Android is an
operating system for mobile devices such as
smartphones and
tablet computers. It is developed by the
Open Handset Alliance led by
Google.
[7][8]
Google purchased the initial developer of the software, Android Inc., in 2005.
[9] The unveiling of the Android distribution on November 5, 2007 was announced with the founding of the
Open Handset Alliance, a consortium of 84
hardware, software, and
telecommunication companies devoted to advancing
open standards for mobile devices.
[10][11][12][13] Google released most of the Android code under the
Apache License, a
free software license.
[14] The Android Open Source Project (AOSP) is tasked with the maintenance and further development of Android.
[15]
Android consists of a
kernel based on the
Linux kernel, with
middleware,
libraries and
APIs written in
C and
application software running on an
application framework which includes Java-compatible libraries based on
Apache Harmony. Android uses the
Dalvik virtual machine with
just-in-time compilation to run Dalvik dex-code (Dalvik Executable), which is usually translated from
Java bytecode.
[16]
Android has a large community of developers writing applications
("apps") that extend the functionality of the devices. Developers write
primarily in a customized version of Java.
[17] There are currently approximately 400,000 apps available for Android, from a total of 600,000 apps over the life of Android.
[18][19][20] Apps can be downloaded from third-party sites or through online stores such as
Android Market, the app store run by Google.
Android was listed as the best-selling
smartphone platform worldwide in Q4 2010 by
Canalys[21][22] with over 200 million Android devices in use by November 2011.
[23]
[edit] History
[edit] Foundation
Android, Inc. was founded in
Palo Alto, California, United States in October, 2003 by
Andy Rubin (co-founder of
Danger),
[24] Rich Miner (co-founder of Wildfire Communications, Inc.),
[25] Nick Sears (once VP at
T-Mobile),
[26] and Chris White (headed design and interface development at
WebTV)
[27] to develop, in Rubin's words "...smarter mobile devices that are more aware of its owner's location and preferences".
[28]
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.
[28]
That same year, Rubin ran out of money.
Steve Perlman brought him $10,000 in cash in an envelope and refused a stake in the company.
[29]
[edit] Acquisition by Google
Google
acquired Android Inc. in August 2005, making Android Inc. a wholly
owned subsidiary of Google Inc. Key employees of Android Inc., including
Andy Rubin, Rich Miner and Chris White, stayed at the company after the
acquisition.
[9] Not much was known about Android Inc. at the time of the acquisition, but many assumed that Google was planning to enter the
mobile phone market with this move.
[9]
[edit] Post-acquisition development
At Google, the team led by Rubin developed a mobile device platform powered by the
Linux kernel. Google marketed the platform to handset makers and
carriers
on the premise 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.
[30][31][32]
Speculation about Google's intention to enter the mobile communications market continued to build through December 2006.
[33] Reports from the
BBC and
The Wall Street Journal
noted that Google wanted its search and applications on mobile phones
and it was working hard to deliver that. Print and online media outlets
soon reported rumors that Google was developing a Google-branded
handset.
[34]
Some speculated that as Google was defining technical specifications,
it was showing prototypes to cell phone manufacturers and network
operators.
In September 2007,
InformationWeek covered an
Evalueserve study reporting that Google had filed several
patent applications in the area of mobile telephony.
[35][36]
[edit] Open Handset Alliance
On November 5, 2007, the
Open Handset Alliance, a
consortium of several companies which include
Broadcom Corporation,
Google,
HTC,
Intel,
LG,
Marvell Technology Group,
Motorola,
Nvidia,
Qualcomm,
Samsung Electronics,
Sprint Nextel,
T-Mobile and
Texas Instruments unveiled itself. The goal of the Open Handset Alliance is to develop
open standards for mobile devices.
[12] On the same day, the Open Handset Alliance also unveiled their first product, Android, a mobile device
platform built on the
Linux kernel version 2.6.
[12]
On December 9, 2008, 14 new members joined, including
ARM Holdings,
Atheros Communications,
Asustek Computer Inc,
Garmin Ltd,
Huawei Technologies,
PacketVideo,
Softbank,
Sony Ericsson,
Toshiba Corp, and
Vodafone Group Plc.
[37][38]
[edit] Version history
Home screen of Android DarkyROM.
Android has seen a number of updates since its original release, each fixing
bugs and adding new features. Each version is named, in alphabetical order, after a dessert.
