Android 2.3 호환성 정의

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호환성@android.com

목차

1. 소개

이 문서에서는 휴대폰이 Android 2.3과 호환되기 위해 충족해야 하는 요구 사항을 열거합니다.

"해야 한다", "하지 말아야 한다", "필수", "해야 한다", "하지 말아야 한다", "해야 한다", "하지 말아야 한다", "권장한다", "할 수 있다" 및 "선택 사항"의 사용은 IETF 표준에 따릅니다. RFC2119 [ 리소스, 1 ]에 정의되어 있습니다.

이 문서에서 사용된 '기기 구현자' 또는 '구현자'는 Android 2.3을 실행하는 하드웨어/소프트웨어 솔루션을 개발하는 개인 또는 조직입니다. "장치 구현" 또는 "구현"은 그렇게 개발된 하드웨어/소프트웨어 솔루션입니다.

Android 2.3과 호환되는 것으로 간주되려면 기기 구현이 참조를 통해 통합된 모든 문서를 포함하여 이 호환성 정의에 제시된 요구 사항을 충족해야 합니다.

이 정의 또는 섹션 10 에 설명된 소프트웨어 테스트가 명확하지 않거나 모호하거나 불완전한 경우 기존 구현과의 호환성을 보장하는 것은 장치 구현자의 책임입니다. 이러한 이유로 Android 오픈 소스 프로젝트[ 리소스, 3 ]는 Android의 참조이자 선호되는 구현입니다. 기기 구현자는 Android 오픈소스 프로젝트에서 제공되는 '업스트림' 소스 코드를 최대한 기반으로 구현하는 것이 좋습니다. 일부 구성 요소는 가상적으로 대체 구현으로 교체될 수 있지만 소프트웨어 테스트를 통과하는 것이 훨씬 더 어려워지므로 이러한 방식은 권장되지 않습니다. 호환성 테스트 도구 모음을 포함하여 표준 Android 구현과의 완전한 동작 호환성을 보장하는 것은 구현자의 책임입니다. 마지막으로, 이 문서에서는 특정 구성 요소 대체 및 수정을 명시적으로 금지합니다.

이 호환성 정의는 API 레벨 10인 Android의 2.3.3 업데이트에 대응하기 위해 발행되었습니다. 이 정의는 2.3.3 이전의 Android 2.3 버전에 대한 호환성 정의를 폐기하고 대체합니다. (즉, 버전 2.3.1 및 2.3.2는 더 이상 사용되지 않습니다.) Android 2.3을 실행하는 향후 Android 호환 기기는 버전 2.3.3 이상과 함께 출시되어야 합니다.

2. 자원

1. IETF RFC2119 요구 사항 수준: http://www.ietf.org/rfc/rfc2119.txt
2. Android 호환성 프로그램 개요: http://source.android.com/docs/compatibility/index.html
3. Android 오픈소스 프로젝트: http://source.android.com/
4. API 정의 및 문서: http://developer.android.com/reference/packages.html
5. Android 권한 참조: http://developer.android.com/reference/android/Manifest.permission.html
6. android.os.Build 참조: http://developer.android.com/reference/android/os/Build.html
7. Android 2.3에서 허용되는 버전 문자열: http://source.android.com/docs/compatibility/2.3/versions.html
8. android.webkit.WebView 클래스: http://developer.android.com/reference/android/webkit/WebView.html
9. HTML5: http://www.whatwg.org/specs/web-apps/current-work/multipage/
10. HTML5 오프라인 기능: http://dev.w3.org/html5/spec/Overview.html#offline
11. HTML5 비디오 태그: http://dev.w3.org/html5/spec/Overview.html#video
12. HTML5/W3C 위치정보 API: http://www.w3.org/TR/geolocation-API/
13. HTML5/W3C 웹데이터베이스 API: http://www.w3.org/TR/webdatabase/
14. HTML5/W3C IndexedDB API: http://www.w3.org/TR/IndexedDB/
15. Dalvik 가상 머신 사양: dalvik/docs의 Android 소스 코드에서 사용 가능
16. 앱 위젯: http://developer.android.com/guide/practices/ui_guidelines/widget_design.html
17. 알림: http://developer.android.com/guide/topics/ui/notifiers/notifications.html
18. 애플리케이션 리소스: http://code.google.com/android/reference/available-resources.html
19. 상태 표시줄 아이콘 스타일 가이드: http://developer.android.com/guide/practices/ui_guideline /icon_design.html#statusbarstructure
20. 검색 관리자: http://developer.android.com/reference/android/app/SearchManager.html
21. 토스트: http://developer.android.com/reference/android/widget/Toast.html
22. 라이브 배경화면: https://android-developers.googleblog.com/2010/02/live-wallpapers.html
23. 참조 도구 문서(adb, aapt, ddms용): http://developer.android.com/guide/developing/tools/index.html
24. Android APK 파일 설명: http://developer.android.com/guide/topics/fundamentals.html
25. 매니페스트 파일: http://developer.android.com/guide/topics/manifest/manifest-intro.html
26. 원숭이 테스트 도구: https://developer.android.com/studio/test/other-testing-tools/monkey
27. Android 하드웨어 기능 목록: http://developer.android.com/reference/android/content/pm/PackageManager.html
28. 다중 화면 지원: http://developer.android.com/guide/practices/screens_support.html
29. android.util.DisplayMetrics: http://developer.android.com/reference/android/util/DisplayMetrics.html
30. android.content.res.Configuration: http://developer.android.com/reference/android/content/res/Configuration.html
31. 센서 좌표 공간: http://developer.android.com/reference/android/hardware/SensorEvent.html
32. 블루투스 API: http://developer.android.com/reference/android/bluetooth/package-summary.html
33. NDEF 푸시 프로토콜: http://source.android.com/docs/compatibility/ndef-push-protocol.pdf
34. MIFARE MF1S503X: http://www.nxp.com/documents/data_sheet/MF1S503x.pdf
35. MIFARE MF1S703X: http://www.nxp.com/documents/data_sheet/MF1S703x.pdf
36. MIFARE MF0ICU1: http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf
37. MIFARE MF0ICU2: http://www.nxp.com/documents/short_data_sheet/MF0ICU2_SDS.pdf
38. MIFARE AN130511: http://www.nxp.com/documents/application_note/AN130511.pdf
39. MIFARE AN130411: http://www.nxp.com/documents/application_note/AN130411.pdf
40. 카메라 방향 API: http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)
41. android.hardware.Camera: http://developer.android.com/reference/android/hardware/Camera.html
42. Android 보안 및 권한 참조: http://developer.android.com/guide/topics/security/security.html
43. Android용 앱: http://code.google.com/p/apps-for-android

이러한 리소스 중 다수는 Android 2.3 SDK에서 직접 또는 간접적으로 파생되며 해당 SDK 문서의 정보와 기능적으로 동일합니다. 이 호환성 정의 또는 호환성 테스트 도구 모음이 SDK 문서와 일치하지 않는 경우 SDK 문서는 신뢰할 수 있는 것으로 간주됩니다. 위에 포함된 참조 자료에 제공된 모든 기술적 세부 사항은 이 호환성 정의의 일부로 포함된 것으로 간주됩니다.

3. 소프트웨어

Android 플랫폼에는 관리형 API 세트, 기본 API 세트, 인텐트 시스템 및 웹 애플리케이션 API와 같은 소위 "소프트" API 본체가 포함되어 있습니다. 이 섹션에서는 호환성에 필수적인 하드 및 소프트 API는 물론 기타 관련 기술 및 사용자 인터페이스 동작에 대해 자세히 설명합니다. 기기 구현은 이 섹션의 모든 요구사항을 준수해야 합니다(MUST).

3.1. 관리형 API 호환성

관리형(Dalvik 기반) 실행 환경은 Android 애플리케이션의 기본 수단입니다. Android API(애플리케이션 프로그래밍 인터페이스)는 관리형 VM 환경에서 실행되는 애플리케이션에 노출되는 Android 플랫폼 인터페이스 세트입니다. 기기 구현은 Android 2.3 SDK[ 리소스, 4 ]에서 노출하는 모든 문서화된 API의 모든 문서화된 동작을 포함하여 완전한 구현을 제공해야 합니다(MUST).

기기 구현은 이 호환성 정의에서 특별히 허용하는 경우를 제외하고 관리되는 API를 생략하거나, API 인터페이스 또는 서명을 변경하거나, 문서화된 동작에서 벗어나거나, 무작동을 포함해서는 안 됩니다.

이 호환성 정의는 Android에 API가 포함된 일부 하드웨어 유형이 기기 구현에서 생략되도록 허용합니다. 그러한 경우에도 API는 여전히 존재하고 합리적인 방식으로 작동해야 합니다. 이 시나리오에 대한 특정 요구 사항은 섹션 7을 참조하세요.

3.2. 소프트 API 호환성

섹션 3.1의 관리형 API 외에도 Android에는 인텐트, 권한, 애플리케이션 컴파일 시 시행할 수 없는 Android 애플리케이션의 유사한 측면 등의 형태로 중요한 런타임 전용 "소프트" API도 포함되어 있습니다. 이 섹션에서는 Android 2.3과의 호환성에 필요한 "소프트" API 및 시스템 동작을 자세히 설명합니다. 기기 구현은 이 섹션에 제시된 모든 요구사항을 충족해야 합니다(MUST).

