Google Cloud Messaging (GCM) is a service that allows servers to send messages to Android devices. It handles message delivery and requires minimal battery consumption compared to regular polling. To use GCM, an Android app registers with the GCM server to receive a registration ID and the server sends messages addressed to that ID. When a device receives a message, the GCM service passes the data to the Android app via a intent. GCM supports unlimited messaging at no cost.

1. Google Cloud Messaging - Android
Swapnal Agrawal

2. • How to keep the data on your device app
- Updated & Fresh
Can use Notifications ?????
How to send notification
msg
data

3. How to send notification
• Polling
 App checks the server periodically
 Easy to implement
 Good for frequent content change
But……
It reduces bandwidth and battery resources
If there isn’t any new data, we’re still checking

4. How to send notification
• Pushing
 App waits for information to get sent to it.
 Constant Connection
 Less Battery Consumption
But…
A bit complex to implement

5. What is GCM?
 Google Cloud Messaging for Android (GCM) is a
service that allows you to send data from your server to
your users' Android-powered device.
 The GCM service handles all aspects of queueing of
messages and delivery to the target Android application
running on the target device
 GCM is completely free no matter how big your
messaging needs are, and there are no quotas.

6. How efficient is it?
 Easy to use
 It allows 3rd-party application servers to send messages
to their Android applications.
 An Android application on an Android device doesn't
need to be running to receive messages.
 Limitless Quotas
 Battery Efficiency
 Rich set of new API’s

7. Limitations of GCM
The device must be running 2.2 or greater.
The device must have the Marketplace
installed.
Your app needs additional permissions in
the manifest.

8. GCM Building Blocks
• Components :-
 Mobile Device
 3rd party App Server
 GCM Server
• Credentials :-
 SenderId
 ApplicationId
 RegistrationId
 Google User Account
 Sender Auth Token

9. GCM Registeration
Android Device
5. Intent Broadcast
Service
App
View
Application
Server
GCM
Service
App
View
1. Register for
Notification
2. Send
Registration ID
3. Send
Notification
4. Send
Message

10. GCM LifeCycle
• Enabling GCM.
An Android application running on a mobile device
registers to receive messages.
• Sending a message.
A 3rd-party application server sends messages to
the device.
• Receiving a message.
An Android application receives a message from a
GCM server.

11. Enabling GCM
 You should have one google account login
 If you already have existing projects, the first page you see will be
the Dashboard page. From there you can create a new project by opening
the project drop-down menu (upper left corner) and choosingOther
projects > Create.
 Click Create project. Your browser URL will change to something like:
https://code.google.com/apis/console/#project:219845360754
Enable the GCM service:
 In the main Google APIs Console page, select Services.
 Turn the Google Cloud Messaging toggle to ON.
 In the Terms of Service page, accept the terms.

12. Enabling GCM
Obtain API key as per the steps given at
http://developer.android.com/google/gcm/gs.html

13. Import com.google.android.gcm.GCMRegistrar;
@Override
protected void onCreate(Bundle
savedInstanceState)
{
GCMRegistrar.register(this, “219845360754”);
}
GCM Registration
GCM
GCM
Framework
Project Id

14. GCM – Android Manifest
<manifest package="com.example.gcm" ...>
<uses-sdk android:minSdkVersion="8" android:targetSdkVersion="16"/>
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
<permission android:name="com.example.gcm.permission.C2D_MESSAGE"
android:protectionLevel="signature" />
<uses-permission android:name="com.example.gcm.permission.C2D_MESSAGE" />
<application ...>
<receiver
android:name=".MyBroadcastReceiver"
android:permission="com.google.android.c2dm.permission.SEND" >
<intent-filter>
<action android:name="com.google.android.c2dm.intent.RECEIVE" />
<action android:name="com.google.android.c2dm.intent.REGISTRATION" />
<category android:name="com.example.gcm" />
</intent-filter>
</receiver>
<service android:name=".GCMIntentService" />
</application>
</manifest>

15. GCM – Sending Message
Server Side Application :-
import com.google.android.gcm.server.Message;
import com.google.android.gcm.server.Result;
import com.google.android.gcm.server.Sender;
[..]
public Result sendMessage(final String device, final String message) throws
IOException
{
Sender sender = new Sender(getApiKey());
Message gcmMessage = new Message.Builder().addData("payload",
message)
.collapseKey("0").build(); return sender.send(gcmMessage, device, 5);
}

16. GCM – Receive Message
GCM
GCM
Framework
RegId {Intent}
• System receives the incoming message
and extracts the raw key/value pairs
• System passes key/value pairs to targeted
Android Application in a
com.google.android.c2dm.intent.RECEIVE
Intent as a set of extras
• Android application extracts the raw data
from the Intent by key and processes the
data

17. GCM – Receive Message
import com.google.android.gcm.server.Message;
import com.google.android.gcm.server.Result;
import com.google.android.gcm.server.Sender;
[..]
public Result sendMessage(final String device, final String message) throws
IOException
{
Sender sender = new Sender(getApiKey());
Message gcmMessage = new Message.Builder().addData("payload",
message)
.collapseKey("0").build(); return sender.send(gcmMessage, device, 5);
}

18. References
• https://docs.google.com/presentation/d/1qQPT653uUrKFXYUxPE7gy-
5Kii0UupxS6K8TvAwfnXI/edit#slide=id.p74
• http://developer.android.com/google/gcm/gs.html
• http://developer.android.com/google/gcm/gcm.html
• https://bremen-
gtug.googlecode.com/svn/presentations/2012_12_03/Google%20Cloud%20
Messaging/template.html#3
• http://www.fppt.com (PPT templates)