1. Android Introduction Based on slides made by
Mihail L. Sichitiu and Kesav Kaliyaperumal
and also from wikipedia

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

3. Android OS an open-source operating system based on the Linux kernel
designed primarily for touchscreen mobile devices such as smartphones and tablet computers
1 billion Android devices have been activated
48 billion apps have been installed

4. Phones HTC G1, Droid, Tattoo Motorola Droid (X) Sony Ericsson
Suno S880
Samsung Galaxy
@2011 Mihail L. Sichitiu

5. Tablets Velocity Micro Cruz Gome FlyTouch Acer beTouch Toshiba Android
SmartBook
Cisco Android Tablet
Dawa D7
@2011 Mihail L. Sichitiu

6. Others
Google Glasses
Portable/Car
Devices
Watches
SmartTV

7. MarketShare Feb’10 May’10 Apr’11 RIM 42.1% 41.7% 29% Apple 25.4% 24.4%
25%
Google 9%
13%
33%
Microsoft
15.1%
13.2%
7.7%
Palm
5.4%
4.8%
2.9%
Now (November 2013): 80%
@2011 Mihail L. Sichitiu

8. Android OS
Interface
Android's user interface is based on direct manipulation: using touch inputs that loosely correspond to real-world actions, like swiping, tapping, pinching and reverse pinching to manipulate on-screen objects.

9. Android OS Memory management
Android is designed to manage memory (RAM) to keep power consumption at a minimum, in contrast to desktop operating systems which generally assume they are connected to unlimited.
When an Android app is no longer in use, the system will automatically suspend it in memory – while the app is still technically "open“.

10. Android OS Memory management
Android manages the apps stored in memory automatically: when memory is low, the system will begin killing apps and processes that have been inactive for a while, in reverse order since they were last used (i.e. oldest first).
This process is designed to be invisible to the user, such that users do not need to manage memory or the killing of apps themselves.

11. Android App Priority and Processes
Android apps do not have control over their own life cycles
Aggressively manages resources to ensure device responsiveness and kills process/apps when needed
Active Process – critical priority
Visible Process – high priority
Started Service Process
Background Process – low priority
Empty process

12. Linux Kernel and Storage Management
The flash storage on Android devices is split into several partitions, such as /system for the operating system itself, and /data for user data and application installations.
In contrast to desktop Linux, Android device owners are not given root access to the operating system and sensitive partitions such as /system are read-only. However, root access can be obtained by exploiting security flaws in Android.

13. Software Stack Linux kernel Libraries Android run time
core libraries
Dalvik virtual machine
application layer
application protocol

14. Android Architecture

15. Android S/W Stack - Application
Android provides a set of core applications:
Client
SMS Program
Calendar
Maps
Browser
Contacts
Etc
All applications are written using the Java language.
@2011 Mihail L. Sichitiu

16. 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

17. Android S/W Stack – App Framework (Cont)
Features
Feature
Role
View
System
Used to build an application, including lists, grids, text boxes, 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 strings, graphics, and layout files)
Notification Manager
Enabling all applications to display customer alerts in the
status bar
Activity
Managing the lifecycle of applications and providing
a common navigation backstack
@2011 Mihail L. Sichitiu

18. 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
@2011 Mihail L. Sichitiu

19. 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

20. JVM

21. 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

22. 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

23. 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
@2011 Mihail L. Sichitiu