Technologically, Android includes middleware and key applications, and uses a modified version of the Linux kernel. It was initially developed by Android Inc., a firm later purchased by Google, and lately by the Open Handset Alliance. It allows developers to write managed code in the Java language, controlling the device via Google-developed Java libraries.
The Android operating system software stack consists of Java applications running on a Java based object oriented application framework on top of Java core libraries running on a Dalvik virtual machine featuring JIT compilation. Libraries written in C include the surface manager, OpenCore media framework, SQLite relational database management system, OpenGL ES 2.0 3D graphics API, WebKit layout engine, SGL graphics engine, SSL, and Bionic libc. The Android operating system consists of 12 million lines of code including 3 million lines of XML, 2.8 million lines of C, and 2.1 million lines of Java.
The unveiling of the Android distribution on 5 November 2007 was announced with the founding of the Open Handset Alliance, a consortium of 71 hardware, software, and telecom companies devoted to advancing open standards for mobile devices. Google released most of the Android code under the Apache License, a free software and open source license.
According to NPD Group, unit sales for Android OS smartphones ranked second among all smartphone OS handsets sold in the U.S. in the first quarter of 2010. BlackBerry OS and iOS ranked first and third respectively.
In July 2005, Google acquired Android, Inc., a small startup company based in Palo Alto, California, USA. Android's co-founders who went to work at Google included Andy Rubin (co-founder of Danger), Rich Miner (co-founder of Wildfire Communications, Inc.), Nick Sears (once VP at T-Mobile), and Chris White (headed design and interface development at WebTV). At the time, little was known about the functions of Android, Inc. other than that they made software for mobile phones. This began rumors that Google was planning to enter the mobile phone market.[http://en.wikipedia.org/wiki/Wikipedia:Citation_needed ]
At Google, the team led by Rubin developed a mobile device platform powered by the Linux kernel which they marketed to handset makers and carriers on the premise of providing a flexible, upgradeable system. It was reported that Google had already 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. More speculation that Google would be entering the mobile-phone market came in December 2006. 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. More speculation followed reporting that as Google was defining technical specifications, it was showing prototypes to cell phone manufacturers and network operators.
Open Handset AllianceEdit
Main article: Open Handset Alliance"Today's announcement is more ambitious than any single 'Google Phone' that the press has been speculating about over the past few weeks. Our vision is that the powerful platform we're unveiling will power thousands of different phone models." Eric Schmidt, Google Chairman/CEOOn November 5, 2007, the Open Handset Alliance, a consortium of several companies which include Texas Instruments, Broadcom Corporation, Google, HTC, Intel, LG, Marvell Technology Group, Motorola, Nvidia, Qualcomm, Samsung Electronics, Sprint Nextel and T-Mobile was unveiled with the goal to develop open standards for mobile devices.Along with the formation of the Open Handset Alliance, the OHA also unveiled their first product, Android, a mobile device platform built on the Linux kernel version 2.6.
On 9 December 2008, it was announced that 14 new members would be joining the Android project, including ARM Holdings, Atheros Communications, Asustek Computer Inc, Garmin Ltd, Softbank, Sony Ericsson, Toshiba Corp, and Vodafone Group Plc.
With the exception of brief update periods, Android has been available as open source since 21 October 2008. Google opened the entire source code (including network and telephony stacks) under an Apache License.
With the Apache License, vendors can add proprietary extensions without submitting those back to the open source community.
The first Android statue placed outside the Googleplex.A cupcake was placed beside the Android at the Googleplex to commemorate the release of Android version 1.5, codenamed 'Cupcake'.Android has seen a number of updates since its original release. These updates to the base operating system typically fix bugs and add new features.
|1.1||Released 9 February 2009|
Based on Linux Kernel 2.6.27
|On 30 April 2009, the official 1.5 (Cupcake) update for Android was released. There were several new features and UI updates included in the 1.5 update:*Ability to record and watch videos through camcorder mode
Based on Linux Kernel 2.6.29
|On 15 September 2009, the 1.6 (Donut) SDK was released. Included in the update were:*An improved Android Market experience
Based on Linux Kernel 2.6.29
|On 26 October 2009 the 2.0 (Eclair) SDK was released. Among the changes were:*Optimized hardware speed
The 2.0.1 SDK was released on 3 December 2009.
