From Xojo Documentation
Sends a notification named "Name".
Clients that have used the Listen method for the name will be get the notification. To receive notifications, call the CheckForNotifications method. Notifications are received in the PostgreSQLDatabase.ReceivedNotification event handler.
The Notify method does not have a way to send a payload. As a workaround you can call the command directly instead:
Send the "RefreshAll" notification: