question

There are a couple of ways to do Push Notifications right now. One is via our Server API set (https://api.playfab.com/Documentation/Server/method/SendPushNotification), which is commonly used for sending player-driven events like telling a player that his score has been beaten by a friend, or that their base has been attacked. What you would is, when a player takes an action that could trigger a Cloud Script (to tell the other player something, usually) check in Cloud Script if there are any players that need to be notified, and send them the appropriate message.

The other is via PlayStream (https://playfab.com/features/#play-stream). Using PlayStream lets you trigger Actions based upon Events occurring in the service, which let you automatically do things like granting items or VC to players, setting statistics, calling a Cloud Script, or (as in this example) sending a Push Notification.

We'll also be providing ways to do bulk notifications to users in an upcoming update, including via our Add-ons Marketplace, with OneSignal.