Android File

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INTRODUCTION

World is contracting with the growth of mobile phone

technology. As the number of users is increasing day by day,facilities are also increasing. Starting with simple regular

handsets which were used just for making phone calls, mobiles

have changed our lives and have become part of it. Now they

are not used just for making calls but they have innumerable

uses and can be used as a Camera , Music player, Tablet PC,

T.V. , Web browser etc . And with the new technologies, new

software and operating systems are required.

Operating Systems have developed a lot in last 15 years.

Starting from black and white phones to recent smart phones

or mini computers, mobile OS has come far away. Especially for

smart phones, Mobile OS has greatly evolved from Palm OS in

1996 to Windows pocket PC in 2000 then to Blackberry OS andAndroid.


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Android is a Linux-based operating system designed primarily

for touchscreen mobile devices such as smartphones and tabletcomputers, developed by Google in conjunction with the Open

Handset Alliance. Initially developed by Android Inc, whom

Google financially backed and later purchased in 2005,Android

was unveiled in 2007 along with the founding of the Open

Handset Alliance, a consortium of 86 hardware, software, and

telecommunication companies devoted to advancing open

standards for mobile devices.

Google releases the Android code as open source, under the

Apache License .The Android Open Source Project (AOSP), led

by Google, is tasked with the maintenance and further

development of Android. Additionally, Android has a large

community of developers writing applications ("apps") that

extend the functionality of devices, written primarily in a

customized version of Java.They are available for download

through Google Play or third-party sites. In September 2012,

there were more than 675,000 apps available for Android, and

the estimated number of applications downloaded from Google

Play was 25 billion.

The first Android-powered phone was sold in October 2008 ,

and by the end of 2010 Android had become the world'sleading smartphone platform, overtaking Symbian which held

its record for years .It had a worldwide smartphone market

share of 68% at the second quarter of 2012,and as of Q3 2012,


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there were 500 million devices activated and 1.3 million

activations per day.

HISTORY

Android Inc. was founded in Palo Alto, California in October

2003 by Andy Rubin (co-founder of Danger), Rich Miner (co-

founder of Wildfire Communications, Inc.),Nick Sears (once VP

at T-Mobile), and Chris White (headed design and interface

development at WebTV)to develop, in Rubin's words

"...smarter mobile devices that are more aware of its owner's

location and preferences."

Google acquired Android Inc. on August 17, 2005, making it a

wholly owned subsidiary of Google. Key employees of Android

Inc., including Rubin, Miner and White, stayed at the company

after the acquisition .Not much was known about Android Inc.

at the time, but many assumed that Google was planning to

enter the mobile phone market with this move .At Google, theteam led by Rubin developed a mobile device platform

powered by the Linux kernel. Google marketed the platform to

handset makers and carriers on the promise of providing a

flexible, upgradable system. Google had lined up a series of

hardware component and software partners and signaled to

carriers that it was open to various degrees of cooperation on

their part.

Speculation about Google's intention to enter the mobile

communications market continued to build through December

2006.Reports from the BBC and The Wall Street Journalnoted


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that Google wanted its search and applications on mobile

phones and it was working hard to deliver that. Print and online

media outlets soon reported rumors that Google was

developing a Google-branded handset. Some speculated that asGoogle was defining technical specifications, it was showing

prototypes to cell phone manufacturers and network

operators. In September 2007, InformationWeekcovered an

Evalueserve study reporting that Google had filed several

patent applications in the area of mobile telephony.

On November 5, 2007, the Open Handset Alliance, a

consortium of technology companies including Google, device

manufacturers such as HTC and Samsung, wireless carriers such

as Sprint Nextel and T-Mobile, and chipset makers such as

Qualcomm and Texas Instruments, unveiled itself, with a goal

to develop open standards for mobile devices. That day,

Android was unveiled as its first product, a mobile device

platform built on the Linux kernel version 2.6.The first

commercially available phone to run Android was the HTC

Dream, released on October 22, 2008.

In 2010, Google launched its Nexus series of devices - a line

smartphones and tablets running the Android operating

system, and built by a manufacturer partner. HTC collaborated

with Google to release the first Nexus smartphone , the Nexus

One, in early 2010. The series has since been updated with

newer devices, such as the Galaxy Nexus phone and Nexus 7

tablet , made by Samsung and Asus respectively. Google

releases the Nexus phones and tablets to act as their flagship


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Android devices, demonstrating Android's latest software and

hardware features.

ARCHITECTURE

Fig.1 : Android OS Architecture

The Android OS can be referred to as a software stack of

different layers, where each layer is a group of several program

components. Together it includes operating system,

middleware and important applications. Each layer in thearchitecture provides different services to the layer just above

it.

