We are currently implementing IAP into our Amazon App. Users will be using recurring subscriptions. Currently the only mechanism we have to determine the status of a subscription is to poll RVS. But if for example there are a 1000 users, we would have to poll 1000 times in frequent intervals to have an up to date picture of status of users subscribing to our service. Is there some sort of a push mechanism in which Amazon can inform our servers if there is a status change with users who are subscribed to our service?