This question appears in Mumbai University > Mobile Communication and Computing subject

Marks: 10 M, 5 M

Year: May 2015, Dec 2015

Android framework

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:

1. As mentioned earlier, the Android OS is based on Linux Kernel.
2. Android uses Linux for all memory management, process management, networking and other operating systems services.
3. 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:

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

• Android Runtime:

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

• Application Framework:

1. This layer provides high level building blocks that can used for developing applications.
2. 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:

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