AMU handles Alarms, like everything else in the connected MS SQL database, so you don't have the option to use standard ThingWorx property change events or subscriptions on alert definitions.
You have two options:
- If you want to "subscript" to an alarm notification, you can customize the Action Type settings on the Core Configuration thing. This configuration table lists the option that the user has when creating an alarm definition in AMU. By default you will only see "SendEmail", but you could add an option and then select that option when you create a new Alarm definition in AMU. When a alarm gets triggered AMU would then call your custom service on the configured Thing and passes over an JSON that has information about the Alarm, that you can process and do what you want with it.

- If you are not really looking to "subscript" to Alarms but just want to list Alarms in your custom mashup, you can simply use the "QueryAlarms_ALM" service on the PTC.FSU.CORE.Alarm.Utils_TG thing.