The 2.1 SDK was released on 12 January 2010.
Based on Linux Kernel 2.6.32
|On 20 May 2010 the 2.2 (Froyo) SDK was released. Changes included:*General Android OS speed, memory, and performance optimizations
Based on Linux Kernel 2.6.33 or 34
|Confirmed new features:
Unconfirmed new features:
|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, and WiMAX.|
|Messaging||SMS and MMS are available forms of messaging, including threaded text messaging and now Android Cloud to Device Messaging Framework(C2DM) is also a part of Android Push Messaging service.|
|Java support||While Android applications are written in Java, there's no Java Virtual Machine in the platform and Java byte code is not executed. Java classes get recompiled into Dalvik executable and run on Dalvik virtual machine. Dalvik is a specialized virtual machine designed specifically for Android and optimized for battery-powered mobile devices with limited memory and CPU. Android does not support J2ME, like some other mobile operating systems.|
|Media support||Android supports the following audio/video/still media formats: 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, WAV, JPEG, PNG, GIF, BMP.|
|Additional hardware support||Android can use video/still cameras, touchscreens, GPS, accelerometers, magnetometers, accelerated 2D bit blits (with hardware orientation, scaling, pixel format conversion) and accelerated 3D graphics.|
|Development environment||Includes a device emulator, tools for debugging, memory and performance profiling, and a plugin for the Eclipse IDE.|
|Market||Like many phone-based application stores, the Android Market is a catalog of applications that can be downloaded and installed to target hardware over-the-air, without the use of a PC. Originally only free applications were supported. Paid-for applications have been available on the Android Market in the United States since 19 February 2009. The Android Market has been expanding rapidly. As of April 30, 2010, it had over 50,000 Android applications for download.|
|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). Google has since released an update for the Nexus One and the Motorola Droid which enables multi-touch natively.|
|Bluetooth||Support for A2DP and AVRCP were added in version 1.5; sending files (OPP) and accessing the phone book (PBAP) were added in version 2.0; and voice dialing and sending contacts between phones were added in version 2.2.|
|Videocalling||Not supported by default but as seen with the HTC Evo 4G, which runs Sense. ]|
|Multitasking||Multitasking of applications is available.|
The first phone to run the Android operating system was the HTC Dream, released on 22 October 2008.
Early Android device.The early feedback on developing applications for the Android platform was mixed. Issues cited include bugs, lack of documentation, inadequate QA infrastructure, and no public issue-tracking system. (Google announced an issue tracker on 18 January 2008.) In December 2007, MergeLab mobile startup founder Adam MacBeth stated, "Functionality is not there, is poorly documented or just doesn't work... It's clearly not ready for prime time." Despite this, Android-targeted applications began to appear the week after the platform was announced. The first publicly available application was the Snake game. The Android Dev Phone is a SIM-unlocked and hardware-unlocked device that is designed for advanced developers. While developers can use regular consumer devices purchased at retail to test and use their applications, some developers may choose not to use a retail device, preferring an unlocked or no-contract device.
Software development kitEdit
The Android SDK includes a comprehensive set of development tools. These include a debugger, libraries, a handset emulator (based on QEMU), documentation, sample code, and tutorials. Currently supported development platforms include x86-architecture computers running Linux (any modern desktop Linux distribution), Mac OS X 10.4.8 or later, Windows XP or Vista. Requirements also include Java Development Kit, Apache Ant, and Python 2.2 or later. The officially supported integrated development environment (IDE) is Eclipse (3.2 or later) using the Android Development Tools (ADT) Plugin, though developers may use any text editor to edit Java and XML files then use command line tools to create, build and debug Android applications as well as control attached Android devices (e.g., triggering a reboot, installing software package(s) remotely).
