1 page.title=Compatibility Program Overview 2 @jd:body 3 4 <!-- 5 Copyright 2010 The Android Open Source Project 6 7 Licensed under the Apache License, Version 2.0 (the "License"); 8 you may not use this file except in compliance with the License. 9 You may obtain a copy of the License at 10 11 http://www.apache.org/licenses/LICENSE-2.0 12 13 Unless required by applicable law or agreed to in writing, software 14 distributed under the License is distributed on an "AS IS" BASIS, 15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 See the License for the specific language governing permissions and 17 limitations under the License. 18 --> 19 20 <p>The Android compatibility program makes it easy for mobile device 21 manufacturers to develop compatible Android devices.</p> 22 <h1 id="program-goals">Program goals</h1> 23 <p>The Android compatibility program works for the benefit of the entire 24 Android community, including users, developers, and device manufacturers.</p> 25 <p>Each group depends on the others. Users want a wide selection of devices 26 and great apps; great apps come from developers motivated by a large market 27 for their apps with many devices in users' hands; device manufacturers rely 28 on a wide variety of great apps to increase their products' value for 29 consumers.</p> 30 <p>Our goals were designed to benefit each of these groups:</p> 31 <ul> 32 <li> 33 <p><em>Provide a consistent application and hardware environment to application 34 developers.</em> 35 Without a strong compatibility standard, devices can vary so 36 greatly that developers must design different versions of their applications 37 for different devices. The compatibility program provides a precise definition 38 of what developers can expect from a compatible device in terms of APIs and 39 capabilities. Developers can use this information to make good design 40 decisions, and be confident that their apps will run well on any compatible 41 device.</p> 42 </li> 43 <li> 44 <p><em>Enable a consistent application experience for consumers.</em> 45 If an application runs well on one compatible Android device, it should run well on 46 any other device that is compatible with the same Android platform version. 47 Android devices will differ in hardware and software capabilities, so the 48 compatibility program also provides the tools needed for distribution systems 49 such as Google Play to implement appropriate filtering. This means that 50 users can only see applications which they can actually run.</p> 51 </li> 52 <li> 53 <p><em>Enable device manufacturers to differentiate while being 54 compatible.</em> 55 The Android compatibility program focuses on the aspects of 56 Android relevant to running third-party applications, which allows device 57 manufacturers the flexibility to create unique devices that are nonetheless 58 compatible.</p> 59 </li> 60 <li> 61 <p><em>Minimize costs and overhead associated with compatibility.</em> 62 Ensuring compatibility should be easy and inexpensive to 63 device manufacturers. The testing tool (CTS) is free, open source, and 64 available for <a href="downloads.html">download</a>. 65 CTS is designed to be used for continuous self-testing 66 during the device development process to eliminate the cost of changing your 67 workflow or sending your device to a third party for testing. Meanwhile, there 68 are no required certifications, and thus no corresponding costs and 69 fees.</p> 70 </li> 71 </ul> 72 <p>The Android compatibility program consists of three key components:</p> 73 <ul> 74 <li>The source code to the Android software stack</li> 75 <li>The Compatilbility Definition Document, representing the "policy" aspect of compatibility</li> 76 <li>The Compatilbility Test Suite, representing the "mechanism" of compatibility</li> 77 </ul> 78 <p>Just as each version of the Android platform exists in a separate branch in 79 the source code tree, there is a separate CTS and CDD for each version as 80 well. The CDD, CTS, and source code are -- along with your hardware and your 81 software customizations -- everything you need to create a compatible device.</p> 82 <h1 id="compatibility-definition-document-cdd">Compatibility Definition Document (CDD)</h1> 83 <p>For each release of the Android platform, a detailed Compatibility 84 Definition Document (CDD) will be provided. The CDD represents the "policy" 85 aspect of Android compatibility.</p> 86 <p>No test suite, including CTS, can truly be comprehensive. For instance, the 87 CTS includes a test that checks for the presence and correct behavior of 88 OpenGL graphics APIs, but no software test can verify that the graphics 89 actually appear correctly on the screen. More generally, it's impossible to 90 test the presence of hardware features such as keyboards, display density, 91 WiFi, and Bluetooth.</p> 92 <p>The CDD's role is to codify and clarify specific requirements, and 93 eliminate ambiguity. The CDD does not attempt to be comprehensive. Since 94 Android is a single corpus of open-source code, the code itself is the 95 comprehensive "specification" of the platform and its APIs. The CDD acts as a 96 "hub", referencing other content (such as SDK API documentation) that provides 97 a framework in which the Android source code may be used so that the end 98 result is a compatible system.</p> 99 <p>If you want to build a device compatible with a given Android version, 100 start by checking out the source code for that version, and then read the 101 corresponding CDD and stay within its guidelines. For additional details, 102 simply examine <a href="/compatibility/android-4.3-cdd.pdf">the latest CDD</a>.</p> 103 <h1 id="compatibility-test-suite-cts">Compatibility Test Suite (CTS)</h1> 104 <p>The CTS is a free, commercial-grade test suite, available for 105 <a href="downloads.html">download</a>. 106 The CTS represents the "mechanism" of compatibility.</p> 107 <p>The CTS runs on a desktop machine and executes test cases directly on 108 attached devices or an emulator. The CTS is a set of unit tests designed to be 109 integrated into the daily workflow (such as via a continuous build system) of 110 the engineers building a device. Its intent is to reveal incompatibilities 111 early on, and ensure that the software remains compatible throughout the 112 development process.</p> 113 <h1 id="compatibility-test-suite-verifier-cts-verifier">Compatibility Test Suite Verifier (CTS Verifier)</h1> 114 <p>The Compatibility Test Suite Verifier (CTS Verifier) is a supplement to the 115 Compatibility Test Suite (CTS), available for <a href="downloads.html">download</a>. 116 CTS Verifier provides tests for APIs and functions that cannot be tested on a 117 stationary device without manual input (e.g. audio quality, accelerometer, etc).</p> 118 <p>For details on the CTS, consult the <a href="cts-intro.html">CTS introduction</a>.</p> 119 120 121
