en/compatibility/overview.html - platform/docs/source.android.com - Git at Google

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 <p>Android's purpose is to establish an open platform for developers to build
 innovative apps.</p>
 <ul>
 <li>The Android Compatibility program defines technical details of the
 Android platform and provides tools for OEMs to ensure developer applications
 run on a variety of devices.</li>
 <li>The Android SDK provides built-in tools for developers to clearly state the
 device features required by their applications.</li>
 <li>Google Play shows applications only to those devices that can properly run
 those applications.</li>
 </ul>

 <h2 id="why-build-compatible-android-devices">Why build compatible Android
 devices?</h2>

 <h3 id="users-want-a-customizable-device">Users want customizable devices</h3>

 <div class="attempt-right">
   <img src="images/compat-ecosystem.png" alt="Compatibility ecosystem" id="figure1" />
   <p class="img-caption">
     <strong>Figure 1.</strong> The Android ecosystem thrives with device compatibility
   </p>
 </div>

 <p>A mobile phone is a highly personal, always-on, always-present gateway to
 the Internet. We haven't met a user yet who didn't want to customize it by
 extending its functionality. That's why Android was designed as a robust
 platform for running aftermarket applications.</p>

 <h3 id="developers-outnumber-us-all">Developers outnumber us all</h3>
 <p>No device manufacturer can write all the software a user could conceivably
 need. We need third-party developers to write the apps users want, so the
 Android Open Source Project (AOSP) aims to make application development as easy
 and open as possible.</p>

 <h3 id="everyone-needs-a-common-ecosystem">Everyone needs a common ecosystem</h3>
 <p>Every line of code developers write to work around a bug is a line of code
 that didn't add a new feature. The more compatible mobile devices are, the more
 applications we'll have to run on those devices. By building a fully compatible
 Android device, you benefit from the huge pool of apps written for Android while
 increasing the incentive for developers to build more apps.</p>

 <h2 id="program-goals">Program goals</h2>

 <p>The Android compatibility program works for the benefit of the entire
 Android community, including users, developers, and device manufacturers.</p>
 <p>Each group depends on the others. Users want a wide selection of devices
 and great apps; great apps come from developers motivated by a large market
 for their apps with many devices in users' hands; device manufacturers rely
 on a wide variety of great apps to increase their products' value for
 consumers.</p>
 <p>Our goals were designed to benefit each of these groups:</p>
 <ul>
 <li>
 <p><em>Provide a consistent application and hardware environment to application
 developers.</em>
     Without a strong compatibility standard, devices can vary so
 greatly that developers must design different versions of their applications
 for different devices. The compatibility program provides a precise definition
 of what developers can expect from a compatible device in terms of APIs and
 capabilities. Developers can use this information to make good design
 decisions, and be confident that their apps will run well on any compatible
 device.</p>
 </li>
 <li>
 <p><em>Enable a consistent application experience for consumers.</em>
     If an application runs well on one compatible Android device, it should run well on
 any other device that is compatible with the same Android platform version.
 Android devices will differ in hardware and software capabilities, so the
 compatibility program also provides the tools needed for distribution systems
 such as Google Play to implement appropriate filtering. This means
 users see only the applications they can actually run.</p>
 </li>
 <li>
 <p><em>Enable device manufacturers to differentiate while being
 compatible.</em>
     The Android compatibility program focuses on the aspects of
 Android relevant to running third-party applications, which allows device
 manufacturers the flexibility to create unique devices that are nonetheless
 compatible.</p>
 </li>
 <li>
 <p><em>Minimize costs and overhead associated with compatibility.</em>
     Ensuring compatibility should be easy and inexpensive to
 device manufacturers. The testing tool is free, open source, and
 available for <a href="cts/downloads.html">download</a>.
 It is designed to be used for continuous self-testing
 during the device development process to eliminate the cost of changing your
 workflow or sending your device to a third party for testing. Meanwhile, there
 are no required certifications, and thus no corresponding costs and
 fees.</p>
 </li>
 </ul>

 <h2 id="program-components">Program components</h2>

 <p>The Android compatibility program consists of three key components:</p>
 <ul>
 <li>The <a href="https://android.googlesource.com/">Android Open Source Project</a> source code</li>
 <li>The <a href="cdd.html">Compatibility Definition Document (CDD)<a/>, representing the "policy" aspect of compatibility</li>
 <li>The <a href="cts/index.html">Compatibility Test Suite (CTS)</a>, representing the "mechanism" of compatibility</li>
 </ul>