A preview release of the Android software development kit (SDK) was released on 12 November 2007. On 15 July 2008, the Android Developer Challenge Team accidentally sent an email to all entrants in the Android Developer Challenge announcing that a new release of the SDK was available in a "private" download area. The email was intended for winners of the first round of the Android Developer Challenge. The revelation that Google was supplying new SDK releases to some developers and not others (and keeping this arrangement private) has led to widely reported frustration within the Android developer community.
On 18 August 2008 the Android 0.9 SDK beta was released. This release provided an updated and extended API, improved development tools and an updated design for the home screen. Detailed instructions for upgrading are available to those already working with an earlier release.On 23 September 2008 the Android 1.0 SDK (Release 1) was released. According to the release notes, it included "mainly bug fixes, although some smaller features were added". It also included several API changes from the 0.9 version.
On 9 March 2009, Google released version 1.1 for the Android dev phone. While there are a few aesthetic updates, a few crucial updates include support for "search by voice, priced applications, alarm clock fixes, sending gmail freeze fix, fixes mail notifications and refreshing intervals, and now the maps show business reviews". Another important update is that Dev phones can now access paid applications and developers can now see them on the Android Market.
In the middle of May 2009, Google released version 1.5 (Cupcake) of the Android OS and SDK. This update included many new features including video recording, support for the stereo bluetooth profile, a customizable onscreen keyboard system and voice recognition. This release also opened up the AppWidget framework to third party developers allowing anyone to create their own home screen widgets.
In September 2009 the "Donut" version (1.6) was released which featured better search, battery usage indicator and VPN control applet. New platform technologies included Text to Speech engine (not available on all phones), Gestures & Accessibility framework.
Android Applications are packaged in .apk format and stored under /data/app folder on the Android OS. The user can run the command adb root to access this folder as only the root has permissions to access this folder.
Android Developer ChallengeEdit
The Android Developer Challenge was a competition for the most innovative application for Android. Google offered prizes totaling 10 million US dollars, distributed between ADC I and ADC II. ADC I accepted submissions from 2 January to 14 April 2008. The 50 most promising entries, announced on 12 May 2008, each received a $25,000 award to fund further development. It ended in early September with the announcement of ten teams that received $275,000 each, and ten teams that received $100,000 each. ADC II was announced on 27 May 2009. The first round of the ADC II closed on 6 October 2009. The first-round winners of ADC II comprising the top 200 applications were announced on 5 November 2009. Voting for the second round also opened on the same day and ended on November 25. Google announced the top winners of ADC II on November 30, with SweetDreams, What the Doodle!? and WaveSecure being nominated the overall winners of the challenge.
Google has also participated in the Android Market by offering several applications for its services. These applications include 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, Google Translate, Google Shopper, Listen for podcasts and My Tracks, a jogging application.
Third party applicationsEdit
With the growing number of Android handsets, there has also been an increased interest by third party developers to port their applications to the Android operating system. Famous applications that have been converted to the Android operating system include Shazam, Backgrounds, and WeatherBug.
The Android operating system has also been considered important enough by a lot of the most popular internet sites and services to create native android applications. These include MySpace, Facebook, and Twitter.
Libraries written in C and other languages can be compiled to ARM native code and installed using the Android Native Development Kit. Native classes can be called from Java code running under the Dalvik VM using the System.loadLibrary call, which is part of the standard Android Java classes.
Complete applications can be compiled and installed using traditional development tools. The ADB debugger gives a root shell under the Android Emulator which allows native ARM code to be uploaded and executed. ARM code can be compiled using GCC on a standard PC. Running native code is complicated by the fact that Android uses a non-standard C library (known as Bionic). The underlying graphics device is available as a framebuffer at /dev/graphics/fb0. The graphics library that Android uses to arbitrate and control access to this device is called the Skia Graphics Library (SGL), and it has been released under an open source license. Skia has backends for both win32 and Cairo, allowing the development of cross-platform applications, and it is the graphics engine underlying the Google Chrome web browser.
There is a community of open-source enthusiasts that build and share Android-based firmware with a number of customizations and additional features, such as FLAC lossless audio support and the ability to store downloaded applications on the microSD card. This usually involves rooting the device. Rooting lets users load modified firmwares allowing users of older phones to use applications available only on newer releases.