[39]
- Recent releases
- 2.3 Gingerbread refined the user interface, improved the soft keyboard and copy/paste features, improved gaming performance, added SIP support (VoIP calls), and added support for Near Field Communication.[40]
- 3.0 Honeycomb was a tablet-oriented[41][42][43] release which supports larger screen devices and introduces many new user interface features, and supports multi-core processors and hardware acceleration for graphics.[44] The first device featuring this version, the Motorola Xoom tablet, went on sale in February 2011.[45][46]
-
- 3.1 Honeycomb, released in May 2011, added support for extra
input devices, USB host mode for transferring information directly from
cameras and other devices, and the Google Movies and Books apps.[47]
-
- 3.2 Honeycomb, released in July 2011, added optimization for a
broader range of screen sizes, new "zoom-to-fill" screen compatibility
mode, loading media files directly from SD card, and an extended screen
support API.[48] Huawei MediaPad is the first 7 inch tablet to use this version [49]
- 4.0 Ice Cream Sandwich, announced on October 19, 2011,
brought Honeycomb features to smartphones and added new features
including facial recognition unlock, network data usage monitoring and
control, unified social networking contacts, photography enhancements,
offline email searching, and information sharing using NFC.
Android 4.0.1 Ice Cream Sandwich is the latest Android version that is
available to phones. The source code of Android 4.0.1 was released on
November 14, 2011[50]
[edit] Licensing
The
source code for Android is available under
free and open source software licenses. Google published their Linux kernel changes under the
GNU General Public License version 2, and the rest of the code (including network and telephony stacks)
[51] under the
Apache License version 2.0.
[52][53][54] Google also keeps the reviewed issues list publicly open for anyone to see and comment.
[55]
The Open Handset Alliance develops the GPL-licensed part of Android,
that is their changes to the Linux kernel, in public, with source code
publicly available at all times. The rest of Android is developed in
private, with source code released publicly when a major new version is
released. Typically Google collaborates with a hardware manufacturer to
produce a flagship device featuring the new version of Android, then
makes the source code available after that device has been released.
[56]
Even though the software is open source, device manufacturers cannot
use Google's Android trademark unless Google certifies that the device
complies with their Compatibility Definition Document (CDD). Devices
must also meet this definition to be eligible to license Google's
closed-source applications, including the
Android Market.
[57]
In September 2010,
Skyhook Wireless
filed a lawsuit against Google in which they alleged that Google had
used the compatibility document to block Skyhook's mobile positioning
service (XPS) from Motorola's Android mobile devices.
[58]
In December 2010 a judge denied Skyhook's motion for preliminary
injunction, saying that Google had not closed off the possibility of
accepting a revised version of Skyhook's XPS service, and that Motorola
had terminated their contract with Skyhook because Skyhook wanted to
disable Google's location data collection functions on Motorola's
devices, which would have violated Motorola's obligations to Google and
its carriers.
[59]
In early 2011, Google chose to temporarily withhold the Android
source code to the tablet-only Honeycomb release, creating doubts over
Google's commitment to open source with Android.
[60] The reason, according to
Andy Rubin in an official Android blog post, was because Honeycomb was rushed for production of the Motorola Xoom,
[61]
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.
[62] The source code was made available again in November 2011 with the release of Android 4.0.
[3]
[edit] Design
Android's kernel is a
fork of the
Linux kernel and has further architecture changes by Google outside the typical Linux kernel development cycle.
[63] Android does not have a native
X Window System nor does it support the full set of standard
GNU libraries, and this makes it difficult to port existing Linux applications or libraries to Android.
[64]
Certain features that Google contributed back to the kernel, notably a
power management feature called wakelocks, were rejected by mainline
kernel developers, partly because kernel maintainers felt that Google
did not show any intent to maintain their own code.
[65][66][67] Even though Google announced in April 2010 that they would hire two employees to work with the Linux kernel community,
[68] Greg Kroah-Hartman,
the current Linux kernel maintainer for the -stable branch, said in
December 2010 that he was concerned that Google was no longer trying to
get their code changes included in mainstream Linux.
[66]
Some Google Android developers hinted that "the Android team was
getting fed up with the process", because they were a small team and had
more urgent work to do on Android.
[69]
However, in September 2010 Linux kernel developer Rafael J. Wysocki
added a patch that improved the mainline Linux wakeup events framework.
He said that Android device drivers that use wakelocks can now be easily
merged into mainline Linux, but that Android's opportunistic suspend
features should not be included in the mainline kernel.
[70][71] In 2011
Linus Torvalds
said that "eventually Android and Linux would come back to a common
kernel, but it will probably not be for four to five years."
