A brief introduction to Android OS, its libraries, structure, and Application development and framework.

1. Mobile Applications SIG Event:
Developing
for the Android OS
Presented by:
Has Taiar

2. Android OS Overview

3. Overview
 Android Overview (What? & Why?)
 SDK and Development Tools.
 Android architecture, building blocks, and security.
 Applications’ Framework and Components.
 Comparable Features of Android.
 Q&A and Demo

4. What is Android?
 Modern open-source mobile operating system
 Full software stack
 Linux kernel 2.6
 Java middleware, framework
 core applications
 Google & OHA
Goals (Being better, open, and standard) and vision.
 Latest Release 4.0 (Ice Cream Sandwich)

5. Why Android?
 open-source
oapache license
ocost
osetsdevelopers free
solid foundation: Linux kernel
good framework based on Java
empower users
oreplace core apps
oPersonalize
Google stuff
huge opportunity for vendors, developers, users
oOS for free, innovate at app level
not just for phones

6. SDK & Dev Tools
 All major platforms supported
(linux, windows, and mac)
 NDK for porting native code
 OEM USB Driver
 ADT for Eclipse v 18.0.0
SDK Package manager & AVD Manager
 33.9 MB for the Starter SDK (core)
 clean and compact
 good documentation
 4.0.3 latest version
 Alternative Dev tools

7. SDK & Dev Tools (cont)
 Eclipse and ADT
 Emulator
 adb tool from the command line
o Android Debug Bridge
o ex: adb install <path_to_apk>
 other third party tools for UI generating,
sensors readings, etc.

8. SDK & Dev Tools (cont)
So what are the development approaches?
 Eclipse and ADT
 Mono for Android
 HTML 5 & Javascript
o Titanium Appaccelator
o PhoneGap
 Google App Inventor (MIT)
 Android App Makers like andromo
 Wordpress and its alike

9. SDK & Dev Tools (cont)

10. Architecture & Building Blocks

11. Architecture & Building Blocks
 Linux 2.6 based
 Provides hardware management
o File System
o Memory management
o Network (3G, EDGE, Wifi, BT)
o Camera
o Keyboard
o Power Management

12. Architecture & Building Blocks
Libraries
 Graphics
o OpenGL, Scalable Image, Animations
 Media
o Images (.png, .jpeg, etc)
o Videos (.mp4, .3gp, .wmv, etc)
o Audio (.mp3, .mp4 etc)
 Local Storage
o File System, and SQLite.
 Security
o SSL library
Integrated Web Browser
o Webkit based
oUses Google Chrome
oCSS 3, HTML5, Animation, etc

13. Architecture & Building Blocks
Android Runtime
 Dalvik
o A virtual machine executing apps
o Java development language
 Provides some supporting libraries
o HTTPClient, XML Parsing, JSON, etc

14. Architecture & Building Blocks
Applications Framework
 Functionality managed by the system
Underlying framework for your app
development
 Sharing common functionality.
 This makes all apps are:
o Equal
o can use any of the mentioned
functionalities
o can cooperate together

15. App Architecture
 Activity
visible screens
 Service
background services
 Content Provider
shared data
 Broadcast receivers
receive and react to broadcasted events
 Intent
activating components
 AndroidManifest.xml

16. App Architecture (Cont.)
Activity
 Visual User Interface for one task
o ex: list of menu items & input fields
 Work together to form a cohesive UI
 One of the activities is marked as the
first or main starting point.
Can use additional UI elements such as
pop-ups and dialogue boxes

17. App Architecture (Cont.)
Activity Life-cycle
Activity Layout and Life-cycle

18. App Architecture (Cont.)
Services
Run in the background for an indefinite
period of time
 Interact with services using API or through
UI interfaces.
 A service starts via a UI element, does not
stop even after the activity gets disposed.
Difference between Create() & Bind()
 Can communicate with other services.
 Examples:
o Media player service
o Location Monitor Service

19. App Architecture (Cont.)
Broadcast Receiver
 Receive announcements and react.
 Examples of System broadcast:
 Time zone has changed
 Battery is low, and soon.
 Applications can also initiate broadcasts
 ex: Data has been downloaded
 An app can have many broadcastReceivers
 Difference between BroadcastReceiver and
the services.
o Broadcast intents delivered to all BR.
o Some Broadcast intents are sticky.

20. App Architecture (Cont.)
Content Provider
 Makes app data available to other apps by
storing it to:
o File system
o SQLite
 Implement a standard set of methods
o Enable other apps to access and store
data
 Apps cannot call methods directly
 ContentResolver object is used to
o communicate with other content
provider
o Cooperate with the provider to
manage any interprocess
communication that is involved

21. App Architecture (Cont.)
Intent
Passive data structure holding an abstract description of an operation to be
performed
 Facilitate late run-time binding between components
 All Activities, Services, and BroadcastReceivers are activated by intents.
 An intent is passed with its data to the System to start an operation, the system
finds the appropriate action and performs it.
 The primary pieces of information in an intent are:
o Action: action to be performed (ex: ACTION_VIEW, ACTION_DIAL, etc)
o Data: data to operate on (ex: person record from the database)
 Examples:
Intent i = new Intent(this, NameOfClassToTransitTo.class);
i.putExtra(“key”, “value”);
startActivity(i);

22. App Architecture (Cont.)
An intent filter declares the capabilities of its parent component — what an activity
or service can do and what types of broadcasts a receiver can handle

23. App Architecture (Cont.)
AndroidManifest.xml

24. Applications packaging
So what is delivered?
zip file (.apk)
 Java .class converted to .dex
 XML-files compressed into binary form
 manifest for app permissions
 signed with developer private key
 developer public key included
 assets packaged as is

25. Security
 Android apps run in sandboxed instances
 Linux user account per app
 Based on app permissions
 Apps are signed by developer private key
 No central authority
 why signing at all:
two sibling apps can share data (process and
userid)
 upgrade also smooth, same key

26. Other Android Features
 Open Nature
 Open Source
 Freedom of Customisability
(Custom ROM, OS Builds, Core App Replacement).
 User widgets
 Community Based Development
 Third Party App Stores
 Flash Support
 Seamless Integration with Google Stuff
 Application framework enabling reusability and replacement of App components
 SQLite for structured data storage
 Media Support
o Property-based animation and Renderscript 3D graphics.
o Support MTP and PTP protocols
 Full device encryption
o DPM policies for encrypted storage and passwords

27. Android Issues
Drawbacks:
Fragmentation
Hardware Acceleration
Development environment
Security Issue
Slow Update process
No Central Point of Control (Security, Updates, Notifications, etc).

28. Conclusions
 Android advantages outweigh its drawbacks as mentioned earlier.
 Android OS is still Consumer focused, no considerable presence in corporate
market.
 Fragmentation and Security are the two major concerns in Android.
 Development tools are evolving.
 In Future, Android might loose a bit of the share to other OS like Windows 7, but
would still be one of the top Mobile OS.
 It all depends on how Google Plays it.

29. References
 http://developer.android.com/
 http://en.wikipedia.org/wiki/Android_(operating_system)

http://www.slideshare.net/clement.escoffier/android-a-linuxbased-os-for-mobile-phone

http://lifehacker.com/5801862/top-10-awesome-android-features-that-the-iphone-doesn
 http://www.slideshare.net/atomi/android-overview
 http://androidandme.com/2012/04/opinions/the-future-of-android-in-2012/

30. Demo & Q&A