Push Notification Flow

A push notification flow describes the end-to-end path a message takes from your application server to a user's device screen, routing through Apple Push Notification service (APNs) on iOS or Firebase Cloud Messaging (FCM) on Android.

The process begins at first launch: the mobile app requests notification permission from the device OS. If the user grants permission, the OS contacts the platform gateway — APNs or FCM — and receives a unique device token. This token identifies the specific app installation on that specific device. The app then sends this token to your backend, which stores it associated with the user account.

When a server-side event warrants a notification — a new message, a status change, a promotional alert — your backend constructs a notification payload (title, body, optional data dictionary) and sends it to APNs or FCM along with the stored device token. The gateway authenticates the request, looks up the device, and delivers the notification to the device OS. The OS displays the notification in the system tray. If the user taps it, the OS launches the app and passes along any data payload from the notification.

Key failure modes to handle: device tokens rotate when an app is reinstalled or a user transfers to a new device, so your server must refresh tokens and handle BadDeviceToken rejections from APNs. FCM handles token invalidation similarly. For time-sensitive notifications where delivery latency matters, compare this polling-free push model against Realtime Messaging App Flow which uses persistent WebSocket connections, or the Mobile API Sync pull pattern for less latency-sensitive data updates.

An optional delivery acknowledgement step — where the app pings your backend on notification receipt — lets you track open rates and build retry logic for critical alerts.