Notification handling in background in Firebase - Step-by-Step Execution

Process Flow - Notification handling in background

App receives notification

↓

Is app in background?

No→Show notification in foreground

Yes↓

Background handler triggered

↓

Process notification data

↓

Show notification or update data silently

↓

User taps notification?

No→Wait

Yes↓

Open app or specific screen

When a notification arrives, the app checks if it is in background. If yes, a background handler processes it, showing notification or updating data silently. User interaction opens the app.

Execution Sample

Firebase

firebase.messaging().setBackgroundMessageHandler(async payload => {
  console.log('Message handled in the background!', payload);
  // Show notification or update data
});

This code sets a handler to process incoming notifications when the app is in the background.

Process Table

Step	App State	Notification Received	Action Taken	Result
1	Foreground	Yes	Show notification directly	User sees notification immediately
2	Background	Yes	Trigger background handler	Handler runs to process message
3	Background	Yes	Handler processes data	Notification shown or data updated
4	Background	User taps notification	Open app or specific screen	App opens to relevant content
5	Background	User does not tap	Wait	No immediate app action

💡 Notification handled based on app state; background handler stops after processing.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
App State	Foreground	Background	Background	Background	Foreground (after open)
Notification Received	No	Yes	Yes	Yes	Yes
Handler Triggered	No	Yes	Yes	Yes	No (after open)
Notification Shown	No	No	Yes	Yes	Yes
App Opened	No	No	No	Yes	Yes

Key Moments - 3 Insights

Why doesn't the notification show immediately when the app is in the background?

Because the background handler must first process the notification (see execution_table step 2 and 3), then it decides to show or update silently.

What happens if the user does not tap the notification?

The app stays in background and waits (execution_table step 5), no immediate action occurs until user interaction.

How does the app know to open a specific screen when the notification is tapped?

The background handler or notification payload includes data to navigate; tapping triggers app open with that data (step 4).

Visual Quiz - 3 Questions

Look at the execution table, what action is taken when the app is in the foreground and a notification arrives?

A Trigger background handler

B Show notification directly

C Wait silently

D Open app screen

💡 Hint

Check step 1 in the execution_table where App State is Foreground.

At which step does the background handler process the notification data?

A Step 3

B Step 1

C Step 2

D Step 4

💡 Hint

Look at the Action Taken column in execution_table for processing data.

If the user never taps the notification, what is the app's state after step 5?

A Foreground

B Closed

C Background

D Unknown

💡 Hint

See execution_table step 5: app remains in Background.

Concept Snapshot

Notification handling in background:
- App checks if it is in foreground or background on notification arrival.
- Foreground: show notification immediately.
- Background: trigger background handler to process.
- Handler can show notification or update data silently.
- User tap opens app or specific screen.

Full Transcript

When a notification arrives, the app first checks if it is in the foreground or background. If the app is in the foreground, it shows the notification immediately. If the app is in the background, it triggers a background handler that processes the notification data. This handler can show a notification or update app data silently without user interaction. If the user taps the notification, the app opens to the relevant screen. If the user does not tap, the app remains in the background waiting for further action.