How Do I Send Multiple Notification And Multiple Devices Using Gcm For Android Using Php? Help Me To Send Multiple Messages To Multiple Devices

$var = select * from table;

foreach($var as $varliable)
{
   $to_device_id = $varliable['id']
   $message = array("unread"=>$msg);  // storing multiple messages
   $device_id = array($to_device_id); // storing multiple device ids

   $gcmObj->send_notification($device_id, $message); // this function is called in another page test.php
}

function send_notification($device_id, $message="")
{
   $curl = 'https://android.googleapis.com/gcm/send';

   // how to replace the device id and messages here. 

   $field= array(
      'registration_ids' => $device_id,
      'field' => $message,
      );
   $headers = array(
      'Authorization: key=' . GOOGLE_API_KEY,
      'Content-Type: application/json'
      );
   $ch = curl_init();
   curl_setopt($ch, CURLOPT_URL, $curl);
   curl_setopt($ch, CURLOPT_POST, true);
   curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
   curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
   curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
   curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($field));
   $result = curl_exec($ch);      
   curl_close($ch);
   echo $result;
}