Android Overview

Sarwan Singh

www.SarwanSingh.com

www.android.comSession 2

Brief History 1996

The WWW already had websites with color and images

But, the best phones displayed a couple of lines of monochrome text! Wireless Application Protocol (WAP) – stripped down

HTTP for bandwidth reduction Wireless Markup Language (WML) – stripped down

HTML for content

Brief History Many issues (WAP = “Wait And Pay”)

Few developers to produce content (it wasn’t fun!) Really hard to type in URLs using the small

keyboards Data fees frightfully expensive No billing mechanism – content difficult to monetize

Other platforms emerged Palm OS, Blackberry OS, J2ME, Symbian (Nokia),

BREW, OS X iPhone, Windows Mobile

Brief History - Android 2005

Google acquires startup Android Inc. to start Android platform

Work on Dalvik VM begins 2007

Open Handset Alliance announced Early look at SDK

2008 Google sponsors 1st  Android Developer Challenge T-Mobile G1 announced SDK 1.0 released Android released open source (Apache License) Android Dev Phone 1 released

Brief History cont. 2009

SDK 1.5 (Cupcake) New soft keyboard with “autocomplete” feature

SDK 1.6 (Donut) Support Wide VGA

SDK 2.0/2.0.1/2.1 (Eclair) Revamped UI, browser

2010 Nexus One released to the public SDK 2.2 (Froyo)

Flash support, tethering SDK 2.3 (Gingerbread)

UI update, system-wide copy-paste

GingerbreadAndroid 2.3

Brief History cont. 2011

SDK 3.x (Honeycomb) Optimized for tablet support

SDK 4.0 (Ice Cream Sandwich) Virtual UI buttons

2012 SDK 4.1.1 (Jelly Bean)

Triple buffered graphics pipeline

HoneycombAndroid 3.0-3.2

Ice cream SandwichAndroid 4.0+

Jelly BeanAndroid 4.1.1

Kit KatAndroid 4.4

Brief History cont.

Distribution of Devices

http://developer.android.com/resources/dashboard/platform-versions.html

Mobile Applications What are they?

Any application that runs on a mobile device Types

Web apps: run in a web browser HTML, JavaScript, Flash, server-side components, etc.

Native: compiled binaries for the device Often make use of web services

What is Google Android?

A software stack for mobile devices that includes An operating system Middleware Key Applications

Uses Linux to provide core system services Security Memory management Process management Power management Hardware drivers

Android Architecture

More details at: http://developer.android.com/guide/basics/what-is-android.html

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Android Architecture - DVM Dalvik Virtual Machine

Providing environment on which every Android application runs Each Android application runs in its own process, with

its own instance of the Dalvik VM. Dalvik has been written such that a device can run

multiple VMs efficiently.

Register-based virtual machine

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Android Architecture - DVM Dalvik Virtual Machine (Cont)

Executing the Dalvik Executable (.dex) format .dex format is optimized for minimal memory footprint. Compilation

Relying on the Linux Kernel for: Threading Low-level memory management

Android Apps Built using Java and new SDK libraries

No support for some Java libraries like Swing & AWT Java code compiled into Dalvik byte code (.dex)

Optimized for mobile devices (better memory management, battery utilization, etc.)

Dalvik VM runs .dex files

Java for Android Android applications are developed using the

Java language. Java is a very popular programming language

developed by Sun Microsystems (now owned by Oracle).

Developed long after C and C++, Java incorporates many of the powerful features of those powerful languages while addressing some of their drawbacks.

Java for Android (Cont.) Important Features of Java

It’s easy to learn and understand It’s designed to be platform-

independent and secure, using virtual machines

It’s object-oriented Its secure (no pointers), It’s robust, multi-threaded,

distributed...

Java for Android (Cont.) Android relies heavily on these Java fundamentals. The Android SDK includes many standard Java

libraries (data structure libraries, math libraries, graphics libraries, networking libraries and everything else you could want) as well as special Android libraries that will help you develop awesome Android applications.

Setting up the Android Development Environment

Install Oracle JDK SE Setting up the ADT Bundle

Download the ADT from Google’s Android Developer Resources

Unpack the ZIP file (named adt-bundle-<os_platform>.zip) and save it to an appropriate location, such as a "Development" directory in your home directory.

Open the adt-bundle-<os_platform>/eclipse/ directory and launcheclipse

That's it! The IDE is already loaded with the Android Developer Tools plugin and the SDK is ready to go.

Development process for an Android app

http://developer.android.com/guide/developing/index.html

Building and running

ADB is a client server program that connects clients on developer machine to devices/emulators to facilitate development.

An IDE like Eclipse handles this entire process for you.

http://developer.android.com/guide/developing/building/index.html#detailed-build

Compiled resources (xml files)

Android Debug Bridge

Building and Running

Applications Are Boxed

By default, each app is run in its own Linux process Process started when app’s code needs to be executed Threads can be started to handle time-consuming

operations Each process has its own Dalvik VM By default, each app is assigned unique Linux ID

Permissions are set so app’s files are only visible to that app

Android Architecture

Publishing and Monetizing

Paid apps in Android Market, various other markets

Free, ad-supported apps in Android Market Ad networks (Google AdMob, Quattro Wireless) Sell your own ads

Services to other developers Ex. Skyhook Wireless (http://www.skyhookwireless.com/)

Contests (Android Developer Challenge) Selling products from within your app

Android Market (Google Play)

https://play.google.com/store

Has various categories, allows ratings Have both free/paid apps Featured apps on web and on phone The Android Market (and iTunes/App Store) is

great for developers Level playing field, allowing third-party apps Revenue sharing

Publishing to Google Play

Requires Google Developer Account $25 fee

Link to a Merchant Account Google Checkout Link to your checking account Google takes 30% of app purchase price

Android Design Philosophy

Applications should be: Fast

Resource constraints: <200MB RAM, slow processor Responsive

Apps must respond to user actions within 5 seconds Secure

Apps declare permissions in manifest Seamless

Usability is key, persist data, suspend services Android kills processes in background as needed

Other design principles

http://developer.android.com/design/index.html