[72]
[edit] Features
The Android Emulator default home screen (v1.5)
Current features and specifications:
[73][74][75]
- Handset layouts
- The platform is adaptable to larger, VGA, 2D graphics library, 3D graphics library based on OpenGL ES 2.0 specifications, and traditional smartphone layouts.
- Storage
- SQLite, a lightweight relational database, is used for data storage purposes.
- Connectivity
- Android supports connectivity technologies including GSM/EDGE, IDEN, CDMA, EV-DO, UMTS, Bluetooth, Wi-Fi, LTE, NFC and WiMAX.
- Messaging
- SMS and MMS are available forms of messaging, including threaded text messaging and now Android Cloud To Device Messaging (C2DM) is also a part of Android Push Messaging service.
- Multiple language support
- Android supports multiple languages.[40]
- Web browser
- The web browser available in Android is based on the open-source WebKit layout engine, coupled with Chrome's V8 JavaScript engine. The browser scores 100/100 on the Acid3 test on Android 4.0, however does have some rendering issues.
- Java support
- While most Android applications are written in Java, there is no Java Virtual Machine in the platform and Java byte code is not executed. Java classes are compiled into Dalvik executables and run on Dalvik,
a specialized virtual machine designed specifically for Android and
optimized for battery-powered mobile devices with limited memory and
CPU. J2ME support can be provided via third-party applications.
- Media support
- Android supports the following audio/video/still media formats: WebM, H.263, H.264 (in 3GP or MP4 container), MPEG-4 SP, AMR, AMR-WB (in 3GP container), AAC, HE-AAC (in MP4 or 3GP container), MP3, MIDI, Ogg Vorbis, FLAC, WAV, JPEG, PNG, GIF, BMP.[75]
- Streaming media support
- RTP/RTSP streaming (3GPP PSS, ISMA),
HTML progressive download (HTML5 <video> tag). Adobe Flash
Streaming (RTMP) and HTTP Dynamic Streaming are supported by the Flash
plugin.[76] Apple HTTP Live Streaming is supported by RealPlayer for Mobile,[77] and by the operating system in Android 3.0 (Honeycomb).[44]
- Additional hardware support
- Android can use video/still cameras, touchscreens, GPS, accelerometers, gyroscopes, barometers, magnetometers, dedicated gaming controls, proximity and pressure sensors, thermometers, accelerated 2D bit blits (with hardware orientation, scaling, pixel format conversion) and accelerated 3D graphics.
- Multi-touch
- Android has native support for multi-touch which was initially made available in handsets such as the HTC Hero.
The feature was originally disabled at the kernel level (possibly to
avoid infringing Apple's patents on touch-screen technology at the
time).[78] Google has since released an update for the Nexus One and the Motorola Droid which enables multi-touch natively.[79]
- Bluetooth
- Supports A2DP, AVRCP, sending files (OPP), accessing the phone book (PBAP), voice dialing and sending contacts between phones. Keyboard, mouse and joystick (HID)
support is available in Android 3.1+, and in earlier versions through
manufacturer customizations and third-party applications.[80]
- Video calling
- Android does not support native video calling, but some handsets
have a customized version of the operating system that supports it,
either via the UMTS network (like the Samsung Galaxy S) or over IP. Video calling through Google Talk is available in Android 2.3.4 and later. Gingerbread allows Nexus S
to place Internet calls with a SIP account. This allows for enhanced
VoIP dialing to other SIP accounts and even phone numbers. Skype 2.1
offers video calling in Android 2.3, including front camera support.
- Multitasking
- Multitasking of applications is available.[81]
- Voice based features
- Google search through voice has been available since initial release.[82] Voice actions for calling, texting, navigation, etc. are supported on Android 2.2 onwards.[83]
- Tethering
- Android supports tethering, which allows a phone to be used as a wireless/wired Wi-Fi hotspot. Before Android 2.2 this was supported by third-party applications or manufacturer customizations.[84]
- Screen capture
- Android has native support for screenshot
capture ability by pressing the power and volume buttons at the same
time on an Android device. This native support came about with the
release of Android's 4.0 (Ice Cream Sandwich) update which is first seen on the Galaxy Nexus smartphone.[85]
Previously Android did not feature native support for screen capturing
which would have likely been due to security concerns. Furthermore
previously, manufacturer and third-party customizations as well as using
a PC connection (DDMS developer's tool) were the only known methods of
capturing a screenshot on Android.[86]
The open and customizable nature of the Android operating system
allows it to be used in pretty much any electronics, including but not
limited to:
smartphones,
laptops,
netbooks,
tablet computers,
Google TV,
wristwatches,
[87] headphones,
[88] Car CD and DVD players
[89] and other devices.
