It contains the Client Action, with the necessary Javascript, to initialize the user to the notifications and save his correspondent Onesignal Id (PlayerId), needed to send notifications to a specific user.

The Player Id is stored in a the UserNotificationInfo and can be retrieved using the GetPlayerId Server Action.

The OneSignal App Id, API Key and Safari Web Id, should be stored in the correspondent Site Property.

To send notifications, OneSignal Notification Plugin can be used.