Android overview

14 MAY 2011 MVJ College Of Engineering

Android Overview

Badrinath Kulkarni

Member, The Bangalore Android User Group [ B.A.U.G ]

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What is Android ?

• Android is a software stack for mobile devices that includes an operating system, middleware and key applications.

• It is an open-source project from

• “Open Handset Alliance(OHA)” led by Google.Source at -

http://android.git.kernel.org/

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Open Handset Alliance(OHA)

• The Open Handset Alliance (OHA) is a business alliance of >79 firms for developing open standards for mobile devices.

• The OHA was established on 5 November 2007, led by Google.

• OHA includes mobile handset makers, application developers, mobile carriers and chip makers.

• Android, the flagship software of the alliance, is based on an open source license and competes against mobile platforms from Apple, Microsoft, Nokia, Palm, Research In Motion, Symbian, and Bada.

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History

• July 2005 : Google acquired Android Inc.

• 5 Nov 2007 :

Open Handset Alliance formed-Google, HTC, Intel, Motorola, Qualcomm , T-Mobile etc.

• Android is the first product of OHA.

• 12 Nov 2007 : OHA released a preview of the Android OHA

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Architecture

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Applications

• All applications are written using the Java language.Ex : Email Client , SMS Program , Calendar, Browser , Contacts

Component Description

Activity UI component typically corresponding to a screen.E.g. Contacts: 3 activities: View contacts, Send message, Edit contact

Service Background process without UI.Ex : Messages can be sent/received , mp3 player

Content Provider Enables applications to share dataEx : Contacts are provided to all applications.

Broadcast Receiver Responds to external events, can wake up your processEx : Phone rings, network activity established, time controlled tasks

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Application Framework

Feature Role

View System Used to build an application, including lists, grids, textboxes, buttons, and embedded web browser

Content Provider Enabling applications to access data from other applications or to share their own data

Resource Manager Providing access to non-code resources (localized string, graphics, and layout files)

Notification Manager Enabling all applications to display customer alerts in the status bar

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Libraries

Library Description

System C library

A BSD-derived implementation of the standard C system library (libc), tuned for embedded Linux-based devices

Media Libraries Based on Packet Video's Open CORE; the libraries support playback and recording of many popular audio and video formats, as well as static image files, including MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG. (Now Stagefright)

Surface Manager 

It manages access to the display subsystem and seamlessly composites 2D and 3D graphic layers from multiple applications

LibWebCore A modern web browser engine which powers both the Android browser and an embeddable web view

SGL   The underlying 2D graphics engine

3D libraries An implementation based on OpenGL ES 1.0 APIs; the libraries use either hardware 3D acceleration (where available) or the included, highly optimized 3D software

FreeType A bitmap and vector font rendering

SQLite  A powerful and lightweight relational database engine available to all applications

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Android Runtime

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Library Description

Core library Provides most of the functionality available in the core libraries of the Java language.APIs : Data Structures , Utilities , File Access , Network Access , Graphics , Etc

Dalvik Virtual Machine( DVM )

•Register-based virtual machine•Providing environment on which every Android application runs•Each Android application runs in its own process, with its own instance of the DVM.•Dalvik has been written so that a device can run multiple VMs efficiently.

Dalvik Executable(.dex) •.dex format is optimized for minimal memory footprint.

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Linux Kernel

Relying on Linux Kernel 2.6 for core system services

Memory and Process Management

Network Stack

Driver Model

Security

Providing an abstraction layer between the H/W and the rest of the S/W stack

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Thank You!

11@ iBadrinath@ iBadrinath