what is android? - bloomsburg university of …facstaff.bloomu.edu/dcoles/345/docs/what_is.pdfa...

What is Android?

Mobile Device Application DevelopmentCOMPSCI 345

Fall 2017

Android is an Operating System

● An interface between users/applications and the hardware.

Provides a high-level view of I/O devices. Provides useful abstractions: processes, memory, files...

● Resource allocator

Mediates conflicting requests for CPU time, access to devices,and other resources.

● Control program

Provides environment for safe execution of user applications. Example: prevents a process from accessing memory outside

its address space or writing to the boot sector.

Android is an Operating System

● Built on top of Linux (kernel version 3.10.49).

● Linux (written in C) handles: thread management. memory management. power management.

● Android is not (?) a Linux distribution. The kernel was modified for mobile devices. Optimized for minimal memory footprint. Does not include many standard tools and libraries.

Why Linux?

● Hardware manufacturers can develop device drivers for awell-known kernel.

● Security:

A mature open-source kernel in widespread use. Trusted by corporations and security experts. Constantly being researched, attacked, and fixed.

● Application sandbox:

Every app runs as a separate Linux process. Actually, all software above the kernel is sandboxed.

Not Just an Operating System

● “Android is an open source, Linux-based software stackcreated for a wide array of devices and form factors.”

A software stack is a set of software subsystems thatcomprise a platform for the execution of applications.

Devices: smartphones, tablets, wearables, ...

A form factor is determined by size, shape, and otherphysical characterisitcs of devices. Example: mobilephone form factors include bar, flip, and slider.

Android is a Software Stack

Hardware Abstraction LayerHardware Abstraction Layer

Native C/C++Libraries


AndroidRuntimeAndroidRuntime

Linux KernelLinux Kernel

Java API FrameworkJava API Framework

System AppsSystem Apps


● Thread management● Memory management● Power management● Drivers

usb wifi audio camera display keypad bluetooth binder (IPC) shared memory















System AppsSystem Apps● Provides standard

interfaces exposingdevice capabilities toJava API framework.

Audio

Sensors

Camera

Bluetooth

⋮








System AppsSystem Apps● Many core system

components run nativecode requiring librarieswritten in C or C++.

● Java API Frameworkexposes some of theselibraries to apps.

Libc

Webkit

Open GL ES

OpenMAX AL

Media Framework








System AppsSystem Apps● Designed to run

multiple VMs onlow-memory devices.

● Runtime librariesthat implement mostof the core Java API.








System AppsSystem Apps● The building blocks used

by app developers.

● Java classes for:

UI components

UI layouts

Activities

Resources

Notifications

Content providers

● Stored in the read-only/system/app folder.

Web browser

Calendar

Camera

Dialer

Email









⋮

Dalvik Virtual Machine

● VM for executing Android apps.

● Optimized for running multiple instances.

● Register-based. Fewer (but more complex) instructionscompared with stack-based VMs (like the JVM).



Android RuntimeAndroid Runtime

App A

Dalvik VM

App B

Dalvik VM

App C

Dalvik VM

App D

Dalvik VM


JavaCompiler

JavaCompiler

SourceCode

SourceCode

ByteCodeByteCode JVMJVM


DEXCompiler

DEXCompiler

DalvikByteCode

DalvikByteCode

DalvikVM

DalvikVM

JavaCompiler

JavaCompiler

SourceCode

SourceCode

ByteCodeByteCode JVMJVM

Android Runtime (ART)

● Successor of Dalvik for improved performance. AOT compiler. Improved garbarge collection. More debugging features.

● Runs DEX bytecode for backward compatibility.

● History: Included in 4.4 (KitKat) as alternative runtime. Replaced Dalvik entirely in 5.0 (Lollipop). Added JIT compiler with code profiling in 7.0 (Nougat).

https://source.android.com/devices/tech/dalvik/

Android Development

● In order to write apps, you will need: JDK (SE) 7 or 8 The Android SDK Android Studio

● Apps can be run in the SDK’s emulator or deployeddirectly to an attached device.

● Some knowledge of XML is needed. app configuration resource management

Using Java

● All features of Java 7 are supported.

