Supporting Multiple Users

Supporting Multiple Users

This document describes the Android multi-user feature. It allows more than one user on a single Android device by separating their accounts and application data. For instance, parents may let their children use the family tablet. Or a critical team might share a mobile device for on-call duty.

Definitions

Before supporting multiple Android users, you should understand the basic concepts involved. Here are the primary terms used when describing Android users and accounts:

• User - Each user is intended to be used by a different physical person. Each user has distinct application data and some unique settings, as well as a user interface to explicitly switch between users. A user can run in the background when another user is active; the system manages shutting down users to conserve resources when appropriate. Secondary users can be created either directly via the primary user interface or from a Device Administration application.
• Account - Accounts are contained within a user but are not defined by a user. Nor is a user defined by or linked to any given account. Users and profiles contain their own unique accounts but are not required to have accounts to be functional. The list of accounts differs by user. See the Account class definition.
• Profile- A profile has separated app data but shares some system-wide settings (for example, Wi-Fi and Bluetooth). A profile is a subset of and tied to the existence of a user. A user can have multiple profiles. They are created through a Device Administration application. A profile always has an immutable association to a ‘parent’ user, defined by the user that created the profile. Profiles do not live beyond the lifetime of the creating user.
• App - An application’s data exists within each associated user. App data is sandboxed from other applications within the same user. Apps within the same user can interact with each other via IPC. See Building Apps for Work.

User types

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• Primary - The first user added to a device. The primary user cannot be removed except by factory reset. This user also has some special privileges and settings only it can set. The primary user is always running even when other users are in the foreground.
• Secondary - Any user added to the device other than the primary user. They can be removed by either themselves or the primary user and cannot impact other users on a device. Secondary users can run in the background and will continue to have network connectivity when they do.
• Guest- A guest user is a temporary secondary user with an explicit option to quick delete the guest user when its usefulness is over. There can be only one guest user at a time.

Profile types

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• Managed- Managed profiles are created by an application to contain work data and apps. They are managed exclusively by the ‘profile owner’, the app who created the corp profile. Launcher, notifications and recent tasks are shared by the primary user and the corp profile.
• Restricted - Restricted profiles use the accounts based off the primary user. The Primary user can control what apps are available on the restricted profile. Restricted profiles are available only on tablets.

Effects

When users are added to a device, some functionality will be curtailed when another user is in the foreground. Since app data is separated by user, the state of those apps differs by user. For example, email destined for an account of a user not currently in focus won’t be available until that user and account are active on the device.

The default state is only the primary user has full access to phone calls and texts. The secondary user may receive inbound calls but cannot send or receive texts. The primary user must enable these functions for others.

Note: To enable or disable the phone and SMS functions for a secondary user, go to Settings > Users, select the user, and switch the Allow phone calls and SMS setting to off.

Please note, some restrictions exist when a secondary user is in background. For instance, the background secondary user will not be able to display the user interface or make Bluetooth services active. Finally, background secondary users will be halted by the system process if the device needs additional memory for operations in the foreground user.

Here are aspects of behavior to keep in mind when employing multiple users on an Android device:

• Notifications appear for all accounts of a single user at once.
• Notifications for other users do not appear until they are active.
• Each user gets his or her own workspace to install and place apps.
• No user has access to the app data of another user.
• Any user can affect the installed apps for all users.
• The primary user can remove apps or even the entire workspace established by secondary users.

Implementation

Managing users

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Management of users and profiles (with the exception of restricted profiles) is performed by applications that programmatically invoke API in the DevicePolicyManager class to restrict use.

Schools and enterprises may employ users and profiles to manage the lifetime and scope of apps and data on devices. They may use the types outlined above in conjunction with the UserManager API to build unique solutions tailored to their use cases.

Applying the overlay

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The multi-user feature is disabled by default in the Android 5.0 release. To enable it, device manufacturers must define a resource overlay that replaces the following values in frameworks/base/core/res/res/values/config.xml:

<!--  Maximum number of supported users -->
<integer name="config_multiuserMaximumUsers">1</integer>
<!--  Whether Multiuser UI should be shown -->
<bool name="config_enableMultiUserUI">false</bool>

To apply this overlay and enable guest and secondary users on the device, use the DEVICE_PACKAGE_OVERLAYS feature of the Android build system to:

• Replace the value for config_multiuserMaximumUsers with one greater than 1
• Replace the value of config_enableMultiUserUI with: true

Device manufacturers may decide upon the maximum number of users.

That said, if device manufacturers or others have modified settings, they need to ensure SMS and telephony work as defined in the Android Compatibility Definition Document (CDD).