What is android ?
The term Android is commonly
used to refer to the operating system, and
that's accurate but incomplete. Android is a complete software
platform that includes the operation system which is
based on Linux, but is specifically designed to
be run on mobile devices such as cell phones and
tablets. But in addition to the operating system, the
Android platform includes a complete application framework that lets you create
and deploy your own custom apps.
Android was founded in Palo Alto, California in October 2003 by Andy Rubin, Rich Miner, Nick Sears and Chris White. Initially this technology was developed for the Mobile devices. Android is used in numerous smartphones, e-reader devices and tablet computers.
Android is an operating system based on the Linux kernel. The project responsible for developing the Android system is called theAndroid Open Source Project (AOSP) and is primarily lead by Google.
The Android system supports background processing, provides a rich user interface library, supports 2-D and 3-D graphics using the OpenGL-ES (short OpenGL) standard and grants access to the file system as well as an embedded SQLite database.
An Android application typically consists of different visual and non visual components and can reuse components of other applications.
What is open Handset Alliance(OHA)?
In November 2007 , the Open Source Alliance a 34-Company consortium initially and now its 81 was for to develop Android ,Innovation in mobile technology , improving the user experience.
Open Handset Alliance basically a consortium of Mobile Operators , Handset Manufacturers , Software Companies , Semi-Conductor companies and Commercialization Companies.
Initially the AIM of the OHA was to develop an Hardware which support the android technology. In October 2008 first generation of Android phones are released. First android supported hardware was provided by the HTC-Dream.
Key Points of Android :
1. Open Source Technology
Android is an open source technology which means it is free of cost and original copy of android is available.Android is an open-source software stack created for a wide array of devices with different form factors. The primary purposes of Android are to create an open software platform available for carriers, OEMs, and developers to make their innovative ideas a reality and to introduce a successful, real-world product that improves the mobile experience for users.
2.Android is an Software stack
Android is an software stack for mobile devices i.e. its include Key Application , Middle-ware and Os.
3.Google
Android is acquired by Google in July 2005.
Google offers a variety of services that help you build new revenue streams, manage app distribution, track app usage, and enhance your app with features such as maps, sign-in, and cloud messaging.
Although these Google services are not included in the Android platform, they are supported by most Android-powered devices. When using these services, you can distribute your app on Google Play to all devices running Android 2.3 or higher, and some services support even more devices.
4. Core Java API's
Core java is used to create the android based applications.The Core-Java APIs Library is a flexible, efficient, and powerful Java client library for accessing any HTTP-based API on the web.
The library has the following features:
- A powerful OAuth 2.0 library with a consistent interface.
- Lightweight, efficient XML and JSON data models that support any data schema.
- Support for protocol buffers.
- A set of generated libraries for Google APIs.
5.AVD
Android Virtual Device provides QEMU base Emulator technology which provides ease for developers to test , debug and develop the android application.
An Android Virtual Device (AVD) is an emulator configuration that lets you model an actual device by defining hardware and software options to be emulated by the Android Emulator.
An AVD consists of:
- A hardware profile: Defines the hardware features of the virtual device. For example, you can define whether the device has a camera, whether it uses a physical QWERTY keyboard or a dialing pad, how much memory it has, and so on.
- A mapping to a system image: You can define what version of the Android platform will run on the virtual device. You can choose a version of the standard Android platform or the system image packaged with an SDK add-on.
- Other options: You can specify the emulator skin you want to use with the AVD, which lets you control the screen dimensions, appearance, and so on. You can also specify the emulated SD card to use with the AVD.
- A dedicated storage area on your development machine: the device's user data (installed applications, settings, and so on) and emulated SD card are stored in this area.
6.DVM
Dalvik is the process virtual machine (VM) in Google's Android operating system, which, specifically, executes applications written for Android.
7.Linux Kernel 2.6
"Linux is open source" that means, one can make enhancements upon the Linux kernel structure( maintaining the GNU licence agreement). Hence, Android takes Linux 2.6 as its underlying kernel and makes enhancements to meet mobile O/S requirements such as better memory management, better processor management.
Android devices mainly use versions 3.4 or 3.10 of the Linux kernel.The specific kernel version depends on the actual Android device and its hardware platform;Android has used various kernel versions since the version 2.6.25 that was used in Android 1.0.
Android's variant of the Linux kernel has further architectural changes that are implemented by Google outside the typical Linux kernel development cycle, such as the inclusion of components like Binder , ashmem, pmem, logger, wakelocks, and different out of memory (OOM) handling.
