Mumbai University > Computer Engineering > Sem6 > Mobile Communication and Computing

Marks: 5M/10M

Year: May15, Dec 15

About Android:

• Android is a mobile operating system that is based on a modified version of Linux.
• Since 2005, the Android OS is owned by Google and distributed as open-source software under Apache license.

• With the advent of smartphone era, android has become the most popular Operating System running on Smartphones due to some of it’s features like

  • Unified Development approach
  • better storage,
  • better connectivity features (4G LTE, Wi-Fi )
  • Multi-tasking, Multi-touch,
  • Better Hardware and Media Support etc.

  The diagram above shows the architecture of the Android OS. It is basically made up of five layers as described below:

• Linux Kernel:

  • As mentioned earlier, the Android OS is based on Linux Kernel.
  • Android uses Linux for all memory management, process management, networking and other operating systems services.
  • Inside the Linux kernel, it contains all the low-level device drivers meant for the various hardware components of and Android Device.

  (Extra Info: A driver is a software which is meant to interconnect between Software System and the peripheral like camera, printer, Bluetooth, etc.)

• Libraries:

  • It contains the shared library files usually written in C or C++ and compiled for the particular architecture and the make of the phone.
  • It is preinstalled by the vendor.
  • It contains all the code that provides the main features of an Android OS.
  • For e.g., SQLite library is used for providing database support to the applications.

• Android Runtime:

  • It provides a set of core libraries that enables developers to write and develop Android apps using the Java programming language.
  • It also contains the Dalvik Virtual Machine (DVM). It is Google’s implementation of Java Virtual Machine (JVM).
  • It is specifically developed for Android to satisfy the limited memory and battery availability.
  • The Java codes are compiled and made as dalvik executable with the extension .dex .

• Application Framework:

  • This layer provides high level building blocks that can used for developing applications.
  • Some important parts of this framework include the Activity Manager that is used mainly to control the life cycle of an application. It provides a stack meant to keep track of user movement when ‘back’ button is pressed.

• Applications:

  • This is the layer that the end-user sees or works with.
  • Here the various applications are kept which include the systems apps, pre-installed factory apps, self-developed apps, apps from Play store, etc.