                $itemRowTotalInclTax    = number_format(round($item->getRowTotalInclTax(), 2),2,'.','');
                $itemTaxAmount          = number_format(round($item->getTaxAmount(), 2),2,'.','');
                $itemPlu                = Mage::getModel('catalog/product')->loadByAttribute('sku', $itemSku)->PiyushPlu();

                $_helper->log("t- processing order item $itemSku:");
                $_helper->log("tt- qty = $itemQty");
                $_helper->log("tt- row total = $itemRowTotal");
                $_helper->log("tt- tow total incl tax = $itemRowTotalInclTax");
                $_helper->log("tt- tax amount = $itemTaxAmount");
                $_helper->log("tt- PLU = $itemPlu");

                $xmlString="";
                /* create your xml here */

                fputs($outputFileHandler,$xmlString);
                //$_helper->log("xmlString = $xmlString");

            }

            fclose($outputFileHandler);

            $this->sendFile($xmlFilePath, self::EXPORT_FILE_NAME);

            $order->setGcmOrderExported('1');
            $order->save();

            $importEndDateTime = date('Y-m-d H:i:s');
            $_helper->log('*** EXPORT ORDER END - ' . $importEndDateTime . ' ***'.PHP_EOL.PHP_EOL);
        }
    }
}

<?xml version="1.0"?>
<config>
    <modules>
        <Piyush_OrderExport>
            <active>true</active>
            <codePool>local</codePool>
        </Piyush_OrderExport>
    </modules>
</config>