<?php

$xml = <<<_XML
<?xml version="1.0"?> 
<aws:UrlInfoResponse xmlns:aws="http://a...content-available-to-author-only...s.com/doc/2005-10-05/">
  <aws:Response xmlns:aws="http://a...content-available-to-author-only...s.com/doc/2005-07-11">
    <aws:OperationRequest>
    </aws:OperationRequest>
    <aws:UrlInfoResult>
      <aws:Alexa>
        <aws:TrafficData>
          <aws:DataUrl type="canonical">google.com/</aws:DataUrl> 
          <aws:Rank>1</aws:Rank> 
        </aws:TrafficData>
      </aws:Alexa>
    </aws:UrlInfoResult>
    <aws:ResponseStatus xmlns:aws="http://a...content-available-to-author-only...s.com/doc/2005-10-05/">
      <aws:StatusCode>Success</aws:StatusCode> 
    </aws:ResponseStatus>
  </aws:Response>
</aws:UrlInfoResponse>
_XML;

$xml = simplexml_load_string($xml, null, null, 'aws', true);

print_r($xml);
echo $xml->Response->UrlInfoResult->Alexa->TrafficData->Rank;