Why should you care?

Users expect proactive updates; systems need decoupled delivery from core transaction path.

See it live — copy this example

Paste into your MeanVerse project (Angular + Express + MongoDB), then run with ng serve / node / mongosh as noted.

// after transfer commits
await notificationQueue.add('send', {
  userId: user.id,
  channels: ['inApp', 'email'],
  template: 'transfer-complete',
  data: { amount: transfer.amount, last4: account.last4 }
});

// worker
async function processNotification(job: Job) {
  if (job.data.channels.includes('inApp')) {
    await InAppNotification.create({ userId: job.data.userId, body: render(job) });
    io.to(`user:${job.data.userId}`).emit('notification', { body: render(job) });
  }
  if (job.data.channels.includes('email')) await ses.sendEmail(/* ... */);
}

What happened?

• Queue decouples API response from email latency.
• Worker writes in-app doc and emits Socket.IO.
• Templates keep content consistent.

Practice next

1. Define notification preferences per user in MongoDB.
2. Enqueue job after successful domain event.
3. Build Angular notification bell subscribing to socket.
4. Add digest mode batching hourly emails.
5. Store read/unread state on InAppNotification.

Remember

Notify async via queue workers. Multi-channel: in-app + email + push. User prefs control channel selection.

Healthcare appointment

Patient gets SMS 24h before visit via queued worker.

Outcome: API books appointment in 200ms; SMS sends in background.