# Backup UI Actors Reference

The `BackupUIParent` and `BackupUIChild` actors allow UI widgets to access
the current state of the `BackupService` and to subscribe to state updates.

UI widgets that want to subscribe to state updates must ensure that they are
running in a process and on a page that the `BackupUIParent/BackupUIChild`
actor pair are registered for, and then fire a `BackupUI::InitWidget` event.

It is expected that these UI widgets will respond to having their
`backupServiceState` property set.

```{js:autoclass} BackupUIParent
:members:
:private-members:
```

```{js:autoclass} BackupUIChild
```

% js::autoattribute:: BackupUIChild#inittedWidgets
% :members:
% :private-members: