Introduction:Android is a Linux-based mobile phone operatingsystem developed by Google. Android is uniquebecause Google is actively developing theplatform but giving it away for free to hardwaremanufacturers and phone carriers who want to useAndroid on their devices.Beyond the Phone:A modified version of Android is used in the GoogleTV, the Barnes & Noble Nook e-Reader, theSamsung Galaxy Tab, and countless other devices.Parrot makes both a digital photo frame and a carstereo system powered by modified versions ofAndroid.
What is android?Android is a Linux-based operating system for mobile devices such as smartphones and tablet computers, developed by Google in conjunction with theOpen Handset Alliance. Android was initially developed by Android Inc, whomGoogle financially backed and later purchased in 2005. The unveiling of theAndroid distribution in 2007 was announced with the founding of the OpenHandset Alliance, a consortium of 86 hardware, software, andtelecommunication companies devoted to advancing open standards formobile devices. Google releases the Android code as open-source, under theApache License. The Android Open Source Project (AOSP) is tasked with themaintenance and further development of Android.Android has a large community of developers writing applications ("apps") thatextend the functionality of the devices. Developers write primarily in acustomized version of Java, and apps can be downloaded from online storessuch as Google Play (formerly Android Market), the app store run by Google, orthird-party sites. In June 2012, there were more than 600,000 apps available forAndroid, and the estimated number of applications downloaded from GooglePlay was 20 billion.Android became the world’s leading Smartphone platform at the end of 2010.For the first quarter of 2012, Android had a 59% Smartphone market shareworldwide. At the half of 2012, there were 400 million devices activated and 1million activations per day.
Foundation:Android, Inc. was founded in Palo Alto, California,United States in October 2003 by Andy Rubin (co-founder of Danger),Rich Miner (co-founder of WildfireCommunications, Inc.),Nick Sears (once VP at T-Mobile),and Chris White (headed design and interfacedevelopment at WebTV) to develop, in Rubins words"...smarter mobile devices that are more aware of itsowners location and preferences". Despite the obviouspast accomplishments of the founders and earlyemployees, Android Inc. operated secretly, revealingonly that it was working on software for mobile phones.That same year, Rubin ran out of money. Steve Perlman,a close friend of Rubin, brought him $10,000 in cash inan envelope and refused a stake in the company.
Google acquisition:Google acquired Android Inc. on August 17, 2005, making Android Inc. a whollyowned subsidiary of Google. Key employees of Android Inc., including AndyRubin, Rich Miner and Chris White, stayed at the company after the acquisition.Not much was known about Android Inc. at the time of the acquisition, but manyassumed that Google was planning to enter the mobile phone market with thismove.At Google, the team led by Rubin developed a mobile device platformpowered by the Linux kernel. Google marketed the platform to handset makersand carriers on the promise of providing a flexible, upgradable system. Googlehad lined up a series of hardware component and software partners andsignaled to carriers that it was open to various degrees of cooperation on theirpart.Speculation about Googles intention to enter the mobile communicationsmarket continued to build through December 2006. Reports from the BBC andThe Wall Street Journal noted that Google wanted its search and applications onmobile phones and it was working hard to deliver that. Print and online mediaoutlets soon reported rumors that Google was developing a Google-brandedhandset. 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 reportingthat Google had filed several patent applications in the area of mobiletelephony.
Open Handset Alliance:Main article: Open Handset AllianceOn November 5, 2007, the Open Handset Alliance, aconsortium of several companies which include BroadcomCorporation, Google, HTC, Intel, LG, Marvell TechnologyGroup, Motorola, Nvidia, Qualcomm, SamsungElectronics, Sprint Nextel, T-Mobile and Texas Instrumentsunveiled itself. The goal of the Open Handset Alliance is todevelop open standards for mobile devices. On the sameday, the Open Handset Alliance also unveiled its firstproduct, Android, a mobile device platform built on the Linuxkernel version 2.6.On December 9, 2008, 14 new members joined, including ARMHoldings, Atheros Communications, Asustek ComputerInc, Garmin Ltd, HuaweiTechnologies, PacketVideo, Softbank, Sony Ericsson, Toshiba
Android Open SourceProject:The Android Open Source Project (AOSP) is led byGoogle, and is tasked with the maintenance anddevelopment of Android. According to the project "Thegoal of the Android Open Source Project is to create asuccessful real-world product that improves the mobileexperience for end users.”AOSP also maintains theAndroid Compatibility Program, defining an "Androidcompatible" device "as one that can run any applicationwritten by third-party developers using the Android SDKand NDK", to prevent incompatible Androidimplementations. The compatibility program is alsooptional and free of charge, with the Compatibility TestSuite also free and open-source
Version history:Main article: Android version historyFrom left to right: HTC Dream (G1), Nexus One, Nexus S, Galaxy NexusEach version after "Astro" and "Bender" is named in alphabetical orderafter a dessert or sugary treat, with 1.5 "Cupcake" being the first and everyupdate since following this naming convention.
