CODEWITHSUNDEEP
androidpush-notificationgoogle-cloud-messaging
Nish
Nish

Reputation: 101

GoogleCloudMessaging Android

I am confused while implementing the upstream message using the new GoogleCloudMessaging APIs :

public void onClick(final View view) {
    if (view == findViewById(R.id.send)) {
        new AsyncTask() {
            @Override
            protected String doInBackground(Void... params) {
                String msg = "";
                try {
                    Bundle data = new Bundle();
                    data.putString("hello", "World");
                    String id = Integer.toString(msgId.incrementAndGet());
                    gcm.send(SENDER_ID + "@gcm.googleapis.com", id, data);
                    msg = "Sent message";
                } catch (IOException ex) {
                    msg = "Error :" + ex.getMessage();
                }
                return msg;
            }

            @Override
            protected void onPostExecute(String msg) {
                mDisplay.append(msg + "\n");
            }
        }.execute(null, null, null);
    } else if (view == findViewById(R.id.clear)) {
        mDisplay.setText("");
    } 
}

We send the messages(XMPP) to GCM server using the SENDER_ID id, so how can my third party server identify my device only with the SENDER_ID?

gcm.send(SENDER_ID + "@gcm.googleapis.com", id, data);

Upvotes: 0

Views: 302

Answers (1)

Eran
Eran

Reputation: 394146

The code you posted sends a message from your device to your 3rd server, not to another device. Your server should establish a connection with the Cloud Connection Server, and since establishing that connection requires using SENDER_ID + "@gcm.googleapis.com" for user name, the GCM server can identify your 3rd party server.

When you 3rd party server sends a message to your device, it uses the Registration ID, which identifies your app on a specific device.

EDIT :

I may have misunderstood your question. If you are asking how does the 3rd party server know which device sent the upstream message to it, the message that your 3rd party server receives contains the Registration ID of the sender, as you can see here :

<message id="">
  <gcm xmlns="google:mobile:data">
  {
      "category":"com.example.yourapp", // to know which app sent it
      "data":
      {
          "hello":"world",
      },
      "message_id":"m-123",
      "from":"REGID"
  }
  </gcm>
</message>

Even though you don't specify the Registration ID when you call gcm.send(...), GCM knows which device sent the message, so (assuming your app registered to GCM and therefore has a Registration ID) they can add the Registration ID to the message (I'm not sure if they add it on the client side before connecting the GCM server, or if the add it at the GCM server, but it doesn't really matter).

Upvotes: 2

Related Questions