Problem with [[!CDATA ]]

Sometimes when you load the xml file, you didn't get the data between the tags [[!CDATA ]]. This is the character data and you can't get with simplexml_load_file library. In that case use that function as below, so that it will escape the CDATA from url.
$xml = simplexml_load_file($url, 'SimpleXMLElement', LIBXML_NOCDATA)

Cross domain data exchange

You can use XML language to transfer large data from one domain to other. Suppose domain-x wants to send data from its database to domain-y. Then domain-x will generate xml file for the database and send it to the domain-y via post method for security purpose. Upon receipt of xml file from domain-x, the domain-y will store that xml file in one folder and create one new row in received_xml table, and call a xmlparser script through cron job to extract information from the xml files and store in database and then move that parsed xml file to some other folder(named like parsed) and remove the record from receive_xml table.

For parsing there are so many free scripts available in php,ruby etc., xmltoarray is one of the technique.