Platform code names and versions
The code names match the following version numbers, along with API levels and NDK releases provided for convenience:
| Code name | Version | API level |
|---|---|---|
| Lollipop | 5.0 | API level 21 |
| KitKat | 4.4 - 4.4.4 | API level 19 |
| Jelly Bean | 4.3.x | API level 18 |
| Jelly Bean | 4.2.x | API level 17 |
| Jelly Bean | 4.1.x | API level 16 |
| Ice Cream Sandwich | 4.0.3 - 4.0.4 | API level 15, NDK 8 |
| Ice Cream Sandwich | 4.0.1 - 4.0.2 | API level 14, NDK 7 |
| Honeycomb | 3.2.x | API level 13 |
| Honeycomb | 3.1 | API level 12, NDK 6 |
| Honeycomb | 3.0 | API level 11 |
| Gingerbread | 2.3.3 - 2.3.7 | API level 10 |
| Gingerbread | 2.3 - 2.3.2 | API level 9, NDK 5 |
| Froyo | 2.2.x | API level 8, NDK 4 |
| Eclair | 2.1 | API level 7, NDK 3 |
| Eclair | 2.0.1 | API level 6 |
| Eclair | 2.0 | API level 5 |
| Donut | 1.6 | API level 4, NDK 2 |
| Cupcake | 1.5 | API level 3, NDK 1 |
| (no code name) | 1.1 | API level 2 |
| (no code name) | 1.0 | API level 1 |
The first version of Android
was released in late 2008. Version one included a web browser, support for cameras on phones, and many Google services including search, Google maps, synchronization of Gmail, contacts and other services, instant messaging, a media player and more. Version 1.1 was released just a
few months later in February of 2009, and it included
improvements to Google Maps, showing and hiding the dial pad, saving attachments from emails, and other new
features.
The next version of Android
was 1.5 and it was the first one that had a code name for a delicious dessert, this was Cupcake in April 2009. And it improved support for videos, added a home screen
architecture, application widgets, copy and pasted the web
browser and many other new features. The next version was 1.6 or
Donut, in September of 2009, it expanded the number of
gestures available for multi touch devices, and added
an integrated image gallery.
Eclair came along in October of
2009, that was version 2.0, and it added
support for multiple Google accounts, upgraded to Bluetooth
2.1, added support for Microsoft Exchange, search of SMS
messages, and supported more screen sizes. To better
support the variety of devices that were coming on to the market. The next version was 2.2 or Froyo, and as you'll see in a moment, this is the most recent version of Android that is still actively
used in the wild.
That is on devices that's
actually in people's hands. It was released in May of 2009, and it significantly speeded up
the operating system, and improved memory management. In
Chrome, the new JavaScript engine named V8 was added. And features were added including USB tethering and Wi-Fi
hotspots. Version 2.3, or Gingerbread, came along in
December of 2010, and this is the dominant version of the
operating system that's still used on low memory, low
power devices.
Gingerbread added a concurrent
garbage collector, video and audio improvements, NFC or near field communication, and enhancements to the clipboard. Around this time, Android tablets started appearing, and so the
next version of Android, Honeycomb version 3.0
came along in February of 2011. It was specifically optimized
for tablets, and included the new fragments API,
the action bar, which is very important to
modern Android apps, and much, much more.
But the Honeycomb operating
system really only worked on tablets, and for a
short time,developers had to build for two distinct operating systems, Gingerbread for phones, and Honeycomb for tablets. And that was the case until Ice Cream Sandwich came along, in
October of 2011. Ice Cream Sandwich, or version 4.0, unified the SDKs for tablets and smartphones, and added improved audio support and a customizable launcher
environment.
Moving along, we come to Jelly
Bean, and there are three variants of Jelly Bean, version 4.1 improved performance, and it was known as" Project Butter", as in, smooth like butter. Version 4.2, released in November 2012,
improved the camera support, added multi-user support on tablets, and added a unified interface layout engine,
and 4.3 which came along in the summer of 2013, still named Jelly Bean, added Bluetooth low energy, improved gaming graphics, and
more.
The most recent version of
Android is 4.4 or KitKat, and it was released in
October 2013.Version 4.4 add significant new tools for memory and power management, with the ultimate goal of having a single operating system for both powerful tablets, and modern phones and less costly low powered and low memory devices. Version 4.4 also has improvements for NFC, a new printing framework, a new framework and API for managing
storage, a new way of designating an application
as default SMS receiver, rich media functionality,
accessibility, and much much more.
Regardless of which version of
Android you're working on, it's important to
know the history of the operating system and of the
platform of which it's a part of.
Android "Lollipop", or simply "Android L", is the latest version of the Android mobile operating system developed by Google, spanning versions between 5.0 and 5.1. Unveiled on June 25, 2014 during Google I/O, it became available through official over-the-air (OTA) updates on November 12, 2014, for select devices that run distributions of Android serviced by Google (such as Nexus andGoogle Play edition devices). Its source code was made available on November 3, 2014.
One of the most prominent changes in the Lollipop release is a redesigned user interface built around a design language referred to as "material design". Other changes include improvements to the notifications, which can be accessed from the lockscreen and displayed within applications as top-of-the-screen banners. Google also made internal changes to the platform, with the Android Runtime (ART) officially replacing Dalvik for improved application performance, and with changes intended to improve and optimize battery usage, known internally as Project Volta.
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