Introduction to Android

Google Cloud Messaging

Amrit SanjeevOrganizer – Bangalore Android User Group

About me

• Android hacker.

• Organizer, Bangalore Android User Group ( www.blrdroid.org )

• Research Engineer at Philips R&D

Bangalore Android User Group ( www.BlrDroid.org)

• Largest open Android developer community in the country and second largest in the world.

• Over 2500 members

• 19 meetups

• 3 hackathons

• Active participation in events like Droidcon, Global Android Developer hackathon etc

What we will be discussing today.

Google Cloud Messaging

1What is GCM?

2Why do we

need GCM?

3How it is

implemented ?

What is GCM?

Google Cloud Messaging

1

GCM definition

GCM stands for Google Cloud Messaging .

It is a free service that allows developers to send data from third party servers to their applications running on android devices

Handles queuing of messages and delivery to the target application running on the target device.

Intended use is not to send huge amount of data to the client device

Things to keep in mind

Application on the android device DOES NOT need to be running to receive messages.

Requires user to set up a Google account on the device.

It is purely a routing component

There is no guaranteed delivery of messages to the device .

Focus of GCM

Ease of use. No sign-up forms. No quotas.

GCM stats are available

through the Android

Developer Console.

Battery efficiency.

Rich set of new APIs

Difference between GCM and C2DM

Simple API Key from Google APIs console page.

Sender id is the project id rather than email address

Supports data in JSON format and plain text

Difference between GCM and C2DM

Multicast message support

Multiple senders

Messages have time to live ( 0 ~ 4 weeks ) eg. Expiring invitations

Payload up to 4kb

2 Why do we need GCM?

The why part

The need to use GCM

Client server architecture is the most common architecture . Most application do all the heavy lifting

and processing at the servers and then use the processed data within the applications .

Scalability & extensibilityMore computing power

The need to use GCM

Background process polling server for information at regular intervals is a bad design Battery performanceSystem resource usage ( memory , CPU )Complicated coding

Application does not need to be running in the background for receiving data messages.

Lower cost and better tracking than SMS.

The need to use GCM

Less coding requiredNot need to worry about queuing of

messagesDiffered delivery

Simpler application flow

The need to use GCM

In a nutshell it makes application design much more simple, improves

battery performance and makes better use of system resources .

3 How it is implemented?

The internals

Major components

Your application server

GCM servers

Mobile device

Typical sequence of events

The application server sends a

message to GCM servers.

Google queues and stores the

message in case the device

is offline.

When the device is

online, Google sends the

message to the device.

On the device, the system

broadcasts the message to the

specified Android. This

wakes the Android

application up.

The Android application

processes the message

option

al

Minimum requirements ( device side )

Android 2.2 +

Android market place should be installed

Emulator with Google APIs

Internet connection

Google account ( device version < 4.0.4 ).

Minimum requirements ( server side )

HTTPS application server that should be Able to communicate with your client.Able to fire off HTTP requests to the

GCM server.Able to handle requests and queue data

as needed. For example, it should be able to perform exponential back off.

Able to store the user device registration id .

Android application

Copy the

required libs

Make changes to the

manifest

Add a broadca

st receiver

Add an Intent

service

Wire it up in your

activity

Alternate Infrastructures

• Alternative to GCM is required under following conditions Limited connectivity to internet servicesSecurity requirement Guaranteed delivery SLAs on deliveryNo quota limits

• DownsidesComplicated designBattery consumption on device is higher.

Thank you In case you have more queries please feel free to contact

Amrit.sanjeev@gmail.com (+91 97407 44557 )@amsanjeev

BACKUP SLIDES

Add required libs

Install Google Cloud Messaging for

android using SDK manager.

Copy gcm.jar from YOUR_SDK_ROOT/extras/google/gcm-client/dist

to libs in your project folder

Changes to Manifest file

Add <use-sdk … >Declare & use a custom permission Add additional permissions

internet get_accounts wake_lock

Write Intentservice

subclass of com.google.android.gcm.GCMBaseIntentService

must contain a public constructor, Generally named

my_app_package.GCMIntentServiceOverride the following functions with appropriate

logiconRegisteredonUnRegisteredonMessageonErroronRecoverableError

Add boardcast receiver

add a broadcast receiver with the custom permissions and following actions <action android:name="com.google.android.c2dm.intent.RECEIVE" /> <action

android:name="com.google.android.c2dm.intent.REGISTRATION" />

Should be defined in the manifest and not programmatically

Finally the activity

CheckDevice ()CheckManifest()getRegistrationId()Register()