[90][91][92]
The main hardware platform for Android is the
ARM architecture. There is support for
x86 from the Android-x86 project,
[93] and Google TV uses a special x86 version of Android.
The first commercially available phone to run Android was the
HTC Dream, released on 22 October 2008.
[94] In early 2010 Google collaborated with
HTC to launch its flagship
[95] Android device, the
Nexus One. This was followed later in 2010 with the
Samsung-made
Nexus S and in 2011 with the
Galaxy Nexus.
iOS and Android 2.3.3 'Gingerbread' may be set up to dual boot on a
jailbroken iPhone or iPod Touch with the help of OpeniBoot and iDroid.
[96][97]
[edit] Applications
Applications are usually developed in the Java language using the
Android Software Development Kit, but other development tools are available, including a
Native Development Kit for applications or extensions in C or C++,
Google App Inventor, a visual environment for novice programmers and various
cross platform mobile web applications frameworks .
[edit] Android Market
Main article:
Android Market
Android Market is the online software store developed by Google for
Android devices. An application program ("app") called "Market" is
preinstalled on most Android devices and allows users to browse and
download apps published by third-party developers, hosted on Android
Market. As of December 2010
[update] there were about 200,000 games, applications and widgets available on the Android Market.
[98] In April 2011 Google said there had been more than 3 billion Android apps installed
[99]
and at end of June 2011 there are 6 billion apps installs from the
Android market. The operating system itself is installed on 130 million
total devices.
[100]
Only devices that comply with Google's compatibility requirements are
allowed to preinstall Google's closed-source Android Market app and
access the Market.
[101]
The Market filters the list of applications presented by the Market app
to those that are compatible with the user's device, and developers may
restrict their applications to particular carriers or countries for
business reasons.
[102]
Google has participated in the Android Market by offering several applications themselves, including
Google Voice
(for the Google Voice service), Sky Map (for watching stars), Finance
(for their finance service), Maps Editor (for their MyMaps service),
Places Directory (for their Local Search),
Google Goggles
that searches by image, Gesture Search (for using finger-written
letters and numbers to search the contents of the phone), Google
Translate, Google Shopper, Listen for podcasts and My Tracks, a jogging
application. In August 2010, Google launched "Voice Actions for
Android",
[103] which allows users to search, write messages, and initiate calls by voice.
Alternatively, users can install apps from third party app stores such as the
Amazon Appstore,
[104] or directly onto the device if they have the application's
APK file.
[edit] Application security
An example of app permissions in Android Market.
Android applications run in a
sandbox,
an isolated area of the operating system that does not have access to
the rest of the system's resources, unless access permissions are
granted by the user when the application is installed. Before installing
an application, Android Market displays all required permissions. A
game may need to enable vibration, for example, but should not need to
read messages or access the phonebook. After reviewing these
permissions, the user can decide whether to install the application.
[105]
Some Android
malware incidents have been reported involving rogue applications on Android Market. In August 2010,
Kaspersky Lab reported detection of the first malicious program for Android, named
Trojan-SMS.AndroidOS.FakePlayer.a, an
SMS trojan which had already infected a number of devices.
[106] In some cases applications which contained
Trojans were hidden in
pirated versions of legitimate apps.
[107][108] Google has responded by removing malicious apps from the Android Market, and remotely disabling them on infected devices.
[109] Security firms such as
AVG Technologies and
Symantec have released antivirus software for Android devices.
[edit] Privacy
Android smartphones have the ability to report the location of
Wi-Fi
access points, encountered as phone users move around, to build vast
databases containing the physical locations of hundreds of millions of
such access points. These databases form electronic maps to locate
smartphones, allowing them to run apps like
Foursquare,
Latitude,
Places, and to deliver location-based ads.
[110]
One design issue is that average users cannot monitor how
applications access and use private and sensitive data (e.g. location
and hardware ID numbers). Even during installation, permission checks do
not often indicate to the user how critical services and data will be
used or misused. Third party monitoring software such as TaintDroid,
[111] an academic research-funded project, can identify personal information sent from applications to remote servers.
[112]
[edit] Marketing
The Android logo was designed along with the
Droid font family made by
Ascender Corporation.
[113]
Android Green is the color of the Android Robot that represents the Android operating system. The print color is
PMS 376C and the
RGB color value in hexadecimal is #A4C639, as specified by the Android Brand Guidelines.
[114] The custom typeface of Android is called Norad (cf.
NORAD). It is only used in the text logo.
[115]
[edit] Market share
Research company
Canalys estimated in Q2 2009 that Android had a 2.8% share of worldwide
smartphone shipments.
