22-05-2013, 03:13 PM
Android (operating system)
[attachment=54281]
INTRODUCTION
Android is a Linux-based operating system designed primarily for touchscreen mobile devices such as smartphones and tablet computers. Initially developed by Android, Inc., whom Google financially backed and later purchased in 2005,[9] Android was unveiled in 2007 along with the founding of the Open Handset Alliance: a consortium of hardware, software, and telecommunication companies devoted to advancing open standards for mobile devices.[10] The first Android-powered phone was sold in October 2008.[11]
Android is open source and Google releases the code under the Apache License.[12] This open source code and permissive licensing allows the software to be freely modified and distributed by device manufacturers, wireless carriers and enthusiast developers. Additionally, Android has a large community of developers writing applications ("apps") that extend the functionality of devices, written primarily in a customized version of the Javaprogramming language.[13] In October 2012, there were approximately 700,000 apps available for Android, and the estimated number of applications downloaded from Google Play, Android's primary app store, was 25 billion.[14][15]
These factors have allowed Android to become the world's most widely used smartphone platform[16] and the software of choice for technology companies who require a low-cost, customizable, lightweight operating system for high tech devices without developing one from scratch.[17] As a result, despite being primarily designed for phones and tablets, it has seen additional applications on televisions, games consoles and other electronics. Android's open nature has further encouraged a large community of developers and enthusiasts to use the open source code as a foundation for community-driven projects, which add new features for advanced users[18] or bring Android to devices which were officially released running other operating systems.
Android had a worldwide smartphone market share of 75% during the third quarter of 2012,[19] with 500 million devices activated in total and 1.3 million activations per day.[20][21] The operating system's success has made it a target for patent litigation as part of the so-called "smartphone wars" between technology companies.
History
Android, Inc. was founded in Palo Alto, California in October 2003 by Andy Rubin (co-founder of Danger),[22] Rich Miner (co-founder of Wildfire Communications, Inc.),[23] Nick Sears[24] (once VP at T-Mobile),[25] and Chris White (headed design and interface development at WebTV)[9] to develop, in Rubin's words "...smarter mobile devices that are more aware of its owner's location and preferences."[9] Despite the obvious past accomplishments of the founders and early employees, Android Inc. operated secretly, revealing only that it was working on software for mobile phones.[9] That same year, Rubin ran out of money. Steve Perlman, a close friend of Rubin, brought him $10,000 in cash in an envelope and refused a stake in the company.[26]
Google acquired Android Inc. on August 17, 2005, making it a wholly owned subsidiary of Google. Key employees of Android Inc., including Rubin, Miner and White, stayed at the company after the acquisition.[9] Not much was known about Android Inc. at the time, but many assumed that Google was planning to enter the mobile phone market with this move.[9] At Google, the team led by Rubin developed a mobile device platform powered by theLinux kernel. Google marketed the platform to handset makers and carriers on the promise of providing a flexible, upgradable system. Google had lined up a series of hardware component and software partners and signaled to carriers that it was open to various degrees of cooperation on their part.
Interface
Android's user interface is based on direct manipulation,[35] using touch inputs that loosely correspond to real-world actions, like swiping, tapping, pinching and reverse pinching to manipulate on-screen objects.[35] The response to user input is designed to be immediate and provides a fluid touch interface, often using the vibration capabilities of the device to provide haptic feedback to the user. Internal hardware such as accelerometers, gyroscopes and proximity sensors are used by some applications to respond to additional user actions, for example adjusting the screen from portrait to landscape depending on how the device is oriented, or allowing the user to steer a vehicle in a racing game by rotating the device, simulating control of a steering wheel.[36]
Development
Android is developed in private by Google until the latest changes and updates are ready to be released, at which point the source code is made available publicly.[49] This source code will only run without modification on select devices, usually the Nexus series of devices.[50] With many devices, there are proprietary components which have to be provided by the manufacturer, in order for Android to work.[51]
Memory management
Since Android devices are usually battery-powered, Android is designed to manage memory (RAM) to keep power consumption at a minimum, in contrast to desktop operating systems which generally assume they are connected to unlimited mains electricity. When an Android app is no longer in use, the system will automatically suspend it in memory - while the app is still technically "open," suspended apps consume no resources (e.g. battery power or processing power) and sit idly in the background until needed again. This has the dual benefit of increasing the general responsiveness of Android devices, since apps don't need to be closed and reopened from scratch each time, but also ensuring background apps don't waste power needlessly.[68]
Android manages the apps stored in memory automatically: when memory is low, the system will begin killing apps and processes that have been inactive for a while, in reverse order since they were last used (i.e. oldest first). This process is designed to be invisible to the user, such that users do not need to manage memory or the killing of apps themselves.[69] However, confusion over Android memory management has resulted in third-party task killers becoming popular on the Google Play store; these third-party task killers are generally regarded as doing more harm than good.[70]
Open source community
Android has an active community of developers and enthusiasts who use the Android source code to develop and distribute their own modified versions of the operating system.[78] These community-developed releases often bring new features and updates to devices faster than through the official manufacturer/carrier channels, albeit without as extensive testing or quality assurance;[18] provide continued support for older devices that no longer receive official updates; or bring Android to devices that were officially released running other operating systems, such as the HP Touchpad. Community releases often come pre-rooted and contain modifications unsuitable for non-technical users, such as the ability to overclock or over/undervolt the device's processor.[79] CyanogenMod is the most widely used community firmware,[80] and acts as a foundation for numerous others.
