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Android O/S

Shengying Liu Wenqian Tao Grant Trudel

Android O/S

• Grant : History, Features, Applications • Wenqian : Application Framework,

Hardware, Components • Shengying Liu :Libraries, Runtime, Kernel

Android O/S - HistoryAndroid, INC October 2003

Andy Rubin Rich Miner Nick Sears Chris White

Co-founder of Danger

Co-founder of Wildfire Communications

Once a VP at T-Mobile

WebTV head of design and interface development

Android

Android O/S - History

To develop “smarter mobile devices that are more aware of its owner's location and preferences” (Andy Rubin)

Digital Cameras

Smartphones

`

$10,000

Steve Perlman


August 17, 2005


“Sooner”

InformationWeekSeptember 2007


• November 5, 2007

Open Handset Alliance

Android O/S

October 2008 HTC Dream


• 2010 – Nexus devices running Android • HTC + Google produce Nexus One • Nexus devices demonstrate latest Android

features


• March 13, 2013

Andy RubinSundar Pichai

Chrome O/S

Android O/S - HistoryMobile market share (Apr 10,

2013)

0.030.08

0.38

0.01

0.24

0.26

Android 4.1 (Jelly Bean)Android 4.0.x (ICS)Android 3.0-3.2 (Honeycomb)Android 2.3 (Gingerbread)Android 2.2 (Froyo)Android 2.1 (Éclair)

Source: http://www.nomtek.com/mobile-market-share-and-statistics-for-ios-android-and-other/

Android O/S - Features

• General • Connectivity • Media • Hardware Support • Other

Android O/S – FeaturesGeneral

• Messaging – SMS & MMS – Threaded text messaging – Android Cloud to Device Messaging (C2DM) – Google Cloud Messaging (GCM)

• Web browser – Based on Blink (previously WebKit)

layout engine – Chrome’s V8 JavaScript – Scores 100/100 on Acid3 test on version 4.0

Android O/S – FeaturesGeneral

• Voice based features • Multi-touch • Multitasking • Screen capture • Video calling • Multiple language support • Accessibility – Text to speech – Enhancements for those with hearing difficulties

Android O/S – FeaturesConnectivity

• Android supports:

GSM/EDGE Wi-Fi

Bluetooth LTE

CDMA EV-DO

UMTS NFC

IDEN WiMAX


• Bluetooth – Voice dialing – Sending contacts – Sending files (OPP) – Accessing phone book (PBAP) – A2DP (multimedia audio streaming) – AVRCP (remote control audio/video) – Keyboard, mouse, and joystick


• Tethering – Allows a phone to be used as a wireless or wired

Wi-Fi hotspot

Android O/S – FeaturesMedia

• Streaming media support – RTP/RTSP streaming – HTML progressive download (HTML5 <video> tag) – Adobe Flash streaming & HTTP dynamic

streaming (Flash plugin) – Apple HTTP Live Streaming (RealPlayer for

Android) since 3.0

Android O/S – FeaturesMedia

Android supports these audio / video / still media formats

WebM H.263 H.264 AAC HE-ACC

MPEG-4 SP AMR AMR-WB MP3 MIDI

Ogg Vorbis FLAC WAV JPEG PNG

GIF BMP WebP

Android O/S – FeaturesMedia – External Storage

• MicroSD slot – Can read FAT32, Ext3, Ext4 file system files

• Many devices use USB ‘A’ receptacle

File System Method of Reading

FAT32 Linux Kernel VFAT driver

Other 3rd

Android O/S – FeaturesHardware Support

• Still or video cameras • Touchscreens • GPS • Accelerometers – Measures g-force

• Gyroscopes – Measures orientation

• Barometers – Measures atmospheric pressure

Android O/S – FeaturesHardware Support

• Magnetometers –magnetization / magnetic fields

• Gaming controls • Proximity & pressure sensors • Thermometers • Accelerated 2D bit blits (combining bitmaps

into a single raster operator) • Accelerated 3D graphics

Android O/S - Applications

• Apps written in Java using Android SDK • SDK includes – Debugger – Software libraries – Emulator – Documentation – Sample code – Tutorials