3.2.1. 권한

기기 구현자는 권한 참조 페이지[ 리소스, 5 ]에 설명된 대로 모든 권한 상수를 지원하고 시행해야 합니다. 섹션 10에는 Android 보안 모델과 관련된 추가 요구 사항이 나열되어 있습니다.

3.2.2. 빌드 매개변수

Android API에는 현재 장치를 설명하기 위한 android.os.Build 클래스 [ 리소스, 6 ]에 대한 여러 상수가 포함되어 있습니다. 장치 구현 전반에 걸쳐 일관되고 의미 있는 값을 제공하기 위해 아래 표에는 장치 구현이 반드시 준수해야 하는 이러한 값의 형식에 대한 추가 제한 사항이 포함되어 있습니다.

3.2.3. 의도 호환성

Android는 인텐트를 사용하여 애플리케이션 간의 느슨하게 결합된 통합을 달성합니다. 이 섹션에서는 장치 구현에서 반드시 준수해야 하는 인텐트 패턴과 관련된 요구 사항을 설명합니다. '명예'란 기기 구현자가 일치하는 인텐트 필터를 지정하고 지정된 각 인텐트 패턴에 대해 올바른 동작을 바인딩하고 구현하는 Android 활동 또는 서비스를 제공해야 함을 의미합니다.

3.2.3.1. 핵심 애플리케이션 의도

Android 업스트림 프로젝트는 전화 걸기, 달력, 연락처, 음악 플레이어 등과 같은 여러 핵심 애플리케이션을 정의합니다. 장치 구현자는 이러한 애플리케이션을 대체 버전으로 교체할 수 있습니다.

그러나 이러한 대체 버전은 업스트림 프로젝트에서 제공하는 것과 동일한 인텐트 패턴을 존중해야 합니다(MUST). 예를 들어 장치에 대체 음악 플레이어가 포함되어 있는 경우 노래를 선택하려면 타사 애플리케이션에서 발행한 인텐트 패턴을 계속 준수해야 합니다.

다음 애플리케이션은 핵심 Android 시스템 애플리케이션으로 간주됩니다.

• 탁상시계
• 브라우저
• 달력
• 계산자
• 콘택트 렌즈
• 이메일
• 갤러리
• 글로벌서치
• 발사통
• 음악
• 설정

핵심 Android 시스템 애플리케이션에는 '공개'로 간주되는 다양한 활동 또는 서비스 구성 요소가 포함되어 있습니다. 즉, "android:exported" 속성이 없거나 "true" 값을 가질 수 있습니다.

값이 'false'인 android:exported 속성을 통해 비공개로 표시되지 않은 핵심 Android 시스템 앱 중 하나에 정의된 모든 활동 또는 서비스의 경우 기기 구현에는 동일한 인텐트 필터를 구현하는 동일한 유형의 구성요소가 포함되어야 합니다. 패턴을 핵심 Android 시스템 앱으로 사용합니다.

즉, 기기 구현은 핵심 Android 시스템 앱을 대체할 수 있습니다. 하지만 그렇다면 기기 구현은 교체되는 각 핵심 Android 시스템 앱에서 정의한 모든 인텐트 패턴을 지원해야 합니다.

3.2.3.2. 의도 재정의

Android는 확장 가능한 플랫폼이므로 기기 구현자는 섹션 3.2.3.1에서 참조된 각 인텐트 패턴이 타사 애플리케이션에 의해 재정의되도록 허용해야 합니다. 업스트림 Android 오픈소스 프로젝트에서는 기본적으로 이를 허용합니다. 기기 구현자는 시스템 애플리케이션의 이러한 인텐트 패턴 사용에 특별한 권한을 부여하거나 타사 애플리케이션이 이러한 패턴에 바인딩하고 제어권을 취하는 것을 방지해서는 안 됩니다. 이러한 금지 사항에는 사용자가 모두 동일한 인텐트 패턴을 처리하는 여러 애플리케이션 중에서 선택할 수 있도록 하는 "선택자" 사용자 인터페이스를 비활성화하는 것이 포함되지만 이에 국한되지는 않습니다.

3.2.3.3. 인텐트 네임스페이스

기기 구현자는 android.* 네임스페이스의 ACTION, CATEGORY 또는 기타 키 문자열을 사용하여 새로운 인텐트 또는 브로드캐스트 인텐트 패턴을 존중하는 Android 구성요소를 포함해서는 안 됩니다. 기기 구현자는 ACTION, CATEGORY 또는 다른 조직에 속한 패키지 공간의 기타 키 문자열을 사용하여 새로운 인텐트 또는 브로드캐스트 인텐트 패턴을 존중하는 Android 구성요소를 포함해서는 안 됩니다. 기기 구현자는 섹션 3.2.3.1에 나열된 핵심 앱에서 사용하는 인텐트 패턴을 변경하거나 확장하면 안 됩니다.

이 금지 사항은 섹션 3.6의 Java 언어 클래스에 대해 지정된 것과 유사합니다.

3.2.3.4. 방송 의도

타사 애플리케이션은 하드웨어 또는 소프트웨어 환경의 변경 사항을 알리기 위해 특정 인텐트를 브로드캐스트하는 플랫폼을 사용합니다. Android 호환 기기는 적절한 시스템 이벤트에 대한 응답으로 공개 브로드캐스트 인텐트를 브로드캐스트해야 합니다(MUST). 브로드캐스트 의도는 SDK 문서에 설명되어 있습니다.

3.3. 네이티브 API 호환성

Dalvik에서 실행되는 관리 코드는 적절한 장치 하드웨어 아키텍처에 대해 컴파일된 ELF .so 파일로 애플리케이션 .apk 파일에 제공된 네이티브 코드를 호출할 수 있습니다. 네이티브 코드는 기본 프로세서 기술에 크게 의존하므로 Android는 Android NDK의 docs/CPU-ARCH-ABIS.txt 파일에 여러 ABI(애플리케이션 바이너리 인터페이스)를 정의합니다. 기기 구현이 하나 이상의 정의된 ABI와 호환되는 경우 아래와 같이 Android NDK와의 호환성을 구현해야 합니다(SHOULD).

Android ABI 지원을 포함하는 기기 구현은 다음을 충족해야 합니다.

• 표준 JNI(Java Native Interface) 의미 체계를 사용하여 네이티브 코드를 호출하기 위해 관리되는 환경에서 실행되는 코드에 대한 지원을 포함해야 합니다.
• 아래 목록의 각 필수 라이브러리와 소스 호환(예: 헤더 호환) 및 바이너리 호환(ABI용)이어야 합니다.
• android.os.Build.CPU_ABI API를 통해 기기에서 지원하는 기본 ABI(애플리케이션 바이너리 인터페이스)를 정확하게 보고해야 합니다(MUST).
• 최신 버전의 Android NDK docs/CPU-ARCH-ABIS.txt 파일)에 문서화된 ABI만 보고해야 합니다.
• 업스트림 Android 오픈소스 프로젝트에서 사용할 수 있는 소스 코드와 헤더 파일을 사용하여 빌드해야 합니다(SHOULD).

네이티브 코드를 포함하는 앱에서는 다음 네이티브 코드 API를 사용할 수 있어야 합니다(MUST).

• libc(C 라이브러리)
• libm(수학 라이브러리)
• C++에 대한 최소 지원
• JNI 인터페이스
• liblog(안드로이드 로깅)
• libz(Zlib 압축)
• libdl(동적 링커)
• libGLESv1_CM.so(OpenGL ES 1.0)
• libGLESv2.so(OpenGL ES 2.0)
• libEGL.so(네이티브 OpenGL 표면 관리)
• libjnigraphics.so
• libOpenSLES.so(오픈 사운드 라이브러리 오디오 지원)
• libandroid.so(기본 Android 활동 지원)
• 아래 설명된 대로 OpenGL 지원

Android NDK의 향후 릴리스에서는 추가 ABI에 대한 지원이 도입될 수 있습니다. 기기 구현이 기존의 사전 정의된 ABI와 호환되지 않는 경우 ABI에 대한 지원을 전혀 보고하면 안 됩니다(MUST NOT).

네이티브 코드 호환성은 어렵습니다. 이러한 이유로 장치 구현자는 호환성을 보장하기 위해 위에 나열된 라이브러리의 업스트림 구현을 사용하는 것이 매우 강력히 권장된다는 점을 반복해야 합니다.

3.4. 웹 호환성

많은 개발자와 애플리케이션은 사용자 인터페이스를 위해 android.webkit.WebView 클래스[ 리소스, 8 ]의 동작에 의존하므로 WebView 구현은 Android 구현 전체에서 호환되어야 합니다. 마찬가지로, 완벽하고 현대적인 웹 브라우저는 Android 사용자 경험의 핵심입니다. 기기 구현은 업스트림 Android 소프트웨어와 일치하는 android.webkit.WebView 버전을 포함해야 하며(MUST) 아래 설명된 최신 HTML5 지원 브라우저를 포함해야 합니다(MUST).