Linux Kernel


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The basic layer is the Linux kernel. The whole Android OS is

built on top of the Linux 2.6 Kernel with some further

architectural changes made by Google. It is this Linux that

interacts with the hardware and contains all the essentialhardware drivers. Drivers are programs that control and

communicate with the hardware. For example, consider the

Bluetooth function. All devices have a Bluetooth hardware in

them. Therefore the kernel must include a Bluetooth driver to

communicate with the Bluetooth hardware. The Linux kernel

also acts as an abstraction layer between the hardware and

other software layers. Android uses the Linux for all its corefunctionality such as Memory management, process

management, networking, security settings etc. As the Android

is built on a most popular and proven foundation, it made the

porting of Android to variety of hardware, a relatively painless

task.

Libraries

The next layer is the Androids native libraries. It is this layer

that enables the device to handle different types of data. These

libraries are written in c or c++ language and are specific for a

particular hardware.

Some of the important native libraries include the following:

Surface Manager: It is used for compositing window managerwith off-screen buffering. Off-screen buffering means you

cannot directly draw into the screen, but your drawings go to

the off-screen buffer. There it is combined with other drawings


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and form the final screen the user will see. This off screen

buffer is the reason behind the transparency of windows.

Media framework: Media framework provides different mediacodecs allowing the recording and playback of different media

formats.

SQLite : SQLite is the database engine used in android for datastorage purposes.

WebKit: It is the browser engine used to display HTML content.

OpenGL: Used to render 2D or 3D graphics content to thescreen.

Android Runtime

Android Runtime consists of Dalvik Virtual machine and Core

Java libraries.

Dalvik Virtual Machine:

It is a type of Java Virtual Machine(JVM) used in android

devices to run apps and is optimized for low processing power

and low memory environments. Unlike the JVM, the Dalvik

Virtual Machine doesnt run .class files, instead it runs .dex files.

.dex files are built from .class file at the time of compilation and

provides higher efficiency in low resource environments. TheDalvik VM allows multiple instance of Virtual machine to be

created simultaneously providing security, isolation, memory

management and threading support. It is developed by Dan

Bornstein of Google.


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Core Libraries:Android includes a set of core libraries that provides most of

the functionality.

Application Framework

These are the blocks that our applications directly interact with.

These programs manage the basic functions of phone like

resource management, voice call management etc.

Important blocks of Application framework are:

Activity Manager: Manages the activity life cycle ofapplications.

Content Providers: Manage the data sharing betweenapplications.

Telephony Manager: Manages all voice calls. We use telephony

manager if we want to access voice calls in our application.

Location Manager: Location management, using GPS or celltower.

Resource Manager: Manage the various types of resources weuse in our Application.

ApplicationsApplications are the top layer in the android architecture and

this is where our applications are going to fit. Several standard

applications come pre-installed with every device, such as:


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SMS client app Dialer Web browser Contact manager

As a developer we are able to write an app which replaces any

existing system app. That is, we are not limited in accessing any

particular feature. We are practically limitless and we can do

whatever we want to do with the android. Thus Android is

opening endless opportunities to the developer.

FEATURES

Handset layouts : The platform is adaptable to larger, VGA, 2D

graphics library, 3D graphics library based on OpenGL ES 2.0

specifications, and traditional smartphone layouts.

Storage: SQLite, a lightweight relational database, is used for

data storage purposes.

Connectivity : Android supports connectivity technologies

including GSM/EDGE, IDEN, CDMA, EV-DO, UMTS, Bluetooth,

Wi-Fi, LTE, NFC and WiMAX.

Messaging : SMS and MMS are available forms of messaging,

including threaded text messaging and Android Cloud To DeviceMessaging (C2DM) and now enhanced version of C2DM,

Android Google Cloud Messaging (GCM) is also a part of

Android Push Messaging service.


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Multiple language support: Android supports multiple

languages.

Web browser:The web browser available in Android is based on

the open-source WebKit layout engine, coupled with Chrome's

V8 JavaScript engine. The browser scores 100/100 on the Acid3

test on Android 4.0.

Java support:While most Android applications are written in

Java, there is no Java Virtual Machine in the platform and Java

byte code is not executed. Java classes are compiled into Dalvikexecutables and run on Dalvik, a specialized virtual machine

designed specifically for Android and optimized for battery-

powered mobile devices with limited memory and CPU. J2ME

support can be provided via third-party applications.