Design:Android consists of a kernel based on the Linuxkernel 2.6 and Linux Kernel 3.x (Android 4.0onwards), with middleware, libraries and APIswritten in C and application software running onan 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 (DalvikExecutable), which is usually translated from Javabyte code.The main hardware platform for Android is theARM architecture. There is support for x86 from theAndroid x86 project, and Google TV uses a specialx86 version of Android.
Linux:Androids kernel is based on the Linux kernel and has further architecture changes byGoogle outside the typical Linux kernel development cycle. Android does not have anative X Window System by default 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.Certain features that Google contributed back to the Linux kernel, notably a powermanagement feature called wakelocks, were rejected by mainline kernel developers,partly because kernel maintainers felt that Google did not show any intent to maintain theirown code. Even though Google announced in April 2010 that they would hire twoemployees to work with the Linux kernel community, Greg Kroah-Hartman, the current Linuxkernel maintainer for the -stable branch, said in December 2010 that he was concernedthat Google was no longer trying to get their code changes included in mainstream Linux.Some Google Android developers hinted that "the Android team was getting fed up withthe process", because they were a small team and had more urgent work to do onAndroid.However, in September 2010, Linux kernel developer Rafael J. Wysocki added a patch thatimproved the mainline Linux wakeup events framework. He said that Android device driversthat use wakelocks can now be easily merged into mainline Linux, but that Androidsopportunistic suspend features should not be included in the mainline kernel.In August 2011,Linus Torvalds said that "eventually Android and Linux would come back to a commonkernel, but it will probably not be for four to five years”.In December 2011, Greg Kroah-Hartman announced the start of the Android MainliningProject, which aims to put some Android drivers, patches and features back into the Linuxkernel, starting in Linux 3.3.further integration being expected for Linux Kernel 3.4.
•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, WebP.•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. Apple HTTP Live Streaming is supported by RealPlayer for Android, and by the operating system in Android 3.0 (Honeycomb).•Additional hardware support Android can use video/still cameras, touch screens, 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 Apples patents on touch-screen technology at the time). Google has since released an update for the Nexus One and the Motorola Droid which enables multi-touch natively. 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.
•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, with unique handling of memory allocation, is available.•Voice based features Google search through voice has been available since initial release. Voice actions for calling, texting, navigation, etc. are supported on Android 2.2 onwards.•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.•Screen capture Android supports capturing a screenshot by pressing the power and volume-down buttons at the same time. Prior to Android 4.0, the only methods of capturing a screenshot were through manufacturer and third-party customizations or otherwise by using a PC connection (DDMS developers tool). These alternative methods are still available with the latest Android.•External storage Most Android devices include micro SD slot and can read micro SD cards formatted with FAT32, Ext3 or Ext4 file system. To allow use of high-capacity storage media such as USB flash drives and USB HDDs, many Android tablets also include USB A receptacle. Storage formatted with FAT32 is handled by Linux Kernel VFAT driver, while 3rd party solutions are required to handle other popular file systems such as NTFS, HFS Plus and exFAT.
Uses:While Android is designed primarily for smartphones and tablets, theopen and customizable nature of the operating system allows it to beused on other electronics, including laptops and netbooks, smartbooks, e-book readers, and smart TVs (Google TV). Further, the OS hasseen niche applications on wristwatches, headphones, car CD andDVD players, smart glasses (Project Glass), refrigerators, vehiclesatnav systems, home automation systems, games consoles, mirrors,cameras, portable media players, landlines, and treadmills.The first commercially available phone to run Android was the HTCDream, released on October 22, 2008. In early 2010 Googlecollaborated with HTC to launch its flagship Android device, theNexus One. This was followed later in 2010 with the Samsung-madeNexus S and in 2011 with the Galaxy Nexus.iOS and Android 2.3.3 Gingerbread may be set up to dual boot on ajail broken iPhone or iPod Touch with the help of OpeniBoot andiDroid.In December 2011 it was announced the Pentagon has officiallyapproved Android for use by its personnel.
