title: how to get the list of devices which are registered in Google Cloud Messaging server
body: <p>after reading the sample code for my server: </p>
  
  <pre><code>// Replace with real BROWSER API key from Google APIs
  $apiKey = "123456";
  
  // Replace with real client registration IDs 
  $registrationIDs = array( "123", "456" );
  
  // Message to be sent
  $message = "x";
  
  // Set POST variables
  $url = 'https://android.googleapis.com/gcm/send';
  
  $fields = array(
               'registration_ids'  =&gt; $registrationIDs,
               'data'              =&gt; array( "message" =&gt; $message ),
                );
  
  $headers = array( 
                   'Authorization: key=' . $apiKey,
                   'Content-Type: application/json'
               );
  
  // Open connection
  $ch = curl_init();
  
  // Set the url, number of POST vars, POST data
  curl_setopt( $ch, CURLOPT_URL, $url );
  
  curl_setopt( $ch, CURLOPT_POST, true ); 
  curl_setopt( $ch, CURLOPT_HTTPHEADER, $headers);
  curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
  
  curl_setopt( $ch, CURLOPT_POSTFIELDS, json_encode( $fields ) );
  
  // Execute post
  $result = curl_exec($ch);
  
  // Close connection
  curl_close($ch);
  </code></pre>
  
  <p>it is required to know the registration_ids from the server to push information.</p>
  
  <p>how to get the list of registered devices (registration_ids) in GCM server from my personal server.</p>
  
  <p>how to send a broadcast message to all devices registered in GCM. </p>
  
  <p>Thank's !</p>