Sending a broadcast notification with Google Cloud Messaging - notifications

Question

I am using Google Cloud Messaging to provide push notifications. I may need to send a broadcast notification to around 10.000 users. However, I read that a Multicast message can contain a list with 1000 registration ids, maximun.
So, do I need to send ten multicast messages? Is there any way to send a broadcast to all the clients without generating the lists with all the ids?
thanks in advace.

Answer 1

Since Play Services 7.5, it's now also possible to achieve this through topics:
https://developers.google.com/cloud-messaging/topic-messaging
After registering, you would have to send the GCM server a message over HTTP:
https://gcm-http.googleapis.com/gcm/send
Content-Type:application/json
Authorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA
{
"to": "/topics/foo-bar",
"data": {
"message": "This is a GCM Topic Message!",
}
}
E.g.:
JSONObject jGcmData = new JSONObject();
JSONObject jData = new JSONObject();
jData.put("message", "This is a GCM Topic Message!");
// Where to send GCM message.
jGcmData.put("to", "/topics/foo-bar");
// What to send in GCM message.
jGcmData.put("data", jData);
// Create connection to send GCM Message request.
URL url = new URL("https://android.googleapis.com/gcm/send");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty("Authorization", "key=" + API_KEY);
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestMethod("POST");
conn.setDoOutput(true);
// Send GCM message content.
OutputStream outputStream = conn.getOutputStream();
outputStream.write(jGcmData.toString().getBytes());
And your clients should subscribe to /topics/foo-bar :
public void subscribe() {
GcmPubSub pubSub = GcmPubSub.getInstance(this);
pubSub.subscribe(token, "/topics/foo-bar", null);
}
#Override
public void onMessageReceived(String from, Bundle data) {
String message = data.getString("message");
Log.d(TAG, "From: " + from);
Log.d(TAG, "Message: " + message);
// Handle received message here.
}

Answer 2

You have no choice but splitting your broadcast in chunks of maximum 1000 regIds.
You can then send your multicast messages in separate threads.
//regIdList max size is 1000
MulticastResult multicastResult;
try {
multicastResult = sender.send(message, regIdList, retryTimes);
} catch (IOException e) {
logger.error("Error posting messages", e);
return;
}