Media support : Android supports the following

audio/video/still media formats: WebM , H.263, H.264, AAC,

HE-AAC (in 3GP or MP4 container), MPEG-4 SP, AMR, AMR-WB

(in 3GP container), MP3, MIDI, Ogg Vorbis, FLAC, WAV, JPEG,

PNG, GIF, BMP, WebP.

Additional hardware support: Android can use video/still

cameras, touchscreens, GPS, accelerometers, gyroscopes,barometers, magnetometers, dedicated gaming controls,

proximity and pressure sensors, thermometers, accelerated 2D

bit blits (with hardware orientation, scaling, pixel format

conversion) and accelerated 3D graphics.


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Multi-touch:Android has native support for multi-touch which

was initially made available in handsets such as the HTC Hero.

The feature was originally disabled at the kernel level . Google

has since released an update for the Nexus One and the

Motorola Droid which enables multi-touch natively.[9]

Bluetooth: Supports A2DP, AVRCP, sending files (OPP),

accessing the phone book (PBAP), voice dialing and sending

contacts between phones. Keyboard, mouse and joystick (HID)

support is available in Android 3.1+, and in earlier versions

through manufacturer customizations and third-party

applications.

Video calling:Android does not support native video calling, but

some handsets have a customized version of the operating

system that supports it, either via the UMTS network (like the

Samsung Galaxy S) or over IP. Video calling through Google Talkis available in Android 2.3.4 and later. Gingerbread allows

Nexus S to place Internet calls with a SIP account. This allows

for enhanced VoIP dialing to other SIP accounts and even

phone numbers. Skype 2.1 offers video calling in Android 2.3,

including front camera support. Users with the Google+

android app can video chat with other google+ users throughhangouts.

Multitasking:Multitasking of applications, with unique handling

of memory allocation, is available.
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Accessibility:Built in text to speech is provided by Talk back for

people with low or no vision. Enhancements for people with

hearing disabilities is available as is other aids.

Voice based features:Google search through voice has been

available since initial release.Voice actions for calling, texting,

navigation, etc. are supported on Android 2.2 onwards.As of

Android 4.1, Google has expanded Voice Actions with the ability

to talk back and read answers from Google's Knowledge Graph

when queried with specific commands.The ability to control

hardware has not yet been implemented.

Tethering:Android supports tethering, which allows a phone to

be used as a wireless/wired Wi-Fi hotspot. Before Android 2.2

this was supported by third-party applications or manufacturer

customizations.

Screen capture:Android supports capturing a screenshot by

pressing the power and volume-down buttons at the same

time.Prior to Android 4.0, the only methods of capturing a

screenshot were through manufacturer and third-party

customizations or otherwise by using a PC connection (DDMS

developer's tool). These alternative methods are still available

with the latest Android.

External storage:Most Android devices include microSD slot

and can read microSD cards formatted with FAT32, Ext3 or Ext4

file system. To allow use of high-capacity storage media such as


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USB flash drives and USB HDDs, many Android tablets also

include USB 'A' receptacle. Storage formatted with FAT32 is

handled by Linux Kernel VFAT driver, while 3rd party solutions

are required to handle other popular file systems such as NTFS,

HFS Plus and exFAT.

Android Versions

History

Android versions history involves the versions updates from 1.0

till date. Here is the list of different Android version with their

releasing date:-

1. Android 1.0 -Release Date: September 23, 2008

2. Android 1.1 -Release Date: February 9, 2009

3. Android 1.5 CupcakeRelease Date: April 30, 2009

4. Android 1.6 Donut -Release Date: September 15, 2009

5. Android 2.0/2.1 clairRelease Date: October 26, 2009

6. Android 2.2 FroyoRelease Date: May 20, 2010

7. Android 2.3 Gingerbread -Release Date: December 6, 2010

8. Android 3.0 Honeycomb -Release Date: February 22, 2011

9. Android 4.0 Ice Cream Sandwich-Release Date: October 19,2011


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10. Android 4.1 Jelly Bean -Release Date: July 9, 2012.

The pre-release versions of Android were dubbed Astro and

Bender, but these names could not ultimately be used fortrademark reasons. The most recent update to the Android OS

was Jelly Bean v4.1, which was announced in June 2012, and

was released into the Android Open Source Project on July 9,

2012.

Android 1.5 Cupcake

Cupcake was the first major overhaul of the Android OS .

Major Features:

Uploading videos to YouTube and pictures to Picasadirectly from the phone.

New widgets and folders that canpopulate the Home screens.

Bluetooth A2DP support. Ability to record and watch videos

through camcorder mode.

A new soft-keyboard with text-prediction.