● Supported features of Java 8: lambda expressions method references type annotations repeatable annotations (API 24 only) default and static interface methods (API 24 only)

● Google vs. Oracle: can an API be copyrighted?

https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html

https://docs.oracle.com/javase/tutorial/java/javaOO/methodreferences.html

https://docs.oracle.com/javase/tutorial/java/annotations/type_annotations.html

https://docs.oracle.com/javase/tutorial/java/annotations/repeating.html

https://docs.oracle.com/javase/tutorial/java/IandI/defaultmethods.html

Other Development Languages

● The NDK enables use of native-code languages likeC and C++, and libraries written in those languages.

● Google’s own Go programming language. A compiled, concurrent, garbage-collected, statically

typed language developed at Google. Open source. Go imports the public repository. Home FAQs Splash Article

https://golang.org/

https://golang.org/doc/faq

https://talks.golang.org/2012/splash.article

Other Development Languages

● Kotlin is now an official Android language. Resembles but improves upon Java (safer, more concise) Designed to interoperate with Java. Can use the Java Class Library. Runs on the JVM. Can be compiled to JavaScript source code. Created and developed by JetBrains. Fully supported in Android Studio.

https://kotlinlang.org/

https://www.jetbrains.com/

Android SDK

● Developer tools compiler debugger emulator

⋮● Documentation

● Sample code and tutorials

● Implementation of the Android API

Android Studio

● Google’s official IDE for Android development

● Built on top of IntelliJ IDEA (Community Edition)

World-class code editing, debugging, performancetooling, a flexible build system, and an instantbuild/deploy system all allow you to focus onbuilding unique and high quality apps.

https://developer.android.com/studio/index.html

https://www.jetbrains.com/idea/

Material Design

● A design philosophy for the look-and-feel of an appthat allows for a unified experience across platformsand device sizes.

● Three guiding pinciples: Material is the metaphor. Bold, graphic, intentional. Motion provides meaning.

https://developer.android.com/design/

Material is the Metaphor

● Inspired by paper and ink.

● Grounded in tactile reality.

● Surfaces and edges provide visual cues.

● Familiar tactile attributes suggest affordances.

● Flexibility of material creates new affordances thatsupercede laws of physics without breaking them.

● Realistic lighting shows seams, divides space, andindicates moving parts.

Bold, Graphic, Intentional

● Elements of print-based design create hierarchy,meaning, and focus. typography space scale color

● Immerses user in the experience.

● Emphasis on user actions makes core functionalityimmediately apparent and provides waypoints.

Motion Provides Meaning

● Primary user actions are inflection points thatinitiate motion, transforming the whole design.

● Objects presented without breaking continuity ofexperience, even as they transform and reorganize.

● Motion focuses attention and maintains continuity.

● Transitions efficient yet coherent.

History

2001 Google starts filing for mobile patents.

2005 Google purchases Android, Inc.

2007 Open Handset Alliance

2008 Android 1.0

2009 Android 1.5

2010 Sued by Oracle for copyright/patent infringement.

2011Acquires Motorola and 17,000 patents. Purchases 1023 patents from IBM.

History

● Google sync:

Gmail, Contacts, Calendar● Standard apps

alarm clock, dialer,launcher, gallery,calculator, settings

● App downloads and updatesthrough Android Market

Version Android 1.0

API Level 1

Release Date 09/23/2008

● Web Browser

● WiFi and Bluetooth

● Camera

● Media Player

● Instant messaging

● Text messaging

● Google Maps with Street View

History

● Map improvements

● Save attachments

● Show/hide dial pad

Version Android 1.1

API Level 2


Cupcake

● Widgets

● Pictures in contacts

Version Android 1.5

API Level 3


● Video recording/playback

● Animated screen transitions

● Auto-rotation option

● Upload to YouTube and Picassa

● Virtual keyboards with text prediction and user dictionary

Donut

● Text-to-speech engine

Version Android 1.6

API Level 4


● Expanded gesture framework

● Multlingual speech synthesis

● Integrated camera/gallery

● Select multiple photos for deletion

● Enhanced voice and text entry search

● View app screenshots in Android Market

Eclair

Version Android 2.0

API Level 5


● Live wallpapers

● Multi-touch events

● Improved Google Maps

● Tap contact photo to call

● Many new camera features

● Add multiple accounts to adevice for synchronizationof email and contacts

Version Android 2.1

API Level 7


Version Android 2.0.1

API Level 6


● Improved typing speed on virtual keyboard with smarterdictionary that uses contact names as suggestions.