 <h2 id="android-compatibility-is-free-and-its-easy">Android compatibility is
 free, and it's easy</h2>
 <p>To build an Android-compatible mobile device, follow this three-step
 process:</p>
 <ol>
 <li><em>Obtain the <a href="/setup/index.html">Android software source
 code</a></em>. This is the source code for the Android platform that you port
 to your hardware.</li>
 <li><em>Comply with the Android Compatibility Definition Document (CDD)</em>
 (<a href="/compatibility/android-cdd.pdf">PDF</a>, <a
 href="/compatibility/android-cdd.html">HTML</a>). The CDD enumerates
 the software and hardware requirements of a compatible Android device.</li>
 <li><em>Pass the <a href="/compatibility/cts/">Compatibility
 Test Suite (CTS)</a></em>. Use the CTS as an ongoing aid to evaluate
 compatibility during the development process.</li> </ol>

 <p>After complying with the CDD and passing the CTS, your device is Android
 compatible, meaning Android apps in the ecosystem provide a consistent
 experience when running on your device. For details about the Android
 compatibility program, see the <a href="overview.html">program overview</a>.</p>

 <p>Just as each version of the Android platform exists in a separate branch in
 the source code tree, there is a separate CTS and CDD for each version as
 well. The CDD, CTS, and source code are &mdash; along with your hardware and your
 software customizations &mdash; everything you need to create a compatible device.</p>

 <h2 id="licensing-gms">Licensing Google Mobile Services (GMS)</h2>
 <p>After building an Android compatible device, consider licensing Google Mobile
 Services (GMS), Google’s proprietary suite of apps (Google Play, YouTube, Google
 Maps, Gmail, and more) that run on top of Android. GMS is not part of the
 Android Open Source Project and is available only through a license with Google.
 For information on how to request a GMS license, see our
 <a href="/setup/community#for-business-inquiries">Contact/Community</a> page.</p>

   </body>
 </html>
	<html devsite>
	<head>
	<title>Android Compatibility Program Overview</title>
	<meta name="project_path" value="/_project.yaml" />
	<meta name="book_path" value="/_book.yaml" />
	</head>
	<body>
	<!--
	Copyright 2017 The Android Open Source Project

	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->



	<p>Android's purpose is to establish an open platform for developers to build
	innovative apps.</p>
	<ul>
	<li>The Android Compatibility program defines technical details of the
	Android platform and provides tools for OEMs to ensure developer applications
	run on a variety of devices.</li>
	<li>The Android SDK provides built-in tools for developers to clearly state the
	device features required by their applications.</li>
	<li>Google Play shows applications only to those devices that can properly run
	those applications.</li>
	</ul>

	<h2 id="why-build-compatible-android-devices">Why build compatible Android
	devices?</h2>

	<h3 id="users-want-a-customizable-device">Users want customizable devices</h3>

	<div class="attempt-right">
	<img src="images/compat-ecosystem.png" alt="Compatibility ecosystem" id="figure1" />
	<p class="img-caption">
	<strong>Figure 1.</strong> The Android ecosystem thrives with device compatibility
	</p>
	</div>

	<p>A mobile phone is a highly personal, always-on, always-present gateway to
	the Internet. We haven't met a user yet who didn't want to customize it by
	extending its functionality. That's why Android was designed as a robust
	platform for running aftermarket applications.</p>

	<h3 id="developers-outnumber-us-all">Developers outnumber us all</h3>
	<p>No device manufacturer can write all the software a user could conceivably
	need. We need third-party developers to write the apps users want, so the
	Android Open Source Project (AOSP) aims to make application development as easy
	and open as possible.</p>

	<h3 id="everyone-needs-a-common-ecosystem">Everyone needs a common ecosystem</h3>
	<p>Every line of code developers write to work around a bug is a line of code
	that didn't add a new feature. The more compatible mobile devices are, the more
	applications we'll have to run on those devices. By building a fully compatible
	Android device, you benefit from the huge pool of apps written for Android while
	increasing the incentive for developers to build more apps.</p>