3.4.1. WebView 호환성

Android 오픈 소스 구현에서는 WebKit 렌더링 엔진을 사용하여 android.webkit.WebView 구현합니다. 웹 렌더링 시스템을 위한 포괄적인 테스트 모음을 개발하는 것은 불가능하기 때문에 장치 구현자는 WebView 구현에서 WebKit의 특정 업스트림 빌드를 사용해야 합니다. 구체적으로:

• 기기 구현의 android.webkit.WebView 구현은 Android 2.3용 업스트림 Android 오픈 소스 트리의 533.1 WebKit 빌드를 기반으로 해야 합니다(MUST). 이 빌드에는 WebView에 대한 특정 기능 세트와 보안 수정 사항이 포함되어 있습니다. 장치 구현자는 WebKit 구현에 대한 사용자 정의를 포함할 수 있습니다. 그러나 이러한 사용자 정의는 렌더링 동작을 포함하여 WebView의 동작을 변경해서는 안 됩니다.
• WebView에서 보고된 사용자 에이전트 문자열은 다음 형식이어야 합니다.
  Mozilla/5.0 (Linux; U; Android $(VERSION); $(LOCALE); $(MODEL) Build/$(BUILD)) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
  • $(VERSION) 문자열의 값은 android.os.Build.VERSION.RELEASE 의 값과 동일해야 합니다.
  • $(LOCALE) 문자열의 값은 국가 코드 및 언어에 대한 ISO 규칙을 따라야 하며(SHOULD) 장치의 현재 구성된 로케일을 참조해야 합니다(SHOULD).
  • $(MODEL) 문자열의 값은 android.os.Build.MODEL 의 값과 동일해야 합니다.
  • $(BUILD) 문자열의 값은 android.os.Build.ID 의 값과 동일해야 합니다.

WebView 구성 요소는 가능한 한 많은 HTML5 [ 리소스, 9 ]에 대한 지원을 포함해야 합니다. 최소한 기기 구현은 WebView에서 HTML5와 연결된 다음 API 각각을 지원해야 합니다(MUST).

• 애플리케이션 캐시/오프라인 작업 [ 리소스, 10 ]
• <video> 태그 [ 리소스, 11 ]
• 위치정보 [ 자료, 12 ]

또한 기기 구현은 HTML5/W3C 웹 저장소 API[ 리소스 13 ]를 지원해야 하며(MUST) HTML5/W3C IndexedDB API[ 리소스 14 ]를 지원해야 합니다(SHOULD). 웹 개발 표준 기관이 웹 저장소보다 IndexedDB를 선호하도록 전환함에 따라 IndexedDB는 Android의 향후 버전에서 필수 구성 요소가 될 것으로 예상됩니다.

모든 JavaScript API와 마찬가지로 HTML5 API는 개발자가 일반적인 Android API를 통해 명시적으로 활성화하지 않는 한 WebView에서 기본적으로 비활성화되어야 합니다.

3.4.2. 브라우저 호환성

기기 구현에는 일반 사용자 웹 탐색을 위한 독립형 브라우저 애플리케이션이 포함되어야 합니다(MUST). 독립형 브라우저는 WebKit 이외의 브라우저 기술을 기반으로 할 수도 있습니다. 그러나 대체 브라우저 애플리케이션을 사용하더라도 제3자 애플리케이션에 제공되는 android.webkit.WebView 구성 요소는 섹션 3.4.1에 설명된 대로 WebKit을 기반으로 해야 합니다.

구현은 독립형 브라우저 애플리케이션에 사용자 정의 사용자 에이전트 문자열을 제공할 수 있습니다.

독립형 브라우저 애플리케이션(업스트림 WebKit 브라우저 애플리케이션을 기반으로 하든 타사 대체 애플리케이션을 기반으로 하든)은 가능한 많은 HTML5 [ 리소스, 9 ]에 대한 지원을 포함해야 합니다. 최소한 기기 구현은 HTML5와 연결된 다음 API를 각각 지원해야 합니다(MUST).

• 애플리케이션 캐시/오프라인 작업 [ 리소스, 10 ]
• <video> 태그 [ 리소스, 11 ]
• 위치정보 [ 자료, 12 ]

또한 기기 구현은 HTML5/W3C 웹 저장소 API[ 리소스 13 ]를 지원해야 하며(MUST) HTML5/W3C IndexedDB API[ 리소스 14 ]를 지원해야 합니다(SHOULD). 웹 개발 표준 기관이 웹 저장소보다 IndexedDB를 선호하도록 전환함에 따라 IndexedDB는 Android의 향후 버전에서 필수 구성 요소가 될 것으로 예상됩니다.

3.5. API 동작 호환성

각 API 유형(관리형, 소프트, 네이티브 및 웹)의 동작은 업스트림 Android 오픈 소스 프로젝트[ 리소스, 3 ]의 기본 구현과 일치해야 합니다. 특정 호환성 영역은 다음과 같습니다.

• 장치는 표준 인텐트의 동작이나 의미를 변경해서는 안 됩니다.
• 장치는 특정 유형의 시스템 구성 요소(예: Service, Activity, ContentProvider 등)의 수명 주기 또는 수명 주기 의미를 변경해서는 안 됩니다.
• 장치는 표준 권한의 의미를 변경해서는 안 됩니다.

위 목록은 포괄적이지 않습니다. CTS(호환성 테스트 도구 모음)는 동작 호환성을 위해 플랫폼의 상당 부분을 테스트하지만 전부는 아닙니다. Android 오픈소스 프로젝트와의 동작 호환성을 보장하는 것은 구현자의 책임입니다. 이러한 이유로 기기 구현자는 시스템의 중요한 부분을 다시 구현하는 대신 가능한 경우 Android 오픈소스 프로젝트를 통해 제공되는 소스 코드를 사용해야 합니다.

3.6. API 네임스페이스

Android는 Java 프로그래밍 언어로 정의된 패키지 및 클래스 네임스페이스 규칙을 따릅니다. 타사 애플리케이션과의 호환성을 보장하기 위해 기기 구현자는 이러한 패키지 네임스페이스에 금지된 수정(아래 참조)을 해서는 안 됩니다.

• 자바.*
• javax.*
• 해.*
• 기계적 인조 인간.*
• com.android.*

금지된 수정은 다음과 같습니다:

• 기기 구현은 메서드나 클래스 서명을 변경하거나 클래스나 클래스 필드를 제거하여 Android 플랫폼에 공개적으로 노출된 API를 수정하면 안 됩니다(MUST NOT).
• 기기 구현자는 API의 기본 구현을 수정할 수 있지만 이러한 수정은 공개적으로 노출된 API의 명시된 동작 및 Java 언어 서명에 영향을 주어서는 안 됩니다.
• 기기 구현자는 공개적으로 노출된 요소(예: 클래스나 인터페이스, 기존 클래스나 인터페이스에 대한 필드나 메서드)를 위 API에 추가해서는 안 됩니다.

"공개적으로 노출된 요소"는 업스트림 Android 소스 코드에 사용된 "@hide" 마커로 장식되지 않은 모든 구성입니다. 즉, 기기 구현자는 위에 언급된 네임스페이스에서 새로운 API를 노출하거나 기존 API를 변경해서는 안 됩니다. 기기 구현자는 내부 전용 수정을 할 수 있지만 이러한 수정 사항을 개발자에게 알리거나 노출해서는 안 됩니다.

기기 구현자는 맞춤 API를 추가할 수 있지만 이러한 API는 다른 조직이 소유하거나 다른 조직을 참조하는 네임스페이스에 있어서는 안 됩니다. 예를 들어 기기 구현자는 com.google.* 또는 유사한 네임스페이스에 API를 추가하면 안 됩니다. 오직 Google만이 그렇게 할 수 있습니다. 마찬가지로 Google은 다른 회사의 네임스페이스에 API를 추가해서는 안 됩니다. 또한 기기 구현에 표준 Android 네임스페이스 외부의 맞춤 API가 포함되어 있는 경우 해당 API를 Android 공유 라이브러리에 패키징해야 합니다. 그래야 해당 API를 명시적으로 사용하는( <uses-library> 메커니즘을 통해) 앱만 증가된 메모리 사용량의 영향을 받을 수 있습니다. 이러한 API 중.

기기 구현자가 위의 패키지 네임스페이스 중 하나를 개선하도록 제안하는 경우(예: 기존 API에 유용한 새 기능을 추가하거나 새 API를 추가하는 등) 구현자는 source.android.com을 방문하여 변경 사항을 제공하고 해당 사이트의 정보에 따른 코드입니다.

위의 제한 사항은 Java 프로그래밍 언어의 API 이름 지정에 대한 표준 규칙에 해당합니다. 이 섹션의 목표는 단순히 이러한 규칙을 강화하고 이 호환성 정의에 포함하여 구속력을 갖도록 하는 것입니다.

3.7. 가상 머신 호환성

장치 구현은 전체 DEX(Dalvik Executable) 바이트코드 사양과 Dalvik 가상 머신 의미 체계를 지원해야 합니다[ 리소스, 15 ].

중간 밀도 또는 낮은 밀도로 분류된 화면을 사용하는 기기 구현은 각 애플리케이션에 최소 16MB의 메모리를 할당하도록 Dalvik을 구성해야 합니다(MUST). 고밀도 또는 초고밀도로 분류된 화면을 갖춘 기기 구현은 각 애플리케이션에 최소 24MB의 메모리를 할당하도록 Dalvik을 구성해야 합니다(MUST). 기기 구현은 이 수치보다 더 많은 메모리를 할당할 수 있습니다.

