Android OS

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Android OS
Kesav Kaliyaperumal kesav.kaliyaperumal_at_gmail.com
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Yummy Desserts!

• Cupcake
• Donuts
• Éclair
• Frozen Yoghurt (Froyo)
• Gingerbread
• Honeycomb
• What do these have in common?

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Smartphone OS

• Symbian
• Windows Mobile
• RIM Blackberry OS
• Apple iOS
• Google Android
• Palm WebOS
• Windows Phone 7

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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

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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

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Software Stack

• Linux kernel
• Libraries
• Android run time
• core libraries
• Dalvik virtual machine
• application layer
• application protocol

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Android Architecture
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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

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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

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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

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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

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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

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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

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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

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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

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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

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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)

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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

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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

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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

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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

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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

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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

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Resources

• http//www.android.com
• http//http//android-developers.blogspot.com
• http//developer.motorola.com/