About Android and its Architecture

The word "Android" means a Robert with Human Appearance. But in this post i will not say anything about  Robotics.

 Android is a Open Source Operating System that built on LINUX 2.6 KERNEL which provide hard core system service like SECURITY, MEMORY AND PROCESS MANAGEMENT.

Now Android captures one fourth of mobile phone market..the reason is.. its open source and it is powered by GOOGLE and more over in Android all application has equal standing i.e The third party and native application (calculator, camera, email, sms...etc.,) are written in same API libraries. All Android device offers same Operating System functionality but they differ in user interface due to OEM (Original Equipment Manufacture) for example HTC with Sense UI, Motorola with MotoBlur, and Sony Ericsson's custom UI.

All Android applications are written in java language but they are not run in J2ME. Since JVM requires a more memory like our PC, so it is not possible to do in Mobile Phones, so the android decides to use the Virtual Machine called DALVIK VIRTUAL MACHINE (DVM). The DVM is a registered-based VM that has been optimized to ensure that  multiple instance run efficiently on a single device. It relies on the Linux Kernel for threading and low memory management. 

Now jumps to Android System Architecture

• Linux Kernel :-
  Core services like hardware, process, memory, security, network and power management are handled by Linux Kernel 2.6.
• Libraries:-
  Running on top of Kernel is Libraries, it includes
  > Media library for playback of audio and video media
  > Surface manager for provide a display management
  >Graphics library that includes SGL and OpenGl for 2D and 3D graphics.
  >SQLite for native database support
  >SSL and WebKit for integrated web browser and internet security
• Android Run time:-
  
   >Core libraries:- The Android library provides the functionality available in core java library as  well as Android-Specific Library.
  >Dalvik Virtual Machine:-   The DVM is a registered-based VM that has been optimized to ensure that  multiple instance run efficiently on a single device. It relies on the Linux Kernel for threading and low memory management.
• Application framework:-
  
  The application framework provides the classes used to create an Android Applications.
  (In general meaning, The application framework is consists of software framework which is used by software developer to implementing a standard structure of an Application for a specific development, Now in Android Application Framework point of view lets take one application framework called Notification manager which is used to implement a Notification  for a SMS development)
  
  
• Application Layer:- 
  
  All application, both native and third party are built on Application layer using the Library API.
  The Applications Layer runs within the Android run time using the class and service.
  (In simple Google Chrome, Firefox, Safari are applications which runs on application layer protocol ,Likewise android application like Barcode scanner, Adobe reader which runs on Application Layer).