3.8. 사용자 인터페이스 호환성

Android 플랫폼에는 개발자가 시스템 사용자 인터페이스에 연결할 수 있는 일부 개발자 API가 포함되어 있습니다. 기기 구현은 아래에 설명된 대로 이러한 표준 UI API를 자신이 개발하는 맞춤 사용자 인터페이스에 통합해야 합니다.

3.8.1. 위젯

Android는 애플리케이션이 최종 사용자에게 "AppWidget"을 노출할 수 있도록 하는 구성 요소 유형과 해당 API 및 수명 주기를 정의합니다[ 리소스, 16 ]. Android 오픈 소스 참조 릴리스에는 사용자가 홈 화면에서 AppWidget을 추가하고, 보고, 제거할 수 있는 사용자 인터페이스 요소가 포함된 Launcher 애플리케이션이 포함되어 있습니다.

기기 구현자는 참조 런처(예: 홈 화면)를 대체할 수 있습니다. 대체 실행 프로그램은 AppWidget에 대한 기본 지원을 포함해야 하며 실행 프로그램 내에서 직접 AppWidget을 추가, 구성, 확인 및 제거할 수 있는 사용자 인터페이스 요소를 노출해야 합니다. 대체 실행 프로그램은 이러한 사용자 인터페이스 요소를 생략할 수 있습니다. 그러나 생략된 경우 기기 구현자는 사용자가 AppWidget을 추가, 구성, 보기, 제거할 수 있도록 런처에서 액세스할 수 있는 별도의 애플리케이션을 제공해야 합니다.

3.8.2. 알림

Android에는 개발자가 사용자에게 주목할만한 이벤트를 알릴 수 있는 API가 포함되어 있습니다[ 리소스, 17 ]. 장치 구현자는 이렇게 정의된 각 알림 클래스에 대한 지원을 제공해야 합니다. 구체적으로 말하면 소리, 진동, 조명 및 상태 표시줄입니다.

또한 구현 시 API[ 리소스, 18 ] 또는 상태 표시줄 아이콘 스타일 가이드[ 리소스, 19 ]에 제공된 모든 리소스(아이콘, 사운드 파일 등)를 올바르게 렌더링해야 합니다. 기기 구현자는 참조 Android 오픈소스 구현에서 제공하는 것보다 알림에 대한 대체 사용자 환경을 제공할 수 있습니다(MAY). 그러나 이러한 대체 알림 시스템은 위와 같이 기존 알림 리소스를 지원해야 합니다.

3.8.3. 찾다

Android에는 개발자가 검색을 애플리케이션에 통합하고 애플리케이션의 데이터를 전역 시스템 검색에 노출할 수 있는 API[ 리소스, 20 ]가 포함되어 있습니다. 일반적으로 이 기능은 사용자가 쿼리를 입력하고, 사용자가 입력할 때 제안 사항을 표시하고, 결과를 표시할 수 있는 시스템 전체의 단일 사용자 인터페이스로 구성됩니다. Android API를 사용하면 개발자는 이 인터페이스를 재사용하여 자신의 앱 내에서 검색을 제공하고 공통 글로벌 검색 사용자 인터페이스에 결과를 제공할 수 있습니다.

Device implementations MUST include a single, shared, system-wide search user interface capable of real-time suggestions in response to user input. Device implementations MUST implement the APIs that allow developers to reuse this user interface to provide search within their own applications. Device implementations MUST implement the APIs that allow third-party applications to add suggestions to the search box when it is run in global search mode. If no third-party applications are installed that make use of this functionality, the default behavior SHOULD be to display web search engine results and suggestions.

Device implementations MAY ship alternate search user interfaces, but SHOULD include a hard or soft dedicated search button, that can be used at any time within any app to invoke the search framework, with the behavior provided for in the API documentation.

3.8.4. Toasts

Applications can use the "Toast" API (defined in [ Resources, 21 ]) to display short non-modal strings to the end user, that disappear after a brief period of time. Device implementations MUST display Toasts from applications to end users in some high-visibility manner.

3.8.5. Live Wallpapers

Android defines a component type and corresponding API and lifecycle that allows applications to expose one or more "Live Wallpapers" to the end user [ Resources, 22 ]. Live Wallpapers are animations, patterns, or similar images with limited input capabilities that display as a wallpaper, behind other applications.

Hardware is considered capable of reliably running live wallpapers if it can run all live wallpapers, with no limitations on functionality, at a reasonable framerate with no adverse affects on other applications. If limitations in the hardware cause wallpapers and/or applications to crash, malfunction, consume excessive CPU or battery power, or run at unacceptably low frame rates, the hardware is considered incapable of running live wallpaper. As an example, some live wallpapers may use an Open GL 1.0 or 2.0 context to render their content. Live wallpaper will not run reliably on hardware that does not support multiple OpenGL contexts because the live wallpaper use of an OpenGL context may conflict with other applications that also use an OpenGL context.

Device implementations capable of running live wallpapers reliably as described above SHOULD implement live wallpapers. Device implementations determined to not run live wallpapers reliably as described above MUST NOT implement live wallpapers.

4. Application Packaging Compatibility

Device implementations MUST install and run Android ".apk" files as generated by the "aapt" tool included in the official Android SDK [ Resources, 23 ].

Devices implementations MUST NOT extend either the .apk [ Resources, 24 ], Android Manifest [ Resources, 25 ], or Dalvik bytecode [ Resources, 15 ] formats in such a way that would prevent those files from installing and running correctly on other compatible devices. Device implementers SHOULD use the reference upstream implementation of Dalvik, and the reference implementation's package management system.

5. Multimedia Compatibility

Device implementations MUST fully implement all multimedia APIs. Device implementations MUST include support for all multimedia codecs described below, and SHOULD meet the sound processing guidelines described below. Device implementations MUST include at least one form of audio output, such as speakers, headphone jack, external speaker connection, etc.

5.1. Media Codecs

Device implementations MUST support the multimedia codecs as detailed in the following sections. All of these codecs are provided as software implementations in the preferred Android implementation from the Android Open-Source Project.

Please note that neither Google nor the Open Handset Alliance make any representation that these codecs are unencumbered by third-party patents. Those intending to use this source code in hardware or software products are advised that implementations of this code, including in open source software or shareware, may require patent licenses from the relevant patent holders.

The tables below do not list specific bitrate requirements for most video codecs. The reason for this is that in practice, current device hardware does not necessarily support bitrates that map exactly to the required bitrates specified by the relevant standards. Instead, device implementations SHOULD support the highest bitrate practical on the hardware, up to the limits defined by the specifications.

5.1.1. Media Decoders

Device implementations MUST include an implementation of a decoder for each codec and format described in the table below. Note that decoders for each of these media types are provided by the upstream Android Open-Source Project.

5.1.2. Media Encoders

Device implementations SHOULD include encoders for as many of the media formats listed in Section 5.1.1. as possible. However, some encoders do not make sense for devices that lack certain optional hardware; for instance, an encoder for the H.263 video does not make sense, if the device lacks any cameras. Device implementations MUST therefore implement media encoders according to the conditions described in the table below.

See Section 7 for details on the conditions under which hardware may be omitted by device implementations.

In addition to the encoders listed above, device implementations SHOULD include an H.264 encoder. Note that the Compatibility Definition for a future version is planned to change this requirement to "MUST". That is, H.264 encoding is optional in Android 2.3 but will be required by a future version. Existing and new devices that run Android 2.3 are very strongly encouraged to meet this requirement in Android 2.3 , or they will not be able to attain Android compatibility when upgraded to the future version.

5.2. Audio Recording

When an application has used the android.media.AudioRecord API to start recording an audio stream, device implementations SHOULD sample and record audio with each of these behaviors:

• Noise reduction processing, if present, SHOULD be disabled.
• Automatic gain control, if present, SHOULD be disabled.
• The device SHOULD exhibit approximately flat amplitude versus frequency characteristics; specifically, ±3 dB, from 100 Hz to 4000 Hz
• Audio input sensitivity SHOULD be set such that a 90 dB sound power level (SPL) source at 1000 Hz yields RMS of 5000 for 16-bit samples.
• PCM amplitude levels SHOULD linearly track input SPL changes over at least a 30 dB range from -18 dB to +12 dB re 90 dB SPL at the microphone.
• Total harmonic distortion SHOULD be less than 1% from 100 Hz to 4000 Hz at 90 dB SPL input level.

Note: while the requirements outlined above are stated as "SHOULD" for Android 2.3, the Compatibility Definition for a future version is planned to change these to "MUST". That is, these requirements are optional in Android 2.3 but will be required by a future version. Existing and new devices that run Android 2.3 are very strongly encouraged to meet these requirements in Android 2.3 , or they will not be able to attain Android compatibility when upgraded to the future version.

5.3. Audio Latency

Audio latency is broadly defined as the interval between when an application requests an audio playback or record operation, and when the device implementation actually begins the operation. Many classes of applications rely on short latencies, to achieve real-time effects such sound effects or VOIP communication. Device implementations that include microphone hardware and declare android.hardware.microphone SHOULD meet all audio latency requirements outlined in this section. See Section 7 for details on the conditions under which microphone hardware may be omitted by device implementations.

