Overview
Android is a software package and Linux based operating system for mobile devices such as tablet computers and smartphones.
Android operating system is a stack of software components which is roughly divided into four main layers as shown below in the architecture diagram.
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| Android software stack |
Linux kernel and a collection of C/C++ libraries are exposed through an
application framework which manages and provides the services for the application at run time.
Understand the Architecture layers in brief.
1. Application Layer.
Application Layer the topmost layer of android architecture contains all android applications, the native applications provided with the particular Android implementation (for example web browser, contacts and email applications etc) and the third party applications installed by the user after purchasing the device.
2. Application Framework.
Android applications directly interacts with application framework. Application framework includes Android API's such as UI (User Interface), telephony, resources, locations, Content Providers (data) and package managers. It provides a lot of classes and interfaces for android application development. It also provides a generic abstraction for hardware access and manages the user interface and application resources.
Let's understand what actually framework API's do.
Activity Manager
Used to manage complete activity life cycle of applications
Content Providers
Used to manage the data sharing between two applications
Telephony Manager
Used to manages all voice calls
Location Manager
Used to manage the Locations obtained using GPS or cell tower
Resource Manager
Used to manage the different types of resources used in android app
Views
Used to construct the user interfaces for activities.
Notification Manager
Used to tell the user that something has happened in the background.
3. Libraries and Android run time
Libraries:-
It provides the different libraries useful for well functioning of android operating system. Libraries are written in java and C/C++ languages build specific for android operating system.
SQLite
It is used to access data published by content providers and includes SQLite database management classes
SSL
It is used to provide internet security
OpenGL
It is used to provide Java interface to the OpenGL/ES 3D graphics rendering API.
Media framework
It is used to provides different media codecs which allow the recording and playback of different media formats
WebKit
It is the browser engine used to display internet content or HTML content
It is used to access data published by content providers and includes SQLite database management classes
SSL
It is used to provide internet security
OpenGL
It is used to provide Java interface to the OpenGL/ES 3D graphics rendering API.
Media framework
It is used to provides different media codecs which allow the recording and playback of different media formats
WebKit
It is the browser engine used to display internet content or HTML content
FreeType
It is used for font support
Android run time.
In android run time, there are core libraries and DVM (Dalvik Virtual Machine) which is responsible to run android application. DVM is like JVM but it is optimized for mobile devices. It consumes less memory and provides fast performance.
In android run time, there are core libraries and DVM (Dalvik Virtual Machine) which is responsible to run android application. DVM is like JVM but it is optimized for mobile devices. It consumes less memory and provides fast performance.
