Using PHP cURL to send a message (with retry in case of failure) to a Google Cloud Messaging registered device.

gistfile1.php

<?php

define('CURL_EXEC_RETRY_MAX',3);
define('GCM_SERVER_URL',"https://android.googleapis.com/gcm/send");
define('GCM_API_KEY',"YOUR_API_KEY");

/**
 * Using PHP to send a message to a Google Cloud Messaging registered device is quite simple. 
 * In this class we're using curl to create a message request to send to the Google GCM server.
 * This class require an GCM Api key cf. {@link https://code.google.com/apis/console/}
 * 
 * @author Michael
 *
 */
class App_GCMdriver {

    private $ch;
  	private $response;
  	private $info;
  	private $http_code;

  	public function __construct() {
		//-- init cURL an set options		
  		$this->ch = curl_init();
  		curl_setopt( $this->ch, CURLOPT_URL, GCM_SERVER_URL );
	  	curl_setopt( $this->ch, CURLOPT_SSL_VERIFYHOST, 0 );
	  	curl_setopt( $this->ch, CURLOPT_SSL_VERIFYPEER, 0 );
	  	curl_setopt( $this->ch, CURLOPT_RETURNTRANSFER, true );
  	}

	/**
   	 * The following function will send a GCM notification using curl.
   	 *
   	 * @param $apiKey					[string] The Browser API key string for your GCM account
   	 * @param $registrationIdsArray 	[array]  An array of registration ids to send this notification to
   	 * @param $messageData				[array]	 An named array of data to send as the notification payload
   	 */
	public function sendNotification( $registrationIdsArray, $messageData )
  	{
  		$headers = array("Content-Type:" . "application/json", "Authorization:" . "key=" . GCM_API_KEY);
  		$data 	 = array(
  			'data' => $messageData,
  			'registration_ids' => $registrationIdsArray
  		);
  		
  		//-- Complementary options for GCM service
  		curl_setopt( $this->ch, CURLOPT_HTTPHEADER, $headers );
	  	curl_setopt( $this->ch, CURLOPT_POSTFIELDS, json_encode($data) );
	  	
	  	return $this->exec();
  	}
  	
  	/**
  	 * Execute query with retry
  	 */
  	private function exec(){
  		$this->retryExec();
  		$this->info = curl_getinfo($this->ch);
  		$this->http_code = $this->info['http_code'];
		  $response = $this->response;
		  curl_close($this->ch);
  		return $response;
  	}
  	
  	/**
  	 * Query with retry executor
  	 */
  	private function retryExec(){
      $i = 0;
  		while ($i++ < CURL_EXEC_RETRY_MAX) {
  			$this->response = curl_exec($this->ch);
  			if ($this->response) break;
  			if ($i < CURL_EXEC_RETRY_MAX) sleep($i);
  		}
    }
  	
  	public function getHttpCode() {return $this->http_code;}
  	public function getExecResponse() {return $this->response;}
  	public function getExecInfo() {return $this->info;}
  	public function getError() {return curl_error($this->ch);}
}


$regId = "A_DEVICE_REGISTRATION_ID";
$gcm = new App_GCMdriver();
$result = $gcm->sendNotification( array($regId), array('message' => 'hello !!') );
print_r($result);