• Official IDE is Eclipse using the Android Development Tools (ADT) plugin

• Also available: – a Native development Kit (for C/C++) – Google App Inventor (for novice programmers) – Various cross platform mobile web app

frameworks


• January 2014: Apache Cordova unveiled by Google – Framework for porting Chrome HTML 5 apps

wrapped in a native app shell • Google Play Store = the primary app store

installed on Android devices – Allows users to browse, download, and update

apps published by Google & 3rd party developers

Android O/S – Applications3rd Party Marketplace

• Amazon Appstore • GetJar • SlideMe • F-Droid – Only provide apps distributed under free & open

source licenses

Android Application Framework

Main Functions

Task & Activity & Process

Activity

contentProvider

Activity

service

Activity Activity

contentProvider

service

task

APK package APK package

process

processprocess

Activities are…• a concrete class in the API

• an encapsulation of a particular operation

• run in the process of the APK which install them

• managed as an activity stack

Tasks are…• more of a notion than an concrete API entity

• a collection of related Activities

• capable of spanning multiple processes

• associated with their own UI history stack

• what users on other platforms know as “applications”

• associated with their own UI history stack

Activity Managerstarting

running

pausedstopped

destroyed

onCreate()!onStart()!onRestoreInstanceState()!onResume()

onSaveInstanceState()!onPause()

onResume()

onSaveInstanceState() onStop()

onDestroy() or

<process killed>

<process killed>

3)onResume()!2)onStart()!1)onRestart()

System Libraries

Surface Manager

Graphics Libraries

Media Framework

Free Type

Main Functions

SSL

SQLite

WebKit

(Open GL|ES, SGL) are two core graphics libraries

contains all of the codecs that are required for multimedia experience

used for display management

used to render the fonts

used for internet security

provide database support

opensource browser engine

Libraries Overview

• Type: C/C++ standard library • Platform: x86, x86-64, ARM, ARM64, MIPS, MIPS64 • GOAL: light weight, abandon the trivia features of standard library • Features: small size, faster speed • Implementation: Java Native Interface(JNI) Android Native

Development Kit (NDK)

JNI General Workflow

Android NDK Application

Android is not LinuxWindowing system :!! X11! ! GTK!! ! Pango!!Graphic :!! Cairo! ! ! ! Skia!!GNU C :!! glibc ! ! ! ! Bionic!!Multimedia :!! ALSA,ffmpeg!! ! ! ! opencore

Android = Android Runtime + Linux Kernel

Linux Device Driver

Memory!Manager

Process!Manager

Androidism Driver

Logger

Binder

Alarm

Low Memory Killer

Other

Linux Kernel

HAL Application!Component UI

Java Runtime Framework

Dalvik Virtual Machine

C/C++ Runtime Framework

Android Runtime

…

Logger

log_main!! ! Any events!!

log_events!! ! System hardware events!!

log_radio!! ! Wireless events!!

log_system!! ! System software events

Access the logs of the system and app.

BinderWhat is Binder?

Process 1 Process 2!

Activity Service!

OR

Binder

Client Service User Space

Kernel Space

Service !Manager

Binder Driver!/dev/binder

Application

System

open ioctl open ioctlopen ioctl

IPC

Binder

Service Service Manager

String void*… …… …… …

Service ListRegister

User ProcessService manager proxy Service Address

get service manager proxy

ServiceManagerProxy.GetService()

Service proxy

Binder

Binder Entity

BpBinder

HAL(Hardware Abstract Layer)

A Good Example

Android HALWhat is HAL?

An abstract layer that capsulated the kernel drivers !and provides API to the upper layer.

Framework & Applications

External Libraries & Runtime

Linux Device Driver

HAL (libhardware)

Sensor!Stub! Stub! Stub!

HAL (libhardware)

User Space

Kernel Space

Apache License!!Control the parameters and processes

GNU License!!Hardware access logic

Dalvik Virtual Machine

Java Virtual Machine Dalvik Virtual Machine

Instruction Set Java Bytecode!(Stack Based)

Dalvik Bytecode!(Memory Based)

File Format .class file!(one file,one class)

.dex file!(one file,many classes)

Java Virtual Machine VS Dalvik Virtual Machine

Thank you !

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