[116]
By Q4 2010 this had grown to 33% of the market, becoming the
top-selling smartphone platform. This estimate includes the Tapas and
OMS variants of Android.
[21] By Q3 2011
Gartner estimates more than half (52.5%) of the smartphone market belongs to Android.
[117]
In February 2010
ComScore
said the Android platform had 9.0% of the U.S. smartphone market, as
measured by current mobile subscribers. This figure was up from an
earlier estimate of 5.2% in November 2009.
[118] By the end of Q3 2010 Android's U.S. market share had grown to 21.4%.
[119]
In May 2010, Android's first quarter U.S. sales surpassed that of the
rival iPhone platform. According to a report by the NPD group, Android
achieved 25% smartphone sales in the US market, up 8% from the December
quarter. In the second quarter, Apple's iOS was up by 11%, indicating
that Android is taking market share mainly from
RIM, and still has to compete with heavy consumer demand for new competitor offerings.
[120]
Furthermore, analysts pointed to advantages that Android has as a
multi-channel, multi-carrier OS, which allowed it to duplicate the quick
success of Microsoft's Windows Mobile.
[121] In Q4 2010 Android had 59% of the total installed user base of Apple's
iOS in the U.S. and 46% of the total installed user base of
iOS in Europe.
[122][123]
As of June 2011
[update], Google said that 550,000 new Android devices were being activated every day
[124]— up from 400,000 per day a month earlier — and more than 100 million devices had been activated.
[19]
Android hit 300,000 activations per day back in December 2010. By the
14th of July 2011, 550,000 Android devices were being activated by
Google each day, with 4.4% growth per week.
[125] On the 1st of August 2011,
Canalys estimated that Android had about 48% of the smartphone market share.
[126] On October 13, 2011, Google announced that there were 190 million Android devices in the market.
[127]
As of November 16, 2011, during the Google Music announcement "These Go
to Eleven", 200 million Android devices had been activated.
[128]
Based on this number, with 1.9% of Android devices being tablets,
approximately 3.8 million Android Honeycomb Tablets have been sold.
[129]
[edit] Usage share
Usage share of the different versions, by December 1, 2011.
[130]
- Version
4.0 Ice Cream Sandwich |
14-15 |
0% |
3.x.x Honeycomb |
11-13 |
2.4% |
2.3.x Gingerbread |
9-10 |
50.6% |
2.2 Froyo |
8 |
35.3% |
2.1 Eclair |
7 |
9.6% |
1.6 Donut |
4 |
1.3% |
1.5 Cupcake |
3 |
0.8% |
[edit] Retail Stores
The world's first Android store opened on Bourke Street, Melbourne in December 2011.
[131]
[edit] Intellectual property infringement claims
Both Android and Android phone manufacturers have been the target of numerous patent lawsuits. On 12 August 2010,
Oracle sued Google over claimed infringement of copyrights and patents related to the
Java programming language.
[132] Specifically, the patent infringement claim references seven United States patents including
US 5966702 "Method and apparatus for pre-processing and packaging class files", and
US 6910205 "Interpreting functions utilizing a hybrid of virtual and native machine instructions".
[133].
In response, Google submitted multiple lines of defense,
counterclaiming that Android did not infringe on Oracle's patents or
copyright, that Oracle's patents were invalid, and several other
defenses. They said that Android is based on
Apache Harmony, a
clean room implementation of the Java class libraries, and an independently developed virtual machine called
Dalvik.
[134][135][136]
Microsoft
has also sued several manufacturers of Android devices for patent
infringement, and collects patent licensing fees from others. In October
2011 Microsoft said they had signed license agreements with ten Android
device manufacturers, accounting for 55% of worldwide revenue for
Android devices.
[137] These include
Samsung and
HTC.
[138]
Apple Inc. CEO
Steve Jobs claimed that Android copied major elements of Apple's
iPhone and
iOS operating system. According to his
biography,
Jobs stated that Android is a "stolen product," and vowed to destroy
it. “I will spend my last dying breath if I need to, and I will spend
every penny of Apple's $40 billion in the bank, to right this wrong,”
said Jobs.
[139]
Google has publicly expressed its dislike for the current patent landscape in the
United States,
accusing Apple, Oracle and Microsoft of trying to take down Android
through patent litigation, rather than innovating and competing with
better products and services.
[140] In August 2011, Google purchased
Motorola Mobility for
US$12.5
billion, which was viewed in part as a defensive measure to protect
Android, since Motorola Mobility has a 17,000-strong patent pool.
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