Android Architecture

Android Architecture

(1)Linux kernel:-.At the bottom of the layer is Linux- Linux 3.6 with approximately 115 patches.
This provides a level of abstraction between the device hardware and it contains all the essential hardware drivers like cameras, keypad, displays etc. This provides a level of abstraction between the device hardware and it contains all the essential hardware drivers like cameras, keypad, displays etc.
(2)Libraries:-On top of Linux kernel, there is a set of libraries including open source web browser engine WebKit, well known library libc, SQLite database which is a useful repository for storage and sharing of application. 
[a]Android Libraries:-This category encompasses those Java based libraries that are specific to android development.
[b] Android runtime:-This is the third section of architecture and available on the second layer from the bottom.This section provides a key component called Dalvik Virtual Machine which is a kind of Java virtual machine specially designed and optimized for android.##The Dalvik  VM makes use of Linux core features like memory management and multi-threading.(3)Application Framework:- This layer provides many high- level services to applications in terms of Java classes.
##Application developers are allowed to make use of these services in their applications.The Android framework includes the following key services:-
[a]Activity manager:-Controls all aspects of the application life cycle and activity stack.

[b]Content Providers:-Allows applications to publish and share data with other applications.[c]Resource manager:-Provides access to non-code embedded resources such as strings, color setting and user interface layouts.
[d]Notification manager:- Allows applications to display alerts and notifications to the user.
[e]View System:-An extensible set to views used to create application user interfaces. 
(4)Applications:- We will find all the android application at the top layer.
## we will write our application to be installed on this layer only.
## Example of such applications are contacts books, browser , games etc.