อยากทราบวิธีการเชื่อมต่อ php กับ google spreadsheets ครับ

$xml = "
<entry xmlns='http://www.w3.org/2005/Atom'
    xmlns:gsx='http://schemas.google.com/spreadsheets/2006/extended'>
  <gsx:id>123</gsx:id>
  <gsx:status>123</gsx:status>
  <gsx:date>4/26/2014</gsx:date>
  <gsx:user>bob</gsx:user>
</entry>";

//set headers which includes auth from elsewhere in the code
$headers = array(
    "Authorization: GoogleLogin auth=" . $auth,
    "GData-Version: 3.0",
    "Content-Type: application/atom+xml",
    );

//post the xml. The key in the url is taken from the actual url when you view the sheet 
$curl = curl_init();
curl_setopt($curl, CURLOPT_POST, 1);
curl_setopt($curl, CURLOPT_URL, "https://spreadsheets.google.com/feeds/list/xxxxxxxxxxxxxxxkeyxxxxxxxxx/0/private/full");
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
curl_setopt($curl, CURLOPT_POSTFIELDS, "$xml");
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
$response = curl_exec($curl);