sending push notifications to multiple android devices using GCM

Question 1

I am following http://javapapers.com/android/google-cloud-messaging-gcm-for-android-and-push-notifications/? to send push notifications via GCM. Everything works fine but, i am able to send push notification to just one device. Registering another device replaces registration id of previous device. I tried solution provided by Shardool in http://javapapers.com/android/android-multicast-notification-using-google-cloud-messaging-gcm/? but its not working.

Any suggestion would be of great help.

Here are my gcm.php codes that registers device and sends push notifications but, only to a single device registered recently.

gcm.php

<?php
//generic php function to send GCM push notification
function sendPushNotificationToGCM($registatoin_ids, $message) {
    //Google cloud messaging GCM-API url
    $url = 'https://android.googleapis.com/gcm/send';
    $fields = array(
        'registration_ids' => $registatoin_ids,
        'data' => $message,
    );
    // Google Cloud Messaging GCM API Key
    define("GOOGLE_API_KEY", "MY_KEY");       
    $headers = array(
        'Authorization: key=' . GOOGLE_API_KEY,
        'Content-Type: application/json'
    );
    $ch = curl_init();
    curl_setopt($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));
    $result = curl_exec($ch);             
    if ($result === FALSE) {
        die('Curl failed: ' . curl_error($ch));
    }
    curl_close($ch);
    return $result;
}
?>
<?php
//this block is to post message to GCM on-click
$pushStatus = "";   
if ( ! empty($_GET["push"])) { 
    $gcmRegID  = file_get_contents("GCMRegId.txt");
    $pushMessage = $_POST["message"];   
    if (isset($gcmRegID) && isset($pushMessage)) {      
        $gcmRegIds = array($gcmRegID);
        $message = array("m" => $pushMessage);  
        $pushStatus = sendPushNotificationToGCM($gcmRegIds, $message);
    }       
}
//this block is to receive the GCM regId from external (mobile apps)
if ( ! empty($_GET["shareRegId"])) {
    $gcmRegID  = $_POST["regId"]; 
    file_put_contents("GCMRegId.txt",$gcmRegID);
    echo "Ok!";
    exit;
}   
?>
<html>
    <head>
        <title>Google Cloud Messaging (GCM) Server in PHP</title>
    </head>
    <body>
        <h1>Google Cloud Messaging (GCM) Server in PHP</h1> 
        <form method="post"   action="gcm.php/?push=1">                                              
            <div>                                
                <textarea rows="2" name="message" cols="23" placeholder="Message to transmit via   GCM"></textarea>
            </div>
            <div><input type="submit"  value="Send Push Notification via GCM" /></div>
        </form>
        <p><h3><?php echo $pushStatus; ?></h3></p>        
    </body>
</html>

Please tell me how do I store multiple device registration ids in GCMRegid.txt and send notifications to each of the registered device

Question 2

Here I rewrote the php using mysql rather than retrieving the keys from file. In this case, I retrieve all the regIds from the table and put them in an array and pass it to sendPushNotification function to push the message to all. here you have 2 files, one for connect to database and one for GCM:

connect.php:

<?php

    $db_host = "localhost";
    $db_user = "root"; //change to your database username, it is root by default
    $db_pass = '';     //change to your database password, for XAMPP it is nothing for WAMPP it is root
    $db_db = 'gcmFirst'; //change to your database name

    if(!@mysql_connect($db_host, $db_user, $db_pass) || !@mysql_select_db($db_db)) {
        die('couldnt connect to database ' .mysql_error());
    }

?>

gcm.php

<?php
require 'connect.php';

function sendPushNotification($registration_ids, $message) {

    $url = 'https://android.googleapis.com/gcm/send';
    $fields = array(
        'registration_ids' => $registration_ids,
        'data' => $message,
    );

    define('GOOGLE_API_KEY', 'AIzaSyCjctNK2valabAWL7rWUTcoRA-UAXI_3ro');

    $headers = array(
        'Authorization:key=' . GOOGLE_API_KEY,
        'Content-Type: application/json'
    );
    echo json_encode($fields);
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));