For the purposes of this section:

• "cold output latency" is defined to be the interval between when an application requests audio playback and when sound begins playing, when the audio system has been idle and powered down prior to the request
• "warm output latency" is defined to be the interval between when an application requests audio playback and when sound begins playing, when the audio system has been recently used but is currently idle (that is, silent)
• "continuous output latency" is defined to be the interval between when an application issues a sample to be played and when the speaker physically plays the corresponding sound, while the device is currently playing back audio
• "cold input latency" is defined to be the interval between when an application requests audio recording and when the first sample is delivered to the application via its callback, when the audio system and microphone has been idle and powered down prior to the request
• "continuous input latency" is defined to be when an ambient sound occurs and when the sample corresponding to that sound is delivered to a recording application via its callback, while the device is in recording mode

Using the above definitions, device implementations SHOULD exhibit each of these properties:

• cold output latency of 100 milliseconds or less
• warm output latency of 10 milliseconds or less
• continuous output latency of 45 milliseconds or less
• cold input latency of 100 milliseconds or less
• continuous input latency of 50 milliseconds or less

Note: while the requirements outlined above are stated as "SHOULD" for Android 2.3, the Compatibility Definition for a future version is planned to change these to "MUST". That is, these requirements are optional in Android 2.3 but will be required by a future version. Existing and new devices that run Android 2.3 are very strongly encouraged to meet these requirements in Android 2.3 , or they will not be able to attain Android compatibility when upgraded to the future version.

If a device implementation meets the requirements of this section, it MAY report support for low-latency audio, by reporting the feature "android.hardware.audio.low-latency" via the android.content.pm.PackageManager class. [ Resources, 27 ] Conversely, if the device implementation does not meet these requirements it MUST NOT report support for low-latency audio.

6. Developer Tool Compatibility

Device implementations MUST support the Android Developer Tools provided in the Android SDK. Specifically, Android-compatible devices MUST be compatible with:

• Android Debug Bridge (known as adb) [ Resources, 23 ]
  Device implementations MUST support all adb functions as documented in the Android SDK. The device-side adb daemon SHOULD be inactive by default, but there MUST be a user-accessible mechanism to turn on the Android Debug Bridge.
• Dalvik Debug Monitor Service (known as ddms) [ Resources, 23 ]
  Device implementations MUST support all ddms features as documented in the Android SDK. As ddms uses adb , support for ddms SHOULD be inactive by default, but MUST be supported whenever the user has activated the Android Debug Bridge, as above.
• Monkey [ Resources, 26 ]
  Device implementations MUST include the Monkey framework, and make it available for applications to use.

Most Linux-based systems and Apple Macintosh systems recognize Android devices using the standard Android SDK tools, without additional support; however Microsoft Windows systems typically require a driver for new Android devices. (For instance, new vendor IDs and sometimes new device IDs require custom USB drivers for Windows systems.) If a device implementation is unrecognized by the adb tool as provided in the standard Android SDK, device implementers MUST provide Windows drivers allowing developers to connect to the device using the adb protocol. These drivers MUST be provided for Windows XP, Windows Vista, and Windows 7, in both 32-bit and 64-bit versions.

7. Hardware Compatibility

Android is intended to enable device implementers to create innovative form factors and configurations. At the same time Android developers write innovative applications that rely on the various hardware and features available through the Android APIs. The requirements in this section strike a balance between innovations available to device implementers, and the needs of developers to ensure their apps are only available to devices where they will run properly.

If a device includes a particular hardware component that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. If an API in the SDK interacts with a hardware component that is stated to be optional and the device implementation does not possess that component:

• complete class definitions (as documented by the SDK) for the component's APIs MUST still be present
• the API's behaviors MUST be implemented as no-ops in some reasonable fashion
• API methods MUST return null values where permitted by the SDK documentation
• API methods MUST return no-op implementations of classes where null values are not permitted by the SDK documentation
• API methods MUST NOT throw exceptions not documented by the SDK documentation

A typical example of a scenario where these requirements apply is the telephony API: even on non-phone devices, these APIs must be implemented as reasonable no-ops.

Device implementations MUST accurately report accurate hardware configuration information via the getSystemAvailableFeatures() and hasSystemFeature(String) methods on the android.content.pm.PackageManager class. [ Resources, 27 ]

7.1. Display and Graphics

Android 2.3 includes facilities that automatically adjust application assets and UI layouts appropriately for the device, to ensure that third-party applications run well on a variety of hardware configurations [ Resources, 28 ]. Devices MUST properly implement these APIs and behaviors, as detailed in this section.

7.1.1. Screen Configurations

Device implementations MAY use screens of any pixel dimensions, provided that they meet the following requirements:

• screens MUST be at least 2.5 inches in physical diagonal size
• density MUST be at least 100 dpi
• the aspect ratio MUST be between 1.333 (4:3) and 1.779 (16:9)
• the display technology used consists of square pixels

Device implementations with a screen meeting the requirements above are considered compatible, and no additional action is necessary. The Android framework implementation automatically computes display characteristics such as screen size bucket and density bucket. In the majority of cases, the framework decisions are the correct ones. If the default framework computations are used, no additional action is necessary. Device implementers wishing to change the defaults, or use a screen that does not meet the requirements above MUST contact the Android Compatibility Team for guidance, as provided for in Section 12.

The units used by the requirements above are defined as follows:

• "Physical diagonal size" is the distance in inches between two opposing corners of the illuminated portion of the display.
• "dpi" (meaning "dots per inch") is the number of pixels encompassed by a linear horizontal or vertical span of 1". Where dpi values are listed, both horizontal and vertical dpi must fall within the range.
• "Aspect ratio" is the ratio of the longer dimension of the screen to the shorter dimension. For example, a display of 480x854 pixels would be 854 / 480 = 1.779, or roughly "16:9".

Device implementations MUST use only displays with a single static configuration. That is, device implementations MUST NOT enable multiple screen configurations. For instance, since a typical television supports multiple resolutions such as 1080p, 720p, and so on, this configuration is not compatible with Android 2.3. (However, support for such configurations is under investigation and planned for a future version of Android.)

7.1.2. Display Metrics

Device implementations MUST report correct values for all display metrics defined in android.util.DisplayMetrics [ Resources, 29 ].

7.1.3. Declared Screen Support

Applications optionally indicate which screen sizes they support via the <supports-screens> attribute in the AndroidManifest.xml file. Device implementations MUST correctly honor applications' stated support for small, medium, and large screens, as described in the Android SDK documentation.

7.1.4. Screen Orientation

Compatible devices MUST support dynamic orientation by applications to either portrait or landscape screen orientation. That is, the device must respect the application's request for a specific screen orientation. Device implementations MAY select either portrait or landscape orientation as the default. Devices that cannot be physically rotated MAY meet this requirement by "letterboxing" applications that request portrait mode, using only a portion of the available display.

Devices MUST report the correct value for the device's current orientation, whenever queried via the android.content.res.Configuration.orientation, android.view.Display.getOrientation(), or other APIs.

7.1.5. 3D Graphics Acceleration

Device implementations MUST support OpenGL ES 1.0, as required by the Android 2.3 APIs. For devices that lack 3D acceleration hardware, a software implementation of OpenGL ES 1.0 is provided by the upstream Android Open-Source Project. Device implementations SHOULD support OpenGL ES 2.0.

Implementations MAY omit Open GL ES 2.0 support; however if support is omitted, device implementations MUST NOT report as supporting OpenGL ES 2.0. Specifically, if a device implementations lacks OpenGL ES 2.0 support:

• the managed APIs (such as via the GLES10.getString() method) MUST NOT report support for OpenGL ES 2.0
• the native C/C++ OpenGL APIs (that is, those available to apps via libGLES_v1CM.so, libGLES_v2.so, or libEGL.so) MUST NOT report support for OpenGL ES 2.0.

Conversely, if a device implementation does support OpenGL ES 2.0, it MUST accurately report that support via the routes just listed.

Note that Android 2.3 includes support for applications to optionally specify that they require specific OpenGL texture compression formats. These formats are typically vendor-specific. Device implementations are not required by Android 2.3 to implement any specific texture compression format. However, they SHOULD accurately report any texture compression formats that they do support, via the getString() method in the OpenGL API.

7.2. Input Devices

Android 2.3 supports a number of modalities for user input. Device implementations MUST support user input devices as provided for in this section.

7.2.1. Keyboard

Device implementations:

• MUST include support for the Input Management Framework (which allows third party developers to create Input Management Engines -- ie soft keyboard) as detailed at developer.android.com
• MUST provide at least one soft keyboard implementation (regardless of whether a hard keyboard is present)
• MAY include additional soft keyboard implementations
• MAY include a hardware keyboard
• MUST NOT include a hardware keyboard that does not match one of the formats specified in android.content.res.Configuration.keyboard [ Resources, 30 ] (that is, QWERTY, or 12-key)

7.2.2. Non-touch Navigation

Device implementations:

• MAY omit a non-touch navigation option (that is, may omit a trackball, d-pad, or wheel)
• MUST report the correct value for android.content.res.Configuration.navigation [ Resources, 30 ]
• MUST provide a reasonable alternative user interface mechanism for the selection and editing of text, compatible with Input Management Engines. The upstream Android Open-Source code includes a selection mechanism suitable for use with devices that lack non-touch navigation inputs.