Animated screen transitions.Android 1.6-Donut

Major Features:


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An integrated camera, camcorder, and gallery interface. Gallery now enables users to select

multiple photos for deletion.

Updated Voice Search, with fasterresponse and deeper integration with

native applications, including the

ability to dial contacts.

Updated search experience to allowsearching bookmarks, history,

contacts, and the web from the home screen.

Updated technology support for CDMA/EVDO, 802.1x,VPNs, and a text-to-speech engine.

Support for WVGA screen resolutions. Speed improvements in searching and camera

applications. Gesture framework and GestureBuilder development tool. Google free turn-by-turn navigation.

Android 2.0/1-Eclair

Major Features:

Optimized hardware speed Support for more screen sizes and resolutions New Browser UI and HTML5 support New Contacts List Microsoft Exchange support


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MotionEvent class enhanced to track multi-touch events Bluetooth 2.1 Improved Google Maps 3.1.2 Built in flash support for Camera Digital Zoom Live Wallpapers

Android 2.2-Froyo

Major Features:

Android OS speed, memory, and performanceoptimizations

Application speed improvements courtesy of JITimplementation

Integration of Chrome's V8 JavaScript engine into theBrowser application

Increased Microsoft Exchange support (security policies,auto-discovery, GAL look-up, calendar synchronization,

remote wipe) Improved application launcher with shortcuts to Phone

and Browser applications.

USB tethering and Wi-Fi hotspotfunctionality

Updated Market application withbatch and automatic update

features

Quick switching betweenmultiple keyboard languages and their dictionaries.


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Voice dialling and contact sharing over Bluetooth Browser can now display animated GIFs Support for installing applications to the expandable

memory Adobe Flash 10.1 supportAndroid 2.3-Gingerbread

Major Features:

Support for WebM video playback. Support for Near Field Communication

(NFC).

Multi touch software keyboard. Support for Extra Large screen sizes and

resolution.

Android 3.0-Honeycomb

Major Features:

Optimized tablet support with anew user interface.

3D desktop. Video chat and Gtalk support.


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Android 4.0-Ice Cream Sandwich

Major Features:

Refined, evolved UI. Home screen folders and favorites tray. Resizable widgets.

New lock screen actions. Quick responses for incoming calls. Swipe to dismiss notifications,tasks,and browser tabs.

Improved text-input and spell checking.

Powerful voice input engine. Live Effects for transforming video. Rich and versatile camera capabilities.

Android 4.1-Jelly Bean

Major Features:

Faster,smoother,more responsive. Enhanced accessibility. Resizable app widgets. Simplified task navigation.


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More support for different languages.

Improvements in text input. Transitions to Lights Out and Full Screen Modes. New types of remoteable views. Live wallpaper preview. Higher-resolution contact photos.

Android Application Life CycleIn Android, the applications are run as a separate

Linux process. So the application lifecycle is closely

related to the process lifecycle. The application

process lifecycle is handled by the system depending

on the current system memory state.

In case of low memory, the Android system kills some

less important process. The process importance is

decided depending on the state of the process

components.


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The process types depending on the importance areas follows :-

1. Foreground process:- A foreground process is theapplication process with which the user is currently

interacting. The process is considered to be

foreground if its Activity is at the top of the Activity

stack or its Service is executing callback functions like

onCreate(), onStart() or onDestroy() methods.

2. Visible Process:- A visible process is the processwhich has an Activity visible to the user (

3. Service Process:- Service process contains a Servicefor which startService method is called and the

service is running.

4. Background Process:- The background processdoes not have any visible activities to the user.

5. Empty Process:- Empty process is the one thatdoes not have any active application components.

These processes are kept on for caching purpose.

It is important that application developersunderstand lifecycle of the application process. Not

using these correctly can result in the system killing

the applications process while it is doing important

work.


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Multithreading in android

A Thread is a concurrentunit of execution .It is a light-weight

process.The "Main" Thread is created when the execution foran application starts. Typically, there are several others for

housekeeping. Multiple threads can exist within the same

process and share memory resources. Execution of thread is

fast as compared to process.

There are basically two main ways of having a Thread execute

application code:

1. Create a new class that extendsThread and overrideits run() method.

2.Create a new Threadinstance passing to it a Runnableobject.

In both cases, the start()method must be called to actuallyexecute the new Thread.

Advantages of Multi-Threading1. Threads sharethe process' resourcesbut are able to executeindependently.

2. Applications responsibilitiescan be separatedmain thread runs UI, and

slow tasks are sent to background threads.3. Threading provides an useful abstraction of concurrent

execution.


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4. A multithreaded program operates fasteron computersystems that have multiple CPUs.