Applications:Applications are usually developed in the Javalanguage using the Android SoftwareDevelopment Kit, but other development toolsare available, including a Native DevelopmentKit for applications or extensions in C orC++, Google App Inventor, a visual environmentfor novice programmers and various crossplatform mobile web applications frameworks.Applications can be acquired by end-users eitherthrough a store such as Google Play or theAmazon Appstore, or by downloading andinstalling the applications APK file from a third-party site.
GOOGLE PLAY:Google Play is an online software store developed by Google forAndroid devices. An application program ("app") called "PlayStore" is preinstalled on most Android devices and allows users tobrowse and download apps published by third-partydevelopers, hosted on Google Play. As of June 2012, there weremore than 600,000 apps available for Android, and the estimatednumber of applications downloaded from the Play Storeexceeded 20 billion. The operating system itself is installed on 400million total devices.Only devices that comply with Googles compatibility requirementsare allowed to preinstall and access the Play Store. The app filtersthe list of available applications to those that are compatible withthe users device, and developers may restrict their applications toparticular carriers or countries for business reasons.Google offers many free applications in the Play Store includingGoogle Voice, Google Goggles, Gesture Search, GoogleTranslate, Google Shopper, Listen and My Tracks. In August2010, Google launched "Voice Actions for Android", which allowsusers to search, write messages, and initiate calls by voice.
Licensing:The source code for Android is available under free and open sourcesoftware licenses. Google publishes most of the code (including networkand telephony stacks) under the Apache License version 2.0, and therest, Linux kernel changes, under the GNU General Public License version2.The Open Handset Alliance develops the changes to the Linux kernel, inpublic, with source code publicly available at all times. The rest ofAndroid is developed in private, with source code released publiclywhen a new version is released. Typically Google collaborates with ahardware manufacturer to produce a flagship device (part of theGoogle Nexus series) featuring the new version of Android, then makesthe source code available after that device has been released.In early 2011, Google chose to temporarily withhold the Android sourcecode to the tablet-only Honeycomb release, the reason, according toAndy Rubin in an official Android blog post, was because Honeycombwas rushed for production of the Motorola Xoom, and they did not wantthird parties creating a "really bad user experience" by attempting toput onto smart phones a version of Android intended for tablets. Thesource code was once again made available in November 2011 withthe release of Android 4.0.
Copyrights and patents:Further information: Oracle v. GoogleBoth Android and Android phone manufacturers have been the target of numerous patentlawsuits. On August 12, 2010, Oracle sued Google over claimed infringement of copyrightsand patents related to the Java programming language. Oracle originally sought damagesup to $6.1 billion, but this valuation was rejected by a federal judge who asked Oracle torevise the estimate. In response, Google submitted multiple lines of defense, counterclaimingthat Android did not infringe on Oracles patents or copyright, that Oracles patents wereinvalid, and several other defenses. They said that Android is based on Apache Harmony, aclean room implementation of the Java class libraries, and an independently developedvirtual machine called Dalvik. In May 2012 the jury in this case found that Google did notinfringe on Oracles patents, and the trial judge ruled that the structure of the Java APIs usedby Google was not copyrightable.In addition to lawsuits against Google directly, various proxy wars have been waged againstmanufacturers of Android devices. Both Apple and Microsoft have sued severalmanufacturers for patent infringement, with Apples ongoing legal action against Samsungbeing a particularly high-profile case. In October 2011 Microsoft said they had signed patentlicense agreements with ten Android device manufacturers, whose products account for 55%of the worldwide revenue for Android devices. These include Samsung and HTC.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 patentlitigation, rather than innovating and competing with better products and services. In 2011-2,Google purchased Motorola Mobility for US$12.5 billion, which was viewed in part as adefensive measure to protect Android, since Motorola Mobility held more than 17,000patents. In December 2011 Google bought over a thousand patents from IBM.