@2011 Mihail L. Sichitiu
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Android Introduction
Platform Overview
@2011 Mihail L. Sichitiu
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What is Android?
Android is a software stack for mobile devices that includes an operating system, middleware and key applications.
@2011 Mihail L. Sichitiu
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OHA (Open Handset Alliance)
A business alliance consisting of 47 companies to develop open standards for mobile devices
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Phones
HTC G1,
Droid,
Tattoo
Motorola Droid (X)
Suno S880
Samsung Galaxy
Sony Ericsson
@2011 Mihail L. Sichitiu
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Tablets
Velocity Micro Cruz
Gome FlyTouch
Acer beTouch
Dawa D7
Toshiba Android
SmartBook
Cisco Android Tablet
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MarketShare
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Architecture
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Android S/W Stack - Application
Android provides a set of core applications:
Email Client
SMS Program
Calendar
Maps
Browser
Contacts
Etc

All applications are written using the Java language.
@2011 Mihail L. Sichitiu
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Android S/W Stack –
App Framework
Enabling and simplifying the reuse of components
Developers have full access to the same framework APIs used by the core applications.
Users are allowed to replace components.
@2011 Mihail L. Sichitiu
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Android S/W Stack –
App Framework (Cont)
Features
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Android S/W Stack - Libraries
Including a set of C/C++ libraries used by components of the Android system
Exposed to developers through the Android application framework
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Android S/W Stack - Runtime
Core Libraries
Providing most of the functionality available in the core libraries of the Java language
APIs
Data Structures
Utilities
File Access
Network Access
Graphics
Etc
@2011 Mihail L. Sichitiu
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Android S/W Stack – Runtime (Cont)
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
@2011 Mihail L. Sichitiu
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Android S/W Stack – Runtime (Cont)
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
@2011 Mihail L. Sichitiu
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Android S/W Stack – 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