1 page.title=Compatibility Program Overview 2 doc.type=compatibility 3 @jd:body 4 <p>The Android compatibility program makes it easy for mobile device 5 manufacturers to develop compatible Android devices.</p> 6 <h3>Program goals</h3> 7 <p>The Android compatibility program works for the benefit of the entire 8 Android community, including users, developers, and device manufacturers.</p> 9 <p>Each group depends on the others. Users want a wide selection of devices 10 and great apps; great apps come from developers motivated by a large market 11 for their apps with many devices in users' hands; device manufacturers rely 12 on a wide variety of great apps to increase their products' value for 13 consumers.</p> 14 <p>Our goals were designed to benefit each of these groups:</p> 15 <ul> 16 <li><b>Provide a consistent application and hardware environment to application 17 developers.</b><p>Without a strong compatibility standard, devices can vary so 18 greatly that developers must design different versions of their applications 19 for different devices. The compatibility program provides a precise definition 20 of what developers can expect from a compatible device in terms of APIs and 21 capabilities. Developers can use this information to make good design 22 decisions, and be confident that their apps will run well on any compatible 23 device.</p></li> 24 <li><b>Enable a consistent application experience for consumers.</b><p>If an 25 application runs well on one compatible Android device, it should run well on 26 any other device that is compatible with the same Android platform version. 27 Android devices will differ in hardware and software capabilities, so the 28 compatibility program also provides the tools needed for distribution systems 29 such as Android Market to implement appropriate filtering. This means that 30 users can only see applications which they can actually run.</p></li> 31 <li><b>Enable device manufacturers to differentiate while being 32 compatible.</b><p>The Android compatibility program focuses on the aspects of 33 Android relevant to running third-party applications, which allows device 34 manufacturers the flexibility to create unique devices that are nonetheless 35 compatible.</p></li> 36 <li><b>Minimize costs and overhead associated with 37 compatibility.</b><p>Ensuring compatibility should be easy and inexpensive to 38 device manufacturers. The testing tool (CTS) is free and will soon be available 39 in open source. CTS is designed to be used for continuous self-testing during 40 the device development process to eliminate the cost of changing your workflow 41 or sending your device to a third party for testing. Meanwhile, there are no 42 required certifications, and thus no corresponding costs and fees.</p></li> 43 </ul> 44 <p>The Android compatibility program consists of three key components:</p> 45 <ul> 46 <li>The source code to the Android software stack</li> 47 <li>The Compatilbility Definition Document, representing the "policy" 48 aspect of compatibility</li> 49 <li>The Compatilbility Test Suite, representing the "mechanism" of compatibility</li> 50 </ul> 51 <p>Just as each version of the Android platform exists in a separate branch in 52 the source code tree, there is a separate CTS and CDD for each version as 53 well. The CDD, CTS, and source code are -- along with your hardware and your 54 software customizations -- everything you need to create a compatible device.</p> 55 56 <h3>Compatibility Definition Document (CDD)</h3> 57 <p>For each release of the Android platform, a detailed Compatibility 58 Definition Document (CDD) will be provided. The CDD represents the "policy" 59 aspect of Android compatibility.</p> 60 <p>No test suite, including CTS, can truly be comprehensive. For instance, the 61 CTS includes a test that checks for the presence and correct behavior of 62 OpenGL graphics APIs, but no software test can verify that the graphics 63 actually appear correctly on the screen. More generally, it's impossible to 64 test the presence of hardware features such as keyboards, display density, 65 WiFi, and Bluetooth.</p> 66 <p>The CDD's role is to codify and clarify specific requirements, and 67 eliminate ambiguity. The CDD does not attempt to be comprehensive. Since 68 Android is a single corpus of open-source code, the code itself is the 69 comprehensive "specification" of the platform and its APIs. The CDD acts as a 70 "hub", referencing other content (such as SDK API documentation) that provides 71 a framework in which the Android source code may be used so that the end 72 result is a compatible system.</p> 73 <p>If you want to build a device compatible with a given Android version, 74 start by checking out the source code for that version, and then read the 75 corresponding CDD and stay within its guidelines. For additional details, 76 simply examine <a href="">the latest CDD</a>.</p> 77 78 <h3>Compatibility Test Suite (CTS)</h3> 79 <p>The CTS is a free, commercial-grade test suite, available along with the 80 Android source code. The CTS represents the "mechanism" of compatibility.</p> 81 <p>The CTS runs on a desktop machine and executes test cases directly on 82 attached devices or an emulator. The CTS is a set of unit tests designed to be 83 integrated into the daily workflow (such as via a continuous build system) of 84 the engineers building a device. Its intent is to reveal incompatibilities 85 early on, and ensure that the software remains compatible throughout the 86 development process.</p> 87 <p>For details on the CTS, consult the <a 88 href="{@docRoot}compatibility/cts-intro.html">CTS introduction</a>.</p> 89
