22-12-2010, 11:27 AM
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INTRODUCTION
Android is a software stack for mobile devices that includes an operating system, middleware and key applications.Android is a software platform and operating system for mobile devices based on the Linux operating system and developed by Google and the Open Handset Alliance.
Google Acquires Android Inc:
In July 2005, Google acquired Android Inc,
which was a small startup company based
in Palo Alto.
Open Handset Alliance Founded:
On 5 November 2007, the Open Handset Alliance was formed.
Google, HTC, Intel, Motorola, Qualcomm, T-Mobile, Sprint Nextel and NVIDIA and many more were members and Android was released to market as an Open Source OS.
What makes Android special?
A truly open, free development platform
based on Linux and open source.
A component-based architecture inspired by Internet mash-ups. Parts of one application can be used in another.
Automatic management of the application life cycle. Programs are isolated from each other by multiple layers of security, provide system stability.
High quality graphics and sound. Uses OpenGL for graphics and supports MP3, MP4 etc for audio and videos.
Linux Kernel:
Android Architecture is based on Linux 2.6
kernel. Manage security, memory management, process management, network stack.
CDMA and GPRS network support
Bluetooth 1.2 and Wi-Fi support
Digital audio support for mp3 and other formats
Support for Linux and other third-party operating systems
Java hardware acceleration and support for Java applications
Qcamera up to 6.0 megapixels
gpsOne – solution for GPS
and lots of other.
Libraries :
Native libraries written in C/C++,
which are responsible for stable performance.
Media Libraries - based on PacketVideo's OpenCORE; the libraries support playback and recording of many popular audio and video formatslike MPEG4, MP3, JPG, and PNG.
Surface Manager – Responsible for displaying 2D and 3D graphic layers from multiple applications .
LibWebCore - a modern web browser engine which powers both the Android browser and an embeddable web view.
3D libraries - an implementation based on OpenGL ES 1.0 APIs; the libraries use hardware 3D acceleration.
SQLite - a powerful and lightweight relational database engine available to all applications
Android Runtime:
Dalvik Virtual Machine.
Android gives an integrated tool “dx”, which
converts byte code from .jar to .dex file which is
much more efficient.
Designed for Android running with limited battery, CPU, memory and data storage.
As the result, it is possible to have multiple instances of Dalvik virtual machine running on the single device at the same time.
Application Framework:
Written in Java language. It is a toolkit that all
applications uses and are developed.
The Activity Manager manages the life circle of the applications and provides a common navigation back stack for applications
The Package Manager keeps track of the applications, which are installed in the device.
Telephony Manager contains of a set of API necessary for calling applications.
Content Providers was built for Android to share a data with other applications
The View System generates a set of buttons and lists used in UI.
Application Layer:
Here we have all the applications, which are used by the final user.
Application Building Blocks:
Android application is a collection of
components, of various kinds.
The major building blocks of an application are:
- Activity: User interface component, which
corresponds to one screen at time.
- Intent Receiver: Wakes up a predefined action
through the external event.
- Service: A task, which is done in the background.
- Content Provider: A component, which allows sharing
some of the data with other processes and
applications.
Advantages of Android:
Open - Android allows access to core
mobile functionality through standard
API calls.
All applications are equal - Android does not differentiate between the phone's basic and third-party applications.
Fast and easy development - The SDK contains everything needed to build and run Android applications, including a true device emulator and advanced debugging tools.
Disadvantages of Android:
Security - Making source code available
to everyone in unsafe.
Incompetence - Google’s dependence on hardware and carrier partners puts the final product out of their control.