Interaction between Android threads is accomplished using(a) a main thread Handler object and

(b) posting Runnableobjects to the main view.Permissions in Android

Android provides many types of permissions. Linux isolates

applications from each other and from the system. Android

gives each package a distinct Linux user ID. The identity remainsconstant for the duration of the package's life on that device.

Each application runs with a distinct system identity.There are

many permissions which are provided by Linux. This includes

reading or writing the user's private data , reading or writing

another application's files, performing network access, keeping

the device awake, etc.

Services Permission: Services includes calling and textingtypes permission. It could cost you money by using minutes or

sending text messages at your going rate. This would mostly be

used by a messaging or social media widget that communicates

on your behalf, like dialing back to someone who just sent you

a text. The widget could send a text message to a number that

would bill you for a text, or subscribe you to some servicewith a continuing monthly fee that is automatically billed to

your credit card. The kernel is solely responsible for sandboxing

applications from each other.


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Phone Call Permission :- Phone Call permission provides piracycontrols and authentication to a specific device. Phone call

permission includes the ability of the widget to read phone

state and identity. The widget can detect when you are on thephone, turn on a voice recorder, record your conversation, and

send the recorded data to someone else.

Network and internet Permission : This Network Permissioncreate or change either a Bluetooth or Wi-Fi network

connection. Full internet access will be necessary for anywidget that needs to transfer data onto or off the device, like

file synch and backup widgets. A video application might

connect to Bluetooth headphones. An audible text message

app might auto-connect to a Bluetooth headset.

Hardware Permission:- Hardware permission provides any

types of hardware permission like as camera, take pictures etc.A game or other widget can use phone vibration as feedback.

An email or text message widget can use the vibration for

notification. The risk is really limited.

System Tools Permission This includes a series of more

refined permissions that control some aspect of your phones

basic settings. The risk is that an approved widget could change

these settings without your interaction, and potentially prevent

you from observing a notification.


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Security in Android Operating System

Introduction

Android is a modern mobile platform that was designed to be

truly open. Android applications make use of advanced

hardware and software, as well as local and served data,

exposed through the platform to bring innovation and value to

consumers. To protect that value, the platform must offer an

application environment that ensures the security of users,

data, applications, the device, and the network.

Securing an open platform requires a robust security

architecture and rigorous security programs. Android was

designed with multi-layered security that provides the flexibility

required for an open platform, while providing protection for

all users of the platform.

Android was designed with developers in mind. Security

controls were designed to reduce the burden on developers.

Security-savvy developers can easily work with and rely on

flexible security controls. Developers less familiar with security

will be protected by safe defaults.

Android was designed with device users in mind. Users are

provided visibility into how applications work, and control over

those applications. This design includes the expectation that

attackers would attempt to perform common attacks, such as

social engineering attacks to convince device users to install


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malware, and attacks on third-party applications on Android.

Android was designed to both reduce the probability of these

attacks and greatly limit the impact of the attack in the event it

was successful.

Android Platform Security Architecture

Android seeks to be the most secure and usable operating

system for mobile platforms by re-purposing traditional

operating system security controls to:

Protect user data Protect system resources (including the network) Provide application isolation

To achieve these objectives, Android provides these key

security features:

Robust security at the OS level through the Linux kernel Mandatory application sandbox for all applications Secure interprocess communication Application signing Application-defined and user-granted permissions.

Advantages of Android Operating System1.Android can Run Multiple Apps at the Same Time.

2. Android keeps information visible on your homescreen.Android has is a customizable home screen

which keeps active widgets right at your fingertips,

always accessible and always visible without having


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to launch an application first.

3. Android has a better application market compare

to Apples App because Apples App store has over180,000 applications, while the Android Marketplace

has only just broken the 50,000 mark

4.Android gives you better notifications comparee toiPhone beacuse iPhone has some trouble with

notifications. Because its restricted to pop-up

notifications, it can only handle one at a time

6. Android is Hardware independent.

7. Android lets you install custom ROMs.

8. You can change your settings faster in Android.iPhone users are stuck digging around in the system

settings every time they want to use the internet or a

Bluetooth device. Android lets you use widgets to

manage your settings directly from your home

screen.

9. Android does Google and Social Integration but TheiPhone can do this only through use of third party

apps, and is nowhere near as seamless to use as the

Android alternative.

10. Android gives you more options to fit your


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budget. Of course these are lower end Android

devices, but they are still comparable in performance

to the iPhone 3GS.

11. Innovative products like the location-awareservices, location of a nearby convenience store etc.,

are some of the additive facilities in Android.

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