7.2.3. Navigation keys

The Home, Menu and Back functions are essential to the Android navigation paradigm. Device implementations MUST make these functions available to the user at all times, regardless of application state. These functions SHOULD be implemented via dedicated buttons. They MAY be implemented using software, gestures, touch panel, etc., but if so they MUST be always accessible and not obscure or interfere with the available application display area.

Device implementers SHOULD also provide a dedicated search key. Device implementers MAY also provide send and end keys for phone calls.

7.2.4. Touchscreen input

Device implementations:

• MUST have a touchscreen
• MAY have either capacitive or resistive touchscreen
• MUST report the value of android.content.res.Configuration [ Resources, 30 ] reflecting corresponding to the type of the specific touchscreen on the device
• SHOULD support fully independently tracked pointers, if the touchscreen supports multiple pointers

7.3. Sensors

Android 2.3 includes APIs for accessing a variety of sensor types. Devices implementations generally MAY omit these sensors, as provided for in the following subsections. If a device includes a particular sensor type that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. For example, device implementations:

• MUST accurately report the presence or absence of sensors per the android.content.pm.PackageManager class. [ Resources, 27 ]
• MUST return an accurate list of supported sensors via the SensorManager.getSensorList() and similar methods
• MUST behave reasonably for all other sensor APIs (for example, by returning true or false as appropriate when applications attempt to register listeners, not calling sensor listeners when the corresponding sensors are not present; etc.)

The list above is not comprehensive; the documented behavior of the Android SDK is to be considered authoritative.

Some sensor types are synthetic, meaning they can be derived from data provided by one or more other sensors. (Examples include the orientation sensor, and the linear acceleration sensor.) Device implementations SHOULD implement these sensor types, when they include the prerequisite physical sensors.

The Android 2.3 APIs introduce a notion of a "streaming" sensor, which is one that returns data continuously, rather than only when the data changes. Device implementations MUST continuously provide periodic data samples for any API indicated by the Android 2.3 SDK documentation to be a streaming sensor.

7.3.1. Accelerometer

Device implementations SHOULD include a 3-axis accelerometer. If a device implementation does include a 3-axis accelerometer, it:

• MUST be able to deliver events at 50 Hz or greater
• MUST comply with the Android sensor coordinate system as detailed in the Android APIs (see [ Resources, 31 ])
• MUST be capable of measuring from freefall up to twice gravity (2g) or more on any three-dimensional vector
• MUST have 8-bits of accuracy or more
• MUST have a standard deviation no greater than 0.05 m/s^2

7.3.2. Magnetometer

Device implementations SHOULD include a 3-axis magnetometer (ie compass.) If a device does include a 3-axis magnetometer, it:

• MUST be able to deliver events at 10 Hz or greater
• MUST comply with the Android sensor coordinate system as detailed in the Android APIs (see [ Resources, 31 ]).
• MUST be capable of sampling a range of field strengths adequate to cover the geomagnetic field
• MUST have 8-bits of accuracy or more
• MUST have a standard deviation no greater than 0.5 µT

7.3.3. GPS

Device implementations SHOULD include a GPS receiver. If a device implementation does include a GPS receiver, it SHOULD include some form of "assisted GPS" technique to minimize GPS lock-on time.

7.3.4. Gyroscope

Device implementations SHOULD include a gyroscope (ie angular change sensor.) Devices SHOULD NOT include a gyroscope sensor unless a 3-axis accelerometer is also included. If a device implementation includes a gyroscope, it:

• MUST be capable of measuring orientation changes up to 5.5*Pi radians/second (that is, approximately 1,000 degrees per second)
• MUST be able to deliver events at 100 Hz or greater
• MUST have 8-bits of accuracy or more

7.3.5. Barometer

Device implementations MAY include a barometer (ie ambient air pressure sensor.) If a device implementation includes a barometer, it:

• MUST be able to deliver events at 5 Hz or greater
• MUST have adequate precision to enable estimating altitude

7.3.7. Thermometer

Device implementations MAY but SHOULD NOT include a thermometer (ie temperature sensor.) If a device implementation does include a thermometer, it MUST measure the temperature of the device CPU. It MUST NOT measure any other temperature. (Note that this sensor type is deprecated in the Android 2.3 APIs.)

7.3.7. Photometer

Device implementations MAY include a photometer (ie ambient light sensor.)

7.3.8. Proximity Sensor

Device implementations MAY include a proximity sensor. If a device implementation does include a proximity sensor, it MUST measure the proximity of an object in the same direction as the screen. That is, the proximity sensor MUST be oriented to detect objects close to the screen, as the primary intent of this sensor type is to detect a phone in use by the user. If a device implementation includes a proximity sensor with any other orientation, it MUST NOT be accessible through this API. If a device implementation has a proximity sensor, it MUST be have 1-bit of accuracy or more.

7.4. Data Connectivity

Network connectivity and access to the Internet are vital features of Android. Meanwhile, device-to-device interaction adds significant value to Android devices and applications. Device implementations MUST meet the data connectivity requirements in this section.

7.4.1. Telephony

"Telephony" as used by the Android 2.3 APIs and this document refers specifically to hardware related to placing voice calls and sending SMS messages via a GSM or CDMA network. While these voice calls may or may not be packet-switched, they are for the purposes of Android 2.3 considered independent of any data connectivity that may be implemented using the same network. In other words, the Android "telephony" functionality and APIs refer specifically to voice calls and SMS; for instance, device implementations that cannot place calls or send/receive SMS messages MUST NOT report the "android.hardware.telephony" feature or any sub-features, regardless of whether they use a cellular network for data connectivity.

Android 2.3 MAY be used on devices that do not include telephony hardware. That is, Android 2.3 is compatible with devices that are not phones. However, if a device implementation does include GSM or CDMA telephony, it MUST implement full support for the API for that technology. Device implementations that do not include telephony hardware MUST implement the full APIs as no-ops.

7.4.2. IEEE 802.11 (WiFi)

Android 2.3 device implementations SHOULD include support for one or more forms of 802.11 (b/g/a/n, etc.) If a device implementation does include support for 802.11, it MUST implement the corresponding Android API.

7.4.3. Bluetooth

Device implementations SHOULD include a Bluetooth transceiver. Device implementations that do include a Bluetooth transceiver MUST enable the RFCOMM-based Bluetooth API as described in the SDK documentation [ Resources, 32 ]. Device implementations SHOULD implement relevant Bluetooth profiles, such as A2DP, AVRCP, OBEX, etc. as appropriate for the device.

The Compatibility Test Suite includes cases that cover basic operation of the Android RFCOMM Bluetooth API. However, since Bluetooth is a communications protocol between devices, it cannot be fully tested by unit tests running on a single device. Consequently, device implementations MUST also pass the human-driven Bluetooth test procedure described in Appendix A.

7.4.4. Near-Field Communications

Device implementations SHOULD include a transceiver and related hardware for Near-Field Communications (NFC). If a device implementation does include NFC hardware, then it:

• MUST report the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method. [ Resources, 27 ]
• MUST be capable of reading and writing NDEF messages via the following NFC standards:
  • MUST be capable of acting as an NFC Forum reader/writer (as defined by the NFC Forum technical specification NFCForum-TS-DigitalProtocol-1.0) via the following NFC standards:
    • NfcA (ISO14443-3A)
    • NfcB (ISO14443-3B)
    • NfcF (JIS 6319-4)
    • NfcV (ISO 15693)
    • IsoDep (ISO 14443-4)
    • NFC Forum Tag Types 1, 2, 3, 4 (defined by the NFC Forum)
  • MUST be capable of transmitting and receiving data via the following peer-to-peer standards and protocols:
    • ISO 18092
    • LLCP 1.0 (defined by the NFC Forum)
    • SDP 1.0 (defined by the NFC Forum)
    • NDEF Push Protocol [ Resources, 33 ]
  • MUST scan for all supported technologies while in NFC discovery mode.
  • SHOULD be in NFC discovery mode while the device is awake with the screen active.

  (Note that publicly available links are not available for the JIS, ISO, and NFC Forum specifications cited above.)

  Additionally, device implementations SHOULD support the following widely-deployed MIFARE technologies.

  • MIFARE Classic (NXP MF1S503x [ Resources, 34 ], MF1S703x [ Resources, 35 ])
  • MIFARE Ultralight (NXP MF0ICU1 [ Resources, 36 ], MF0ICU2 [ Resources, 37 ])
  • NDEF on MIFARE Classic (NXP AN130511 [ Resources, 38 ], AN130411 [ Resources, 39 ])

  Note that Android 2.3.3 includes APIs for these MIFARE types. If a device implementation supports MIFARE, it:

  • MUST implement the corresponding Android APIs as documented by the Android SDK
  • MUST report the feature com.nxp.mifare from the android.content.pm.PackageManager.hasSystemFeature() method. [ Resources, 27 ] Note that this is not a standard Android feature, and as such does not appear as a constant on the PackageManager class.
  • MUST NOT implement the corresponding Android APIs nor report the com.nxp.mifare feature unless it also implements general NFC support as described in this section

  If a device implementation does not include NFC hardware, it MUST NOT declare the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method [ Resources, 27 ], and MUST implement the Android 2.3 NFC API as a no-op.