Licensing
The source code for Android is available under free and open source software licenses. Google publishes most of the code (including network and telephony stacks)[103] under the Apache Licenseversion 2.0,[104][105] and the rest, Linux kernel changes, under the GNU General Public License version 2. The Open Handset Alliance develops the changes to the Linux kernel, in public, with source code publicly available at all times. The rest of Android is developed in private by Google, with source code released publicly when a new version is released. Typically Google collaborates with a hardware manufacturer to produce a 'flagship' device (part of the Google Nexus series) featuring the new version of Android, then makes the source code available after that device has been released.[106]
In early 2011, Google chose to temporarily withhold the Android source code to the tablet-only 3.0 Honeycomb release. The reason, according to Andy Rubin in an official Android blog post, was because Honeycomb was rushed for production of the Motorola Xoom,[107] and they did not want third parties creating a "really bad user experience" by attempting to put onto smartphones a version of Android intended for tablets.[108] The source code was once again made available in November 2011 with the release of Android 4.0.[109]
[attachment=54281]
INTRODUCTION
Android is a Linux-based operating system designed primarily for touchscreen mobile devices such as smartphones and tablet computers. Initially developed by Android, Inc., whom Google financially backed and later purchased in 2005,[9] Android was unveiled in 2007 along with the founding of the Open Handset Alliance: a consortium of hardware, software, and telecommunication companies devoted to advancing open standards for mobile devices.[10] The first Android-powered phone was sold in October 2008.[11]
Android is open source and Google releases the code under the Apache License.[12] This open source code and permissive licensing allows the software to be freely modified and distributed by device manufacturers, wireless carriers and enthusiast developers. Additionally, Android has a large community of developers writing applications ("apps") that extend the functionality of devices, written primarily in a customized version of the Javaprogramming language.[13] In October 2012, there were approximately 700,000 apps available for Android, and the estimated number of applications downloaded from Google Play, Android's primary app store, was 25 billion.[14][15]
These factors have allowed Android to become the world's most widely used smartphone platform[16] and the software of choice for technology companies who require a low-cost, customizable, lightweight operating system for high tech devices without developing one from scratch.[17] As a result, despite being primarily designed for phones and tablets, it has seen additional applications on televisions, games consoles and other electronics. Android's open nature has further encouraged a large community of developers and enthusiasts to use the open source code as a foundation for community-driven projects, which add new features for advanced users[18] or bring Android to devices which were officially released running other operating systems.
Android had a worldwide smartphone market share of 75% during the third quarter of 2012,[19] with 500 million devices activated in total and 1.3 million activations per day.[20][21] The operating system's success has made it a target for patent litigation as part of the so-called "smartphone wars" between technology companies.
