Notification system in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the primary purpose of a notification system in software architecture?

To deliver timely messages or alerts to users or systems about events or updates, ensuring they stay informed and can take necessary actions.

beginner

Name two common types of notifications in a notification system.

Push notifications (sent to devices or browsers) and email notifications (sent via email).

intermediate

Why is it important to decouple the notification sender from the notification processor?

Decoupling allows the system to handle high loads better, improves scalability, and makes maintenance easier by separating concerns.

intermediate

What role does a message queue play in a notification system?

It acts as a buffer to hold notification tasks, enabling asynchronous processing and smoothing out spikes in notification requests.

advanced

How can a notification system ensure reliability and avoid losing notifications?

By using persistent storage for messages, retry mechanisms for failed deliveries, and acknowledgments to confirm receipt.

Which component is best suited to handle spikes in notification requests?

A Database

B Message queue

C Load balancer

D User interface

Message queues buffer incoming requests and allow asynchronous processing, helping to handle spikes smoothly.

What is a common way to send push notifications to mobile devices?

A Using SMTP protocol

B Using FTP servers

C Using HTTP GET requests only

D Using Firebase Cloud Messaging (FCM)

Firebase Cloud Messaging is a widely used service to send push notifications to mobile devices.

Why should notification sending be asynchronous?

A To block the main application flow

B To avoid using databases

C To improve user experience by not delaying responses

D To reduce the number of notifications

Asynchronous sending prevents delays in the main application, improving responsiveness.

Which of the following is NOT a notification channel?

A Database indexing

B SMS

C Push notification

D Email

Database indexing is a data optimization technique, not a notification channel.

What is a key benefit of using a retry mechanism in notification delivery?

A To ensure notifications are eventually delivered despite temporary failures

B To send duplicate notifications

C To reduce system load

D To avoid using message queues

Retry mechanisms help deliver notifications even if initial attempts fail temporarily.

Explain the main components of a scalable notification system and how they interact.

Think about how messages flow from creation to delivery without blocking the main app.

Describe strategies to ensure reliability and fault tolerance in a notification system.

Consider what happens if a notification fails to send or the system crashes.