GCM

<?php
/**
* @param apiKey - ключ для GCM, получить можно в https://code.google.com/apis/console/
* @param registrationIdsArray - массив токенов устройств
* @param messageData - массив данных уведомления, например: array('message' => "Hey!")
*/
function sendGCMNotification( $apiKey, $registrationIdsArray, $messageData )
{
    $headers = array("Content-Type:" . "application/json", "Authorization:" . "key=" . $apiKey);
    $data = array(
        'data' => $messageData,
        'registration_ids' => $registrationIdsArray
    );
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_HEADER, false); 
    curl_setopt($ch, CURLOPT_VERBOSE, false); 
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers );
    curl_setopt($ch, CURLOPT_URL, "https://android.googleapis.com/gcm/send" );
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0 );
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0 );
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true );
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data) );

    $response = curl_exec($ch);
    $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    $header_size = curl_getinfo($ch,CURLINFO_HEADER_SIZE);

    curl_close($ch);
    return $response;
}