  As the classes android.nfc.NdefMessage and android.nfc.NdefRecord represent a protocol-independent data representation format, device implementations MUST implement these APIs even if they do not include support for NFC or declare the android.hardware.nfc feature.

  7.4.5. Minimum Network Capability

  Device implementations MUST include support for one or more forms of data networking. Specifically, device implementations MUST include support for at least one data standard capable of 200Kbit/sec or greater. Examples of technologies that satisfy this requirement include EDGE, HSPA, EV-DO, 802.11g, Ethernet, etc.

  Device implementations where a physical networking standard (such as Ethernet) is the primary data connection SHOULD also include support for at least one common wireless data standard, such as 802.11 (WiFi).

  Devices MAY implement more than one form of data connectivity.

  7.5. Cameras

  Device implementations SHOULD include a rear-facing camera, and MAY include a front-facing camera. A rear-facing camera is a camera located on the side of the device opposite the display; that is, it images scenes on the far side of the device, like a traditional camera. A front-facing camera is a camera located on the same side of the device as the display; that is, a camera typically used to image the user, such as for video conferencing and similar applications.

  7.5.1. Rear-Facing Camera

  Device implementations SHOULD include a rear-facing camera. If a device implementation includes a rear-facing camera, it:

  • MUST have a resolution of at least 2 megapixels
  • SHOULD have either hardware auto-focus, or software auto-focus implemented in the camera driver (transparent to application software)
  • MAY have fixed-focus or EDOF (extended depth of field) hardware
  • MAY include a flash. If the Camera includes a flash, the flash lamp MUST NOT be lit while an android.hardware.Camera.PreviewCallback instance has been registered on a Camera preview surface, unless the application has explicitly enabled the flash by enabling the FLASH_MODE_AUTO or FLASH_MODE_ON attributes of a Camera.Parameters object. Note that this constraint does not apply to the device's built-in system camera application, but only to third-party applications using Camera.PreviewCallback .

  7.5.2. Front-Facing Camera

  Device implementations MAY include a front-facing camera. If a device implementation includes a front-facing camera, it:

  • MUST have a resolution of at least VGA (that is, 640x480 pixels)
  • MUST NOT use a front-facing camera as the default for the Camera API. That is, the camera API in Android 2.3 has specific support for front-facing cameras, and device implementations MUST NOT configure the API to to treat a front-facing camera as the default rear-facing camera, even if it is the only camera on the device.
  • MAY include features (such as auto-focus, flash, etc.) available to rear-facing cameras as described in Section 7.5.1.
  • MUST horizontally reflect (ie mirror) the stream displayed by an app in a CameraPreview, as follows:
  • If the device implementation is capable of being rotated by user (such as automatically via an accelerometer or manually via user input), the camera preview MUST be mirrored horizontally relative to the device's current orientation.
  • If the current application has explicitly requested that the Camera display be rotated via a call to the android.hardware.Camera.setDisplayOrientation() [ Resources, 40 ] method, the camera preview MUST be mirrored horizontally relative to the orientation specified by the application.
  • Otherwise, the preview MUST be mirrored along the device's default horizontal axis.
  • MUST mirror the image data returned to any "postview" camera callback handlers, in the same manner as the camera preview image stream. (If the device implementation does not support postview callbacks, this requirement obviously does not apply.)
  • MUST NOT mirror the final captured still image or video streams returned to application callbacks or committed to media storage

  7.5.3. Camera API Behavior

  Device implementations MUST implement the following behaviors for the camera-related APIs, for both front- and rear-facing cameras:

  1. If an application has never called android.hardware.Camera.Parameters.setPreviewFormat(int), then the device MUST use android.hardware.PixelFormat.YCbCr_420_SP for preview data provided to application callbacks.
  2. If an application registers an android.hardware.Camera.PreviewCallback instance and the system calls the onPreviewFrame() method when the preview format is YCbCr_420_SP, the data in the byte[] passed into onPreviewFrame() must further be in the NV21 encoding format. That is, NV21 MUST be the default.
  3. Device implementations SHOULD support the YV12 format (as denoted by the android.graphics.ImageFormat.YV12 constant) for camera previews for both front- and rear-facing cameras. Note that the Compatibility Definition for a future version is planned to change this requirement to "MUST". That is, YV12 support is optional in Android 2.3 but will be required by a future version. Existing and new devices that run Android 2.3 are very strongly encouraged to meet this requirement in Android 2.3 , or they will not be able to attain Android compatibility when upgraded to the future version.

  Device implementations MUST implement the full Camera API included in the Android 2.3 SDK documentation [ Resources, 41 ]), regardless of whether the device includes hardware autofocus or other capabilities. For instance, cameras that lack autofocus MUST still call any registered android.hardware.Camera.AutoFocusCallback instances (even though this has no relevance to a non-autofocus camera.) Note that this does apply to front-facing cameras; for instance, even though most front-facing cameras do not support autofocus, the API callbacks must still be "faked" as described.

  Device implementations MUST recognize and honor each parameter name defined as a constant on the android.hardware.Camera.Parameters class, if the underlying hardware supports the feature. If the device hardware does not support a feature, the API must behave as documented. Conversely, Device implementations MUST NOT honor or recognize string constants passed to the android.hardware.Camera.setParameters() method other than those documented as constants on the android.hardware.Camera.Parameters . That is, device implementations MUST support all standard Camera parameters if the hardware allows, and MUST NOT support custom Camera parameter types.

  7.5.4. Camera Orientation

  Both front- and rear-facing cameras, if present, MUST be oriented so that the long dimension of the camera aligns with the screen's long dimension. That is, when the device is held in the landscape orientation, a cameras MUST capture images in the landscape orientation. This applies regardless of the device's natural orientation; that is, it applies to landscape-primary devices as well as portrait-primary devices.

  7.6. Memory and Storage

  The fundamental function of Android 2.3 is to run applications. Device implementations MUST the requirements of this section, to ensure adequate storage and memory for applications to run properly.

  7.6.1. Minimum Memory and Storage

  Device implementations MUST have at least 128MB of memory available to the kernel and userspace. The 128MB MUST be in addition to any memory dedicated to hardware components such as radio, memory, and so on that is not under the kernel's control.

  Device implementations MUST have at least 150MB of non-volatile storage available for user data. That is, the /data partition MUST be at least 150MB.

  Beyond the requirements above, device implementations SHOULD have at least 1GB of non-volatile storage available for user data. Note that this higher requirement is planned to become a hard minimum in a future version of Android. Device implementations are strongly encouraged to meet these requirements now, or else they may not be eligible for compatibility for a future version of Android.

  The Android APIs include a Download Manager that applications may use to download data files. The Download Manager implementation MUST be capable of downloading individual files 55MB in size, or larger. The Download Manager implementation SHOULD be capable of downloading files 100MB in size, or larger.

  7.6.2. Application Shared Storage

  Device implementations MUST offer shared storage for applications. The shared storage provided MUST be at least 1GB in size.

  Device implementations MUST be configured with shared storage mounted by default, "out of the box". If the shared storage is not mounted on the Linux path /sdcard , then the device MUST include a Linux symbolic link from /sdcard to the actual mount point.

  Device implementations MUST enforce as documented the android.permission.WRITE_EXTERNAL_STORAGE permission on this shared storage. Shared storage MUST otherwise be writable by any application that obtains that permission.

  Device implementations MAY have hardware for user-accessible removable storage, such as a Secure Digital card. Alternatively, device implementations MAY allocate internal (non-removable) storage as shared storage for apps.

  Regardless of the form of shared storage used, device implementations MUST provide some mechanism to access the contents of shared storage from a host computer, such as USB mass storage or Media Transfer Protocol.

  It is illustrative to consider two common examples. If a device implementation includes an SD card slot to satisfy the shared storage requirement, a FAT-formatted SD card 1GB in size or larger MUST be included with the device as sold to users, and MUST be mounted by default. Alternatively, if a device implementation uses internal fixed storage to satisfy this requirement, that storage MUST be 1GB in size or larger and mounted on /sdcard (or /sdcard MUST be a symbolic link to the physical location if it is mounted elsewhere.)

  Device implementations that include multiple shared storage paths (such as both an SD card slot and shared internal storage) SHOULD modify the core applications such as the media scanner and ContentProvider to transparently support files placed in both locations.

  7.7. USB

  Device implementations:

  • MUST implement a USB client, connectable to a USB host with a standard USB-A port
  • MUST implement the Android Debug Bridge over USB (as described in Section 7)
  • MUST implement the USB mass storage specification, to allow a host connected to the device to access the contents of the /sdcard volume
  • SHOULD use the micro USB form factor on the device side
  • MAY include a non-standard port on the device side, but if so MUST ship with a cable capable of connecting the custom pinout to standard USB-A port

  8. Performance Compatibility

  Compatible implementations must ensure not only that applications simply run correctly on the device, but that they do so with reasonable performance and overall good user experience. Device implementations MUST meet the key performance metrics of an Android 2.3 compatible device defined in the table below:

  Metric	Performance Threshold	Comments
  Application Launch Time	The following applications should launch within the specified time. Browser: less than 1300ms MMS/SMS: less than 700ms AlarmClock: less than 650ms	The launch time is measured as the total time to complete loading the default activity for the application, including the time it takes to start the Linux process, load the Android package into the Dalvik VM, and call onCreate.
  Simultaneous Applications	When multiple applications have been launched, re-launching an already-running application after it has been launched must take less than the original launch time.

