3.2. Soft API Compatibility

In addition to the managed APIs from section 3.1, Android also includes a significant runtime-only “soft” API, in the form of such things as intents, permissions, and similar aspects of Android applications that cannot be enforced at application compile time.

3.2.1. Permissions

• [C-0-1] Device implementers MUST support and enforce all permission constants as documented by the Permission reference page. Note that section 9 lists additional requirements related to the Android security model.

3.2.2. Build Parameters

The Android APIs include a number of constants on the android.os.Build class that are intended to describe the current device.

• [C-0-1] To provide consistent, meaningful values across device implementations, the table below includes additional restrictions on the formats of these values to which device implementations MUST conform.

3.2.3. Intent Compatibility

3.2.3.1. Core Application Intents

Android intents allow application components to request functionality from other Android components. The Android upstream project includes a list of applications considered core Android applications, which implements several intent patterns to perform common actions.

• [C-0-1] Device implementations MUST preload one or more applications or service components with an intent handler, for all the public intent filter patterns defined by the following core android applications in AOSP:

  • Desk Clock
  • Browser
  • Calendar
  • Contacts
  • Gallery
  • GlobalSearch
  • Launcher
  • Music
  • Settings

3.2.3.2. Intent Resolution

• [C-0-1] As Android is an extensible platform, device implementations MUST allow each intent pattern referenced in section 3.2.3.1 , except for Settings, to be overridden by third-party applications. The upstream Android open source implementation allows this by default.

• [C-0-2] Dvice implementers MUST NOT attach special privileges to system applications' use of these intent patterns, or prevent third-party applications from binding to and assuming control of these patterns. This prohibition specifically includes but is not limited to disabling the “Chooser” user interface that allows the user to select between multiple applications that all handle the same intent pattern.

• [C-0-3] Device implementations MUST provide a user interface for users to modify the default activity for intents.

• However, device implementations MAY provide default activities for specific URI patterns (e.g. http://play.google.com) when the default activity provides a more specific attribute for the data URI. For example, an intent filter pattern specifying the data URI “http://www.android.com” is more specific than the browser's core intent pattern for “http://”.

Android also includes a mechanism for third-party apps to declare an authoritative default app linking behavior for certain types of web URI intents. When such authoritative declarations are defined in an app's intent filter patterns, device implementations:

• [C-0-4] MUST attempt to validate any intent filters by performing the validation steps defined in the Digital Asset Links specification as implemented by the Package Manager in the upstream Android Open Source Project.
• [C-0-5] MUST attempt validation of the intent filters during the installation of the application and set all successfully validated URI intent filters as default app handlers for their URIs.
• MAY set specific URI intent filters as default app handlers for their URIs, if they are successfully verified but other candidate URI filters fail verification. If a device implementation does this, it MUST provide the user appropriate per-URI pattern overrides in the settings menu.
• MUST provide the user with per-app App Links controls in Settings as follows:
  • [C-0-6] The user MUST be able to override holistically the default app links behavior for an app to be: always open, always ask, or never open, which must apply to all candidate URI intent filters equally.
  • [C-0-7] The user MUST be able to see a list of the candidate URI intent filters.
  • The device implementation MAY provide the user with the ability to override specific candidate URI intent filters that were successfully verified, on a per-intent filter basis.
  • [C-0-8] The device implementation MUST provide users with the ability to view and override specific candidate URI intent filters if the device implementation lets some candidate URI intent filters succeed verification while some others can fail.

3.2.3.3. Intent Namespaces

• [C-0-1] Device implementations MUST NOT include any Android component that honors any new intent or broadcast intent patterns using an ACTION, CATEGORY, or other key string in the android.* or com.android.* namespace.
• [C-0-2] Device implementers MUST NOT include any Android components that honor any new intent or broadcast intent patterns using an ACTION, CATEGORY, or other key string in a package space belonging to another organization.
• [C-0-3] Device implementers MUST NOT alter or extend any of the intent patterns used by the core apps listed in section 3.2.3.1.
• Device implementations MAY include intent patterns using namespaces clearly and obviously associated with their own organization. This prohibition is analogous to that specified for Java language classes in section 3.6.