History
Android, Inc. was founded in Palo Alto, California in October 2003 by Andy Rubin (co-founder of Danger),[22] Rich Miner (co-founder of Wildfire Communications, Inc.),[23] Nick Sears[24] (once VP at T-Mobile),[25] and Chris White (headed design and interface development at WebTV)[9] to develop, in Rubin's words "...smarter mobile devices that are more aware of its owner's location and preferences."[9] Despite the obvious past accomplishments of the founders and early employees, Android Inc. operated secretly, revealing only that it was working on software for mobile phones.[9] That same year, Rubin ran out of money. Steve Perlman, a close friend of Rubin, brought him $10,000 in cash in an envelope and refused a stake in the company.[26]
Google acquired Android Inc. on August 17, 2005, making it a wholly owned subsidiary of Google. Key employees of Android Inc., including Rubin, Miner and White, stayed at the company after the acquisition.[9] Not much was known about Android Inc. at the time, but many assumed that Google was planning to enter the mobile phone market with this move.[9] At Google, the team led by Rubin developed a mobile device platform powered by theLinux kernel. Google marketed the platform to handset makers and carriers on the promise of providing a flexible, upgradable system. Google had lined up a series of hardware component and software partners and signaled to carriers that it was open to various degrees of cooperation on their part.
Interface
Android's user interface is based on direct manipulation,[35] using touch inputs that loosely correspond to real-world actions, like swiping, tapping, pinching and reverse pinching to manipulate on-screen objects.[35] The response to user input is designed to be immediate and provides a fluid touch interface, often using the vibration capabilities of the device to provide haptic feedback to the user. Internal hardware such as accelerometers, gyroscopes and proximity sensors are used by some applications to respond to additional user actions, for example adjusting the screen from portrait to landscape depending on how the device is oriented, or allowing the user to steer a vehicle in a racing game by rotating the device, simulating control of a steering wheel.[36]
Development
Android is developed in private by Google until the latest changes and updates are ready to be released, at which point the source code is made available publicly.[49] This source code will only run without modification on select devices, usually the Nexus series of devices.[50] With many devices, there are proprietary components which have to be provided by the manufacturer, in order for Android to work.[51]
Memory management
Since Android devices are usually battery-powered, Android is designed to manage memory (RAM) to keep power consumption at a minimum, in contrast to desktop operating systems which generally assume they are connected to unlimited mains electricity. When an Android app is no longer in use, the system will automatically suspend it in memory - while the app is still technically "open," suspended apps consume no resources (e.g. battery power or processing power) and sit idly in the background until needed again. This has the dual benefit of increasing the general responsiveness of Android devices, since apps don't need to be closed and reopened from scratch each time, but also ensuring background apps don't waste power needlessly.[68]
Android manages the apps stored in memory automatically: when memory is low, the system will begin killing apps and processes that have been inactive for a while, in reverse order since they were last used (i.e. oldest first). This process is designed to be invisible to the user, such that users do not need to manage memory or the killing of apps themselves.[69] However, confusion over Android memory management has resulted in third-party task killers becoming popular on the Google Play store; these third-party task killers are generally regarded as doing more harm than good.[70]
Open source community
Android has an active community of developers and enthusiasts who use the Android source code to develop and distribute their own modified versions of the operating system.[78] These community-developed releases often bring new features and updates to devices faster than through the official manufacturer/carrier channels, albeit without as extensive testing or quality assurance;[18] provide continued support for older devices that no longer receive official updates; or bring Android to devices that were officially released running other operating systems, such as the HP Touchpad. Community releases often come pre-rooted and contain modifications unsuitable for non-technical users, such as the ability to overclock or over/undervolt the device's processor.[79] CyanogenMod is the most widely used community firmware,[80] and acts as a foundation for numerous others.
Licensing
The source code for Android is available under free and open source software licenses. Google publishes most of the code (including network and telephony stacks)[103] under the Apache Licenseversion 2.0,[104][105] and the rest, Linux kernel changes, under the GNU General Public License version 2. The Open Handset Alliance develops the changes to the Linux kernel, in public, with source code publicly available at all times. The rest of Android is developed in private by Google, with source code released publicly when a new version is released. Typically Google collaborates with a hardware manufacturer to produce a 'flagship' device (part of the Google Nexus series) featuring the new version of Android, then makes the source code available after that device has been released.[106]
In early 2011, Google chose to temporarily withhold the Android source code to the tablet-only 3.0 Honeycomb release. The reason, according to Andy Rubin in an official Android blog post, was because Honeycomb was rushed for production of the Motorola Xoom,[107] and they did not want third parties creating a "really bad user experience" by attempting to put onto smartphones a version of Android intended for tablets.[108] The source code was once again made available in November 2011 with the release of Android 4.0.[109]