1. Google Cloud Messaging for
Android
Shcheglov Maksym
MTS1 at Magento inc.

2. Google Cloud Messaging for Android
GCM & C2DM
• no signup to get access;
• no authentication using Google account;
• no message quota.

3. Google Cloud Messaging for Android
Requirements
• Android 2.2 or higher;
• Google account (OS version < Android 4.0.4);
• project ID (using Google API console);
• API key (using Google API console).

4. Google Cloud Messaging for Android
Requirements

5. Google Cloud Messaging for Android
Requirements

6. Google Cloud Messaging for Android
Enabling GCM
GCM Server
Sender ID,
Application ID
2
1
Registration ID Registration ID
3
Mobile phone

7. Google Cloud Messaging for Android
Enabling GCM
import com.google.android.gcm.GCMRegistrar;
public class UAMobileActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final String regID = GCMRegistrar.getRegistrationId(this);
if (regID.equals("")) {
// register application
GCMRegistrar.register(this, "484449755275");
} else {
// Device is already registered on GCM
}
}
}

8. Google Cloud Messaging for Android
Enabling GCM
import com.google.android.gcm.GCMBaseIntentService;
public class GCMIntentService extends GCMBaseIntentService {
@Override
protected void onRegistered(Context context, String registrationID) {
//send registrationID to the server
registerOnServer(context, registrationID);
}
}

9. Google Cloud Messaging for Android
Sending a message
1
GCM A message with API
Server
key,
Registration ID
2
Mobile phone

10. Google Cloud Messaging for Android
Sending a message
Request
https://android.googleapis.com/gcm/send
HTTP headers:
Content-Type:application/json
Authorization:key=AIzaSyAIpOT5VHEOthyrwKjwrNwwEVHQIgioypk
HTTP body:
{
“collapse_key” : “news_update”,
“time_to_live” : 100,
“delay_while_idle” : true,
"data" : { ... },
"registration_ids" : [”ID1”, “ID2”, “ID3”],
}

11. Google Cloud Messaging for Android
Sending a message
Response
{
"multicast_id": 112,
"success": 2,
"failure": 1,
"canonical_ids": 1,
”results": [
{ “message_id": "1:2036" },
{ "message_id": "1:7695", "registration_id": ”102" },
{ "error": "NotRegistered"}
]
}

12. Google Cloud Messaging for Android
Sending a message
Client
import com.google.android.gcm.GCMBaseIntentService;
public class GCMIntentService extends GCMBaseIntentService {
@Override
protected void onMessage(Context context, Intent intent) {
// received the message
final Bundle bundle = intent.getExtras();
String data = bundle.getString("some_data");
}
}

13. Google Cloud Messaging for Android
Unregistration
• manually by sending an intent
com.google.android.c2dm.intent.UNREGI
STER;
• uninstall the application;
• registration ID is expired;
• application is updated, but does not have a broadcast
receiver configured to receive
com.google.android.c2dm.intent.RECEIV
E intents.

14. Google Cloud Messaging for Android
Unregistration
Device not
registered error
5
1
4
GCM Server
invalidate
2
3
Mobile phone

15. Google Cloud Messaging for Android
Message states
• sent;
• stored (a device is offline);
• collapsed (a device is offline & we have a new message);
• throttled.

16. Google Cloud Messaging for Android
Concepts
• send-to-sync;
• message with payload.

17. Google Cloud Messaging for Android
Features
• no broadcasting;
• no guarantees about delivery and order;
• message multicasting (up to 1000 devices per 1 request);
• multiple senders (max 100 project IDs per application);
• store up to 100 non-collapsible messages;
• maximum 4kb per message;
• optimizations;
• analytics.

18. Google Cloud Messaging for Android
How to migrate from C2DM
Client
• deliver a new version of your app;
• send a flag with registration ID.
Server
• new endpoint;
• API key in the Authorization header.

19. Google Cloud Messaging for Android
GCM & APNS
• no certificates;
• one http address for development and production;
• uses json or plaint text in requests, not binary data;
• no feedback service;
• developer-friendly error codes;
• no actions (alert/badge/sound);
• message size (4kb & 256b).

20. Demo

21. Q&A