Those firmware packages are updated frequently, incorporate elements of Android functionality that haven't yet been officially released within a carrier-sanctioned firmware, and tend to have fewer limitations. CyanogenMod is one such firmware.
On 24 September 2009, Google issued a cease and desist letter to the modder Cyanogen, citing issues with the re-distribution of Google's closed-source applications within the custom firmware. Even though Android OS is open source, phones come packaged with closed-source Google applications for functionality such as the application store and GPS navigation. Google has asserted that these applications can only be provided through approved distribution channels by licensed distributors. Cyanogen has complied with Google's wishes and is continuing to distribute this mod without the proprietary software. He has provided a method to back up licensed Google applications during the mod's install process and restore them when it is complete.
Android Green is the color of the Android Robot that represents the Android operating system. The print color is PMS 376C and the online hex color is #A4C639, as specified by the Android Brand Guidelines.
The custom typeface of Android is called Norad, only used in the text logo.
In February 2010 ComScore ranked the Android platform as obtaining a 9.0% of the smartphone platform marketshare. This figure was up from an earlier estimate of 5.2% stated in November 2009.
In October, 2009, Gartner Inc. predicted that by 2012, Android would become the world's second most popular smartphone platform, behind Nokia's Symbian OS, which is very popular outside the US. Meanwhile, BlackBerry would fall from 2nd to 5th place, iPhone would remain in 3rd place, and Microsoft's Windows Mobile would remain in 4th place.
Analytics firm Flurry estimates that 250,000 Motorola Droid phones were sold in the United States during the phone's first week in stores.
In May 2010, Android's first quarter US sales surpassed that of the rival iPhone platform. According to a report by the NPD group, Android achieved 28% smartphone sales in the US market, up 8% from the December quarter. The iPhone's sales fell flat at 21% over the same reporting period.
Restrictions and issuesEdit
Google tracks issues and feature requests publicly at Google Code's site.
- Android uses a version of Linux as its kernel (albeit tweaked by Google to fit Android needs and separated from the main Linux kernel tree), but it is not a conventional Linux distribution; it does not have a native X Window System, nor does it support the full set of standard GNU libraries like its system libraries (GNU C Library). This makes it difficult to reuse existing Linux applications or libraries on Android.
- Google no longer maintains the Android code they previously contributed to the Linux kernel, effectively branching kernel code in their own tree, separating their code from Linux. The code which is no longer maintained was deleted in January 2010 from the Linux codebase. However, Google announced in April 2010 that they will employ staff to work with the Linux kernel community.
- Android does not support setting up a network proxy configuration for WiFi connections.
- Android does not support Cisco-compatible IPsec virtual private networks (Layer 2 Tunneling Protocol is supported).
- Android did not support wireless ad hoc networking until Android 2.2 (Froyo).
Issues concerning application developmentEdit
- Android does not use established Java standards, i.e. Java SE and ME. This prevents compatibility among Java applications written for those platforms and those for the Android platform. Android only reuses the Java language syntax, but does not provide the full-class libraries and APIs bundled with Java SE or ME. However, the Myriad Group claim that their new J2Android tool can convert Java MIDlets into Android applications.
- Developers have reported that it is difficult to maintain applications on multiple versions of Android, owing to compatibility issues between versions 1.5 and 1.6, especially the different resolution ratios in use among various Android phones. Such problems were poignantly brought into focus as they were encountered during the ADC2 contest.
- The rapid growth in the number of Android-based phone models with differing hardware capabilities also makes it difficult to develop applications that work on all Android-based phones.. As of May 2010, only 32% of Android phones run the 2.1 version, and 37% still run the 1.5 version
- Garbage collection will slow down programs that demand more memory than Dalvik can optimally manage; thus, responsiveness will suffer noticeably.
- Android does not readily support Bluetooth file exchange, video call or native Java ME, as do other mobile operating systems, such as Symbian OS and Windows Mobile; however, some of these, such as Bluetooth file exchange, may still be achieved with some hacking. Additionally, applications like Qik allow video calling on some models, and video broadcasting on others.