3.2.3.4. Broadcast Intents

Third-party applications rely on the platform to broadcast certain intents to notify them of changes in the hardware or software environment.

Device implementations:

• [C-0-1] MUST broadcast the public broadcast intents in response to appropriate system events as described in the SDK documentation. Note that this requirement is not conflicting with section 3.5 as the limitation for background applications are also described in the SDK documentation.

3.2.3.5. Default App Settings

Android includes settings that provide users an easy way to select their default applications, for example for Home screen or SMS.

Where it makes sense, device implementations MUST provide a similar settings menu and be compatible with the intent filter pattern and API methods described in the SDK documentation as below.

If device implementations report android.software.home_screen, they:

• [C-1-1] MUST honor the android.settings.HOME_SETTINGS intent to show a default app settings menu for Home Screen.

If device implementations report android.hardware.telephony, they:

• [C-2-1] MUST provide a settings menu that will call the android.provider.Telephony.ACTION_CHANGE_DEFAULT intent to show a dialog to change the default SMS application.

• [C-2-2] MUST honor the android.telecom.action.CHANGE_DEFAULT_DIALER intent to show a dialog to allow the user to change the default Phone application.

  • MUST use the user-selected default Phone app's UI for incoming and outgoing calls except for emergency calls, which would use the preloaded Phone app.

• [C-2-3] MUST honor the android.telecom.action.CHANGE_PHONE_ACCOUNTS intent to provide user affordance to configure the ConnectionServices associated with the PhoneAccounts, as well as a default PhoneAccount that the telecommunications service provider will use to place outgoing calls. The AOSP implementation meets this requirement by including a “Calling Accounts option” menu within the “Calls” settings menu.

If device implementations report android.hardware.nfc.hce, they:

• [C-3-1] MUST honor the android.settings.NFC_PAYMENT_SETTINGS intent to show a default app settings menu for Tap and Pay.

If device implementations support the VoiceInteractionService and have more than one application using this API installed at a time, they:

• [C-4-1] MUST honor the android.settings.ACTION_VOICE_INPUT_SETTINGS intent to show a default app settings menu for voice input and assist.

3.2.4. Activities on secondary displays

If device implementations allow launching normal Android Activities on secondary displays, they:

• [C-1-1] MUST set the android.software.activities_on_secondary_displays feature flag.
• [C-1-2] MUST guarantee API compatibility similar to an activity running on the primary display.
• [C-1-3] MUST land the new activity on the same display as the activity that launched it, when the new activity is launched without specifying a target display via the ActivityOptions.setLaunchDisplayId() API.
• [C-1-4] MUST destory all activities, when a display with the Display.FLAG_PRIVATE flag is removed.
• [C-1-5] MUST resize accordingly all activities on a VirtualDisplay if the display itself is resized.
• MAY show an IME (input method editor, a user control that enables users to enter text) on the primary display, when a text input field becomes focused on a secondary display.
• SHOULD implement the input focus on the secondary display independently of the primary display, when touch or key inputs are supported.
• SHOULD have android.content.res.Configuration which corresponds to that display in order to be displayed, operate correctly, and maintain compatibility if an activity is launched on secondary display.

If device implementations allow launching normal Android Activities on secondary displays and primary and secondary displays have different android.util.DisplayMetrics:

• [C-2-1] Non-resizeable activities (that have resizeableActivity=false in AndroidManifest.xml) and apps targeting API level 23 or lower MUST NOT be allowed on secondary displays.

If device implementations allow launching normal Android Activities on secondary displays and a secondary display has the android.view.Display.FLAG_PRIVATE flag:

• [C-3-1] Only the owner of that display, system, and activities that are already on that display MUST be able to launch to it. Everyone can launch to a display that has android.view.Display.FLAG_PUBLIC flag.