Android OS

Yummy Desserts!

• Cupcake• Donuts• Éclair• Frozen Yoghurt (Froyo)• Gingerbread• Honeycomb

What do these have in common?

Smartphone OS

• Symbian

• Windows Mobile

• RIM Blackberry OS

• Apple iOS

• Google Android

• Palm WebOS

• Windows Phone 7

Android OS

• Fastest growing mobile OS• Over 300,000 Android activations a day• Android overtook iOS as the dominant OS

in US during 2H 2010• First phone launched HTC G1 in 2008• Currently an OS of choice for Motorola,

HTC, Samsung, Sony Ericsson, among others

• Software updates every few months

Android – what is it?• software stack for mobile devices

– incl. OS, middleware and key applications• Open source – source code is open and contributions are welcome• application framework enabling reuse/replacement of apps• Dalvik virtual machine optimized for mobile• integrated browser based on webkit• Optimized graphics – 2D graphics library, 3D based on OPEN GL

ES• SQLite for data storage• Media support (MPEG4, H.264, MP3, AAC, JPG, PNG,…)• Support for radio interfaces, Bluetooth, WiFi, Camera, GPS,

accelerometer• Software Development Kit (SDK)• Preinstalled applications from Google (GMS)

– Gmail, Maps, Search, Voice Search, Youtube

Software Stack

• Linux kernel

• Libraries

• Android run time– core libraries– Dalvik virtual machine

• application layer

• application protocol

Android Architecture

Android

• Google Maps and other GMS applications• Background services and applications

– allows multi tasking of applications

• Shared Data and interprocess communication• All applications are equal

– does not discriminate between native and non-native applications

– allows any applications to be enhanced/reused

• p2p interdevice application messaging

Dalvik VM

• All applications written in Java and converted to the dalvik executable .dex

• Every android app runs its own process, with its own instance of the dalvik virtual machine

• Not a traditional JVM, but a custom VM designed to run multiple instances efficiently on a single device

• VM uses linux kernel to handle low-level functionality incl. security, threading, process and memory management

Application Framework• Rich, extensible set of Views

– apps can inclused lists, grids, text boxes, buttons, web browser

• Content Providers– allows data access from other applications or share

own data• Resource Manager

– access to localized strings, graphics, layout files• Notification Manager

– enables custom alerts to be displayed in status bar• Activity Manager

– Manages lifecycle of applications and provides navigation backstack

Application Fundamentals• Activities

– application presentation layer• Services

– invisible components, update data sources, visible activities, trigger notifications– perform regular processing even when app is not active or invisible

• Content Providers– shareable data store

• Intents– message passing framework– broadcase messages system wide, for an action to be performed

• Broadcast receivers– consume intent broadcasts– lets app listen for intents matching a specific criteria like location

• Notifications– Toast notification– Status Bar Notification– Dialog notification

Applications

• All apps (native and 3rd party) are written using the same APIs and run on the same run time executable

• All apps have APIs for hardware access, location-based services, support for background services, map-based activities, 2D and 3D graphics.

• App Widgets are miniature app views that can be embedded in other apps like Home Screen

App Priority and Processes

Android apps do not have control over their own life cycles

Aggressively manages resources to ensure device responsiveness and kills process/apps when needed

• Active Process – critical priority• Visible Process – high priority• Started Service Process• Background Process – low priority• Empty process

Client apps

• Developed using the Android SDK and installed on user devices

• Compiled Java code, with data and resource – bundled by Android Asset Packaging tool (AAPT) into Android package or .apk

• All applications have Android Manifest file in its root directory– provides essential information about app

• Could be installed directly on phone, but necessary to be distributed thru Market

Web Apps

• An alternative to standalone apps

• Developed using web standards and accessed through browser – nothing to install on devices

• Mixing client and web apps is also possible – Client apps can embed web pages using “Webview” in Android app

SDK• Android APIs, Full Documentation and Sample code• Development tools

– Dalvik Debug Monitor Service (DDMS)– Android Debug Bridge (ADB)– Android Emulator

• Online support and blog• Native Development Kit also available

– allows developers to implement parts of apps in native-code languages like C/C++

– Plug in available to use Eclipse integrated development environment

• Developer forums and developer phones from Google, MOTO Dev studio from Motorola

Android Market• Google Market - Part of GMS apps• 3rd party apps submitted to Google, approved and distributed

through Market• Both Free and Paid apps• Apps now limited to 50 MB; updates possible through Market• Monetization through ads available• Available in many countries, not all countries have support for paid

apps• Other Market place applications available – Amazon has announced

its own Android Market place• App searches filtered based on Manifest file (eg. if a device does

not have trackball, apps using trackball will be filtered out)• Every app publishes a list of components the app will access and

permissions need to be granted before installation• Apps installed on device and SD card (SD Card from Froyo)

Search

• Core feature in android• User should be able to search any data on

device or internet• Usually one of the android buttons• Search suggestions based on recent queries• Provide custom search suggestions that match

actual results in application data• system side Quick Search Box• Voice Search available and enhanced in recent

releases

Locations & Maps

• Compelling and most popular apps for mobile devices

• Google Maps provides free navigation• applications allowed access to location

services supported by device• Google provides Maps external library

– allows built-in downloading, rendering and caching of Maps tiles, and other display options and controls

Device Administration

• Froyo introduces support for enterprise applications with Device Administraion API

• allows to create security-aware applications to control employee devices

• Apps might include– Email clients– remote wipe– device management services and apps

Android Software Updates

• Android 1.0 – G1• 1.5 – Cupcake• 1.6 – Donuts (CDMA support)• 2.0 – Éclair (Droid introduced with Éclair)• 2.2 – Froyo• 2.3 Gingerbread (SDK released 2 weeks ago and source

will follow soon)• API Levels used by apps to identify software version on

the device• Android apps are generally forward compatible with

newer version, but not necessarily backwards compatible

Compatibility

• Why?– Allow customizable devices– Create Common eco system

• Android compatibility is free and easy– Obtain Android source code– Comply with Android Compatibility Definition (ACD) doc

• List requirements that need to be met for devices to be compatible with a particular version on Android

– Pass the Compatibility Test Suite (CTS)• Automated test harness running on desktop, manages test

exectuion• Test cases written, packaged as .apk to run on actual device or

emulator

• Porting guide available for bringing up Android on custom HW

Other possibilities

• Google TV - a new platform based on Android

• Tablets – Samsung Galaxy tab introduced in Oct 2010

• eBook reader – Latest Barnes and Noble Nook is an Android tablet