session-lifecycle

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Session state, stream state, pause and resume behavior, and device availability monitoring

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Session Lifecycle (Android)

Manage session and stream state in DAT SDK integrations.

Create a Session with Wearables.createSession(...), start it, then attach capabilities such as camera streaming. Session lifecycle and stream lifecycle are related but distinct.

Session states

State	Meaning	App action
`IDLE`	Session created, not started yet	Call `session.start()`
`STARTING`	Connecting to the device	Show loading UI
`STARTED`	Session active and ready for capabilities	Add or use capabilities
`PAUSED`	Session temporarily suspended	Keep state, wait for resume or stop
`STOPPING`	Session is shutting down	Stop user work and wait
`STOPPED`	Session ended	Release resources and create a new session if needed

Observe session state

val session = Wearables.createSession(AutoDeviceSelector()).getOrElse { error ->
    throw IllegalStateException(error.description)
}
session.start()

lifecycleScope.launch {
    session.state.collect { state ->
        when (state) {
            DeviceSessionState.STARTED -> onStarted()
            DeviceSessionState.PAUSED -> onPaused()
            DeviceSessionState.STOPPED -> onStopped()
            else -> Unit
        }
    }
}

Stream state

Camera streaming has its own state flow after you attach a stream:

STOPPED -> STARTING -> STARTED -> STREAMING -> STOPPING -> STOPPED -> CLOSED

lifecycleScope.launch {
    stream.state.collect { state ->
        // React to camera capability state changes
    }
}

Common transitions

The SDK may pause or stop a session when:

Another experience takes over the device
The user removes or folds the glasses
Bluetooth connectivity drops
The user unregisters the app or revokes needed access

Pause and resume

When a session is paused:

The device connection may remain active
Attached capabilities stop doing useful work
Your app should wait for the next observed session state instead of trying to force a restart

Device availability

lifecycleScope.launch {
    Wearables.devices.collect { devices ->
        // Update the list of available devices
    }
}

Use Wearables.devices and device metadata to decide when it is sensible to create a new session after a stop.

Checklist

Handle all DeviceSessionState values you care about
Observe stream state separately from session state
Release resources only after stop or close
Recreate sessions after terminal stops instead of reusing dead ones
Surface typed SessionError and StreamError failures