	<h2 id="program-goals">Program goals</h2>

	<p>The Android compatibility program works for the benefit of the entire
	Android community, including users, developers, and device manufacturers.</p>
	<p>Each group depends on the others. Users want a wide selection of devices
	and great apps; great apps come from developers motivated by a large market
	for their apps with many devices in users' hands; device manufacturers rely
	on a wide variety of great apps to increase their products' value for
	consumers.</p>
	<p>Our goals were designed to benefit each of these groups:</p>
	<ul>
	<li>
	<p><em>Provide a consistent application and hardware environment to application
	developers.</em>
	Without a strong compatibility standard, devices can vary so
	greatly that developers must design different versions of their applications
	for different devices. The compatibility program provides a precise definition
	of what developers can expect from a compatible device in terms of APIs and
	capabilities. Developers can use this information to make good design
	decisions, and be confident that their apps will run well on any compatible
	device.</p>
	</li>
	<li>
	<p><em>Enable a consistent application experience for consumers.</em>
	If an application runs well on one compatible Android device, it should run well on
	any other device that is compatible with the same Android platform version.
	Android devices will differ in hardware and software capabilities, so the
	compatibility program also provides the tools needed for distribution systems
	such as Google Play to implement appropriate filtering. This means
	users see only the applications they can actually run.</p>
	</li>
	<li>
	<p><em>Enable device manufacturers to differentiate while being
	compatible.</em>
	The Android compatibility program focuses on the aspects of
	Android relevant to running third-party applications, which allows device
	manufacturers the flexibility to create unique devices that are nonetheless
	compatible.</p>
	</li>
	<li>
	<p><em>Minimize costs and overhead associated with compatibility.</em>
	Ensuring compatibility should be easy and inexpensive to
	device manufacturers. The testing tool is free, open source, and
	available for <a href="cts/downloads.html">download</a>.
	It is designed to be used for continuous self-testing
	during the device development process to eliminate the cost of changing your
	workflow or sending your device to a third party for testing. Meanwhile, there
	are no required certifications, and thus no corresponding costs and
	fees.</p>
	</li>
	</ul>

	<h2 id="program-components">Program components</h2>

	<p>The Android compatibility program consists of three key components:</p>
	<ul>
	<li>The <a href="https://android.googlesource.com/">Android Open Source Project</a> source code</li>
	<li>The <a href="cdd.html">Compatibility Definition Document (CDD)<a/>, representing the "policy" aspect of compatibility</li>
	<li>The <a href="cts/index.html">Compatibility Test Suite (CTS)</a>, representing the "mechanism" of compatibility</li>
	</ul>

	<h2 id="android-compatibility-is-free-and-its-easy">Android compatibility is
	free, and it's easy</h2>
	<p>To build an Android-compatible mobile device, follow this three-step
	process:</p>
	<ol>
	<li><em>Obtain the <a href="/setup/index.html">Android software source
	code</a></em>. This is the source code for the Android platform that you port
	to your hardware.</li>
	<li><em>Comply with the Android Compatibility Definition Document (CDD)</em>
	(<a href="/compatibility/android-cdd.pdf">PDF</a>, <a
	href="/compatibility/android-cdd.html">HTML</a>). The CDD enumerates
	the software and hardware requirements of a compatible Android device.</li>
	<li><em>Pass the <a href="/compatibility/cts/">Compatibility
	Test Suite (CTS)</a></em>. Use the CTS as an ongoing aid to evaluate
	compatibility during the development process.</li> </ol>

	<p>After complying with the CDD and passing the CTS, your device is Android
	compatible, meaning Android apps in the ecosystem provide a consistent
	experience when running on your device. For details about the Android
	compatibility program, see the <a href="overview.html">program overview</a>.</p>

	<p>Just as each version of the Android platform exists in a separate branch in
	the source code tree, there is a separate CTS and CDD for each version as
	well. The CDD, CTS, and source code are — along with your hardware and your
	software customizations — everything you need to create a compatible device.</p>

	<h2 id="licensing-gms">Licensing Google Mobile Services (GMS)</h2>
	<p>After building an Android compatible device, consider licensing Google Mobile
	Services (GMS), Google’s proprietary suite of apps (Google Play, YouTube, Google
	Maps, Gmail, and more) that run on top of Android. GMS is not part of the
	Android Open Source Project and is available only through a license with Google.
	For information on how to request a GMS license, see our
	<a href="/setup/community#for-business-inquiries">Contact/Community</a> page.</p>

	</body>
	</html>