Froyo

● USB tethering

● File uploads in browser app

● JavaScript V8 engine in Chrome

● Numeric and alphanumeric passwords

● Android Cloud to Device Messaging (C2DM) support

Version Android 2.2

API Level 8


● Adobe Flash support

● WiFi hotspot functionality

● Support for high PPI displays

Gingerbread

● Support for extra-large screens

● Last version to target only phones

● Oldest version still used in the wild

● Native support for new sensors (gyroscope, barometer, ...)

Version Android 2.3

API Level 9


● Multiple cameras

● Native support for VoIP

● NFC support, allowing user toread an NFC tag embedded inposter, sticker, advertisement.

Version Android 2.3.3

API Level 10


Honeycomb

Version Android 3.0

API Level 11


● Optimized for tablets

● Holographic UI

● Fragments API

● Action bar

● System bar

● USB On-The-Go

● Encrypt user data

● External keyboards

Version Android 3.1

API Level 12


Version Android 3.2

API Level 13


Ice Cream Sandwich

● Unified SDK for both tablets and phones

● Improved Holographic UI with Roboto font family

● Improved camera app with zero shutter lag, time lapsesettings, panarama mode, ability to zoom while recording

Version Android 4.0

API Level 14


● Photo editor

● Face Unlock

● Customizable launcher

● Improved voice integrationVersion Android 4.0.3

API Level 15


Jelly Bean

Version Android 4.1

API Level 16


● Smoother UI

● Multichannel audio

● Camera improvements

● Expandable notifications

● Lock screen improvements

● Multi-user support on tablets

● RTL languages supported

● Open GL ES 3.0 support

Version Android 4.2

API Level 17


Version Android 4.3

API Level 18


KitKat

● Wearable extensions

● Wireless printing

● Android Runtime (experimental)

● New framework for UI transitions

Version Android 4.4

API Level 19


● NFC host card emulation,enabling device to replacesmart cards

● Storage Access Framework

● UI updates for Google MapsVersion Android 4.4W

API Level 20


Lollipop

● Support for 64-bit CPUs

● Open GL ES 3.1 on supported GPU configurations

● 15 new languages: Basque, Bengali, Burmese, Chinese(Hong Kong), Icelandic, Kannada, Kyrgyz, Macedonian,Malayalam, Marathi, Nepali, Sinhala, Tamil, and Telugu

Version Android 5.0

API Level 21


● ART

● Tap and Go

● Project Volta

● Flashlight app

● Material Design

Version Android 5.1

API Level 22


Marshmallow

● Doze mode

● Native fingerprint reader support

● MIDI support for musical instruments

● App permissions now granted at runtime

● Automatic full backup and restore for apps

● Contextual support from keywords within apps

Version Android 6.0

API Level 23


Nougat

● Daydream virtual reality platform

● Picture-in-picture support for Android TV

● New JIT compiler with code profiling to ART

● Another system partition for seamless system updates

Version Android 7.0

API Level 24


● Ability to screen zoom

● Multi-window support

● Vulcan 3D rendering API

● Unicode 9.0 emoji supportVersion Android 7.1

API Level 25


Usage (April 2017)

Version Share

Lollipop 32%

Marshmallow 31%

KitKat 20%

JellyBean 10%

Nougat 5%

Ice Cream Sandwich 1%

Gingerbread 1%

Popularity in 2017

● 1,000,000 new users every day

● 1,000,000,000 active users daily

● 2,000,000,000 active users monthly

● 87.5% of global smartphone market share

● Largest installed base of any mobile platform

what is android? - bloomsburg university of …facstaff.bloomu.edu/dcoles/345/docs/what_is.pdfa...

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