  9. Security Model Compatibility

  Device implementations MUST implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs [ Resources, 42 ] in the Android developer documentation. Device implementations MUST support installation of self-signed applications without requiring any additional permissions/certificates from any third parties/authorities. Specifically, compatible devices MUST support the security mechanisms described in the follow sub-sections.

  9.1. Permissions

  Device implementations MUST support the Android permissions model as defined in the Android developer documentation [ Resources, 42 ]. Specifically, implementations MUST enforce each permission defined as described in the SDK documentation; no permissions may be omitted, altered, or ignored. Implementations MAY add additional permissions, provided the new permission ID strings are not in the android.* namespace.

  9.2. UID and Process Isolation

  Device implementations MUST support the Android application sandbox model, in which each application runs as a unique Unix-style UID and in a separate process. Device implementations MUST support running multiple applications as the same Linux user ID, provided that the applications are properly signed and constructed, as defined in the Security and Permissions reference [ Resources, 42 ].

  9.3. Filesystem Permissions

  Device implementations MUST support the Android file access permissions model as defined in as defined in the Security and Permissions reference [ Resources, 42 ].

  9.4. Alternate Execution Environments

  Device implementations MAY include runtime environments that execute applications using some other software or technology than the Dalvik virtual machine or native code. However, such alternate execution environments MUST NOT compromise the Android security model or the security of installed Android applications, as described in this section.

  Alternate runtimes MUST themselves be Android applications, and abide by the standard Android security model, as described elsewhere in Section 9.

  Alternate runtimes MUST NOT be granted access to resources protected by permissions not requested in the runtime's AndroidManifest.xml file via the <uses-permission> mechanism.

  Alternate runtimes MUST NOT permit applications to make use of features protected by Android permissions restricted to system applications.

  Alternate runtimes MUST abide by the Android sandbox model. Specifically:

  • Alternate runtimes SHOULD install apps via the PackageManager into separate Android sandboxes (that is, Linux user IDs, etc.)
  • Alternate runtimes MAY provide a single Android sandbox shared by all applications using the alternate runtime.
  • Alternate runtimes and installed applications using an alternate runtime MUST NOT reuse the sandbox of any other app installed on the device, except through the standard Android mechanisms of shared user ID and signing certificate
  • Alternate runtimes MUST NOT launch with, grant, or be granted access to the sandboxes corresponding to other Android applications.

  Alternate runtimes MUST NOT be launched with, be granted, or grant to other applications any privileges of the superuser (root), or of any other user ID.

  The .apk files of alternate runtimes MAY be included in the system image of a device implementation, but MUST be signed with a key distinct from the key used to sign other applications included with the device implementation.

  When installing applications, alternate runtimes MUST obtain user consent for the Android permissions used by the application. That is, if an application needs to make use of a device resource for which there is a corresponding Android permission (such as Camera, GPS, etc.), the alternate runtime MUST inform the user that the application will be able to access that resource. If the runtime environment does not record application capabilities in this manner, the runtime environment MUST list all permissions held by the runtime itself when installing any application using that runtime.

  10. Software Compatibility Testing

  The Android Open-Source Project includes various testing tools to verify that device implementations are compatible. Device implementations MUST pass all tests described in this section.

  However, note that no software test package is fully comprehensive. For this reason, device implementers are very strongly encouraged to make the minimum number of changes as possible to the reference and preferred implementation of Android 2.3 available from the Android Open-Source Project. This will minimize the risk of introducing bugs that create incompatibilities requiring rework and potential device updates.

  10.1. Compatibility Test Suite

  Device implementations MUST pass the Android Compatibility Test Suite (CTS) [ Resources, 2 ] available from the Android Open Source Project, using the final shipping software on the device. Additionally, device implementers SHOULD use the reference implementation in the Android Open Source tree as much as possible, and MUST ensure compatibility in cases of ambiguity in CTS and for any reimplementations of parts of the reference source code.

  The CTS is designed to be run on an actual device. Like any software, the CTS may itself contain bugs. The CTS will be versioned independently of this Compatibility Definition, and multiple revisions of the CTS may be released for Android 2.3. Device implementations MUST pass the latest CTS version available at the time the device software is completed.

  MUST pass the most recent version of the Android Compatibility Test Suite (CTS) available at the time of the device implementation's software is completed. (The CTS is available as part of the Android Open Source Project [ Resources, 2 ].) The CTS tests many, but not all, of the components outlined in this document.

  10.2. CTS Verifier

  Device implementations MUST correctly execute all applicable cases in the CTS Verifier. The CTS Verifier is included with the Compatibility Test Suite, and is intended to be run by a human operator to test functionality that cannot be tested by an automated system, such as correct functioning of a camera and sensors.

  The CTS Verifier has tests for many kinds of hardware, including some hardware that is optional. Device implementations MUST pass all tests for hardware which they possess; for instance, if a device possesses an accelerometer, it MUST correctly execute the Accelerometer test case in the CTS Verifier. Test cases for features noted as optional by this Compatibility Definition Document MAY be skipped or omitted.

  Every device and every build MUST correctly run the CTS Verifier, as noted above. However, since many builds are very similar, device implementers are not expected to explicitly run the CTS Verifier on builds that differ only in trivial ways. Specifically, device implementations that differ from an implementation that has passed the CTS Verfier only by the set of included locales, branding, etc. MAY omit the CTS Verifier test.

  10.3. Reference Applications

  Device implementers MUST test implementation compatibility using the following open-source applications:

  • The "Apps for Android" applications [ Resources, 43 ].
  • Replica Island (available in Android Market; only required for device implementations that support with OpenGL ES 2.0)

  Each app above MUST launch and behave correctly on the implementation, for the implementation to be considered compatible.

  11. Updatable Software

  Device implementations MUST include a mechanism to replace the entirety of the system software. The mechanism need not perform "live" upgrades -- that is, a device restart MAY be required.

  Any method can be used, provided that it can replace the entirety of the software preinstalled on the device. For instance, any of the following approaches will satisfy this requirement:

  • Over-the-air (OTA) downloads with offline update via reboot
  • "Tethered" updates over USB from a host PC
  • "Offline" updates via a reboot and update from a file on removable storage

  The update mechanism used MUST support updates without wiping user data. Note that the upstream Android software includes an update mechanism that satisfies this requirement.

  If an error is found in a device implementation after it has been released but within its reasonable product lifetime that is determined in consultation with the Android Compatibility Team to affect the compatibility of third-party applications, the device implementer MUST correct the error via a software update available that can be applied per the mechanism just described.

  12. Contact Us

  You can contact the document authors at compatibility@android.com for clarifications and to bring up any issues that you think the document does not cover.

  Appendix A - Bluetooth Test Procedure

  The Compatibility Test Suite includes cases that cover basic operation of the Android RFCOMM Bluetooth API. However, since Bluetooth is a communications protocol between devices, it cannot be fully tested by unit tests running on a single device. Consequently, device implementations MUST also pass the human-operated Bluetooth test procedure described below.

  The test procedure is based on the BluetoothChat sample app included in the Android open-source project tree. The procedure requires two devices:

  • a candidate device implementation running the software build to be tested
  • a separate device implementation already known to be compatible, and of a model from the device implementation being tested -- that is, a "known good" device implementation

  The test procedure below refers to these devices as the "candidate" and "known good" devices, respectively.

  Setup and Installation

  1. Build BluetoothChat.apk via 'make samples' from an Android source code tree.
  2. Install BluetoothChat.apk on the known-good device.
  3. Install BluetoothChat.apk on the candidate device.

  Test Bluetooth Control by Apps

  1. Launch BluetoothChat on the candidate device, while Bluetooth is disabled.
  2. Verify that the candidate device either turns on Bluetooth, or prompts the user with a dialog to turn on Bluetooth.

  Test Pairing and Communication

  1. Launch the Bluetooth Chat app on both devices.
  2. Make the known-good device discoverable from within BluetoothChat (using the Menu).
  3. On the candidate device, scan for Bluetooth devices from within BluetoothChat (using the Menu) and pair with the known-good device.
  4. Send 10 or more messages from each device, and verify that the other device receives them correctly.
  5. Close the BluetoothChat app on both devices by pressing Home .
  6. Unpair each device from the other, using the device Settings app.

  Test Pairing and Communication in the Reverse Direction

  1. Launch the Bluetooth Chat app on both devices.
  2. Make the candidate device discoverable from within BluetoothChat (using the Menu).
  3. On the known-good device, scan for Bluetooth devices from within BluetoothChat (using the Menu) and pair with the candidate device.
  4. Send 10 or messages from each device, and verify that the other device receives them correctly.
  5. Close the Bluetooth Chat app on both devices by pressing Back repeatedly to get to the Launcher.

  Test Re-Launches

  1. Re-launch the Bluetooth Chat app on both devices.
  2. Send 10 or messages from each device, and verify that the other device receives them correctly.

  Note: the above tests have some cases which end a test section by using Home, and some using Back. These tests are not redundant and are not optional: the objective is to verify that the Bluetooth API and stack works correctly both when Activities are explicitly terminated (via the user pressing Back, which calls finish()), and implicitly sent to background (via the user pressing Home.) Each test sequence MUST be performed as described.