Possible to have multiple receiver ids in GoogleCloudMessaging?

Question

I am following this tutorial:

http://www.androidhive.info/2012/10/android-push-notifications-using-google-cloud-messaging-gcm-php-and-mysql/

my app is getting gcm_regid, that is stored in mysql. With this id, I can send message via php to chosen regid;

but when i deinstall the application - and reinstall, it get's a new reg_id - thats ok too, this is stored in mysql too.

But when I send a message to the first gcm_regid (this was it's previous gcm_regid) the phone is getting that message too, even it has got a new gcm_regid (due to reinstall) - why is that so, and how can I delete the previous id? and where is that id? in my device? stored in gcm server?

and a second question:

do I have to take majour changes when I change GCMRegistrar in the tutorial above to Google Cloud Messaging - what I have to do there

Answer 1

When GCM assigns a new Registration ID to your device, the previous IDs that were assigned to it continue to work. If you send a message to an older Registration ID assigned to your device, the message will be delivered, but your server will get a response containing a canonical Regsitration ID, which is the newest Registration ID of that device. If you get such a response, you should delete the old Registration ID from your DB.

As for your second question, you don't have to make major changes in order to stop using GCMRegigtrar and use GoogleCloudMessaging instead. In fact, your code should look simpler after you make that change.

1. You'll have one call to GoogleCloudMessaging.register inside an AsyncTask in one of your activities. This method has to be called in an AsyncTask because it's blocking, so it can't be executed on the main thread. The good thing about it is that you get the response in the same place you call the method, and don't have to wait for it in the GCMBroadCastReceiver/IntentService.

2. Your GCMBroadcastReceiver/IntentService will have to handle just incoming messages. They won't have to deal with registration anymore.

Here's a partial example of the new registration process, taken from the official GCM Demo :

/**
 * Registers the application with GCM servers asynchronously.
 * <p>
 * Stores the registration ID and the app versionCode in the application's
 * shared preferences.
 */
private void registerInBackground() {
    new AsyncTask<Void, Void, String>() {
        @Override
        protected String doInBackground(Void... params) {
            String msg = "";
            try {
                if (gcm == null) {
                    gcm = GoogleCloudMessaging.getInstance(context);
                }
                regid = gcm.register(SENDER_ID);
                msg = "Device registered, registration ID=" + regid;

                // You should send the registration ID to your server over HTTP, so it
                // can use GCM/HTTP or CCS to send messages to your app.
                sendRegistrationIdToBackend();

                // For this demo: we don't need to send it because the device will send
                // upstream messages to a server that echo back the message using the
                // 'from' address in the message.

                // Persist the regID - no need to register again.
                storeRegistrationId(context, regid);
            } catch (IOException ex) {
                msg = "Error :" + ex.getMessage();
                // If there is an error, don't just keep trying to register.
                // Require the user to click a button again, or perform
                // exponential back-off.
            }
            return msg;
        }

        @Override
        protected void onPostExecute(String msg) {
            mDisplay.append(msg + "\n");
        }
    }.execute(null, null, null);
}