    $result = curl_exec($ch);
    if($result === false)
        die('Curl failed ' . curl_error());

    curl_close($ch);
    return $result;

}

$pushStatus = '';

if(!empty($_GET['push'])) {

    $query = "SELECT regId FROM users";
    if($query_run = mysql_query($query)) {

        $gcmRegIds = array();
        while($query_row = mysql_fetch_assoc($query_run)) {

            array_push($gcmRegIds, $query_row['regId']);

        }

    }
    $pushMessage = $_POST['message'];
    if(isset($gcmRegIds) && isset($pushMessage)) {

        $message = array('message' => $pushMessage);
        $pushStatus = sendPushNotification($gcmRegIds, $message);

    }   
}

if(!empty($_GET['shareRegId'])) {

    $gcmRegId = $_POST['regId'];
    $query = "INSERT INTO users VALUES ('', '$gcmRegId')";
    if($query_run = mysql_query($query)) {
        echo 'OK';
        exit;
    }   
}
?>

<html>
    <head>
        <title>Google Cloud Messaging (GCM) Server in PHP</title>
    </head>
    <body>
    <h1>Google Cloud Messaging (GCM) Server in PHP</h1>
    <form method = 'POST' action = 'gcm.php/?push=1'>
        <div>
            <textarea rows = 2 name = "message" cols = 23 placeholder = 'Messages to Transmit via GCM'></textarea>
        </div>
        <div>
            <input type = 'submit' value = 'Send Push Notification via GCM'>
        </div>
        <p><h3><?php echo $pushStatus ?></h3></p>
    </form>
    </body>
</html>

all you have to do is create a database that has a users table with id, regId and name as columns.

Hope this is what you are looking for

Question 3

Solved!!!

you must use Key for server apps (with IP locking) instead of browser key

:)

Question 4

As a little background this is for a university setting where multiple colleges apps as well as distance education may be using the service. Here is the approach that we are using in our organization. If you look at the way APNS works it can be used by just sending a web call to the APNS service with the token id. GCM is very close to the same type of system. Basically create a JSON package and send it to the desired service.

Here is our steps we used to create this service.

Server admins created a server and database that can be called that will collect the tokens from both android and ios devices. When the device registers we also send what type of device it is. This is possible since we are just sending data to the database that is has been created.
From here we then created a couple of python scripts that send the data do the desired service whether it is ios or android. These scripts gather the appropriate data from the database and sends the packaged data (JSON package) to APNS for ios message and GCM for google cloud.
We also created a web interface so that those who need to send messages to the devices can.

The rest of the implementation is up to you to decide the best way to utilize the service. For example when to check for invalid devices, Because we are planning on using this same server for multiple applications we can send the type of device, token, application, or whatever else is needed for an application to distinguish it from others we produce so that each application that wants to use the service can. I hope this helps and gives you some idea on how to accomplish this.

Question 5

Is there a way to send messages to all devices without pass the registrarions id?

No way.
After successfully registering on GCM, you (the Android application) should send the registration id to your application server and store them somewhere, in a database for example. This registration id will be used to send a notification to a particular device.

To send a notification to all devices, would mean then to select all the registration ids from that database, and as you said, put them in an array and pass them further to GCM.

Update: With Firebase Cloud Messaging, it is now possible to use https://firebase.google.com/docs/cloud-messaging/android/topic-messaging to send notifications without explicitly specifying registration IDs.

Question 6

Update: For v1, it seems that registration_ids is no longer supported. It is strongly suggested that topics be used instead.

When sending to specified multiple registration tokens, you must use registration_ids instead of to. From the docs (emphasis mine):

This parameter specifies the recipient of a multicast message, a message sent to more than one registration token.

The value should be an array of registration tokens to which to send the multicast message. The array must contain at least 1 and at most 1000 registration tokens. To send a message to a single device, use the to parameter.

Multicast messages are only allowed using the HTTP JSON format.

var message = {
    registration_ids: regTokens,

   data: { 
        ar_message: messageToSend
   }
  };

sending push notifications to multiple android devices using GCM

Answers

php,android,notifications,google-cloud-messaging