One-to-one messaging in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is one-to-one messaging in system design?

One-to-one messaging is a communication system where messages are sent directly between two users without involving others. It ensures private and direct exchange of information.

beginner

Name two key components needed for a one-to-one messaging system.

1. User authentication to verify sender and receiver.<br>2. Message storage to save messages for delivery and history.

intermediate

Why is message delivery acknowledgment important in one-to-one messaging?

It confirms that the receiver got the message, improving reliability and user experience by showing message status like sent, delivered, or read.

intermediate

How does scaling affect a one-to-one messaging system?

As users grow, the system must handle more messages and connections. Scaling involves load balancing, efficient storage, and fast message delivery to keep performance smooth.

beginner

What role does encryption play in one-to-one messaging?

Encryption protects message content from unauthorized access, ensuring privacy and security between the two communicating users.

What is the main purpose of a message queue in one-to-one messaging?

A To display messages on the screen

B To temporarily hold messages before delivery

C To authenticate users

D To store user profiles

Message queues hold messages temporarily to ensure reliable delivery even if the receiver is offline.

Which component ensures only the intended user reads a message?

A Encryption

B Load balancer

C Message queue

D Database index

Encryption secures messages so only the sender and receiver can read them.

What does 'message acknowledgment' indicate in one-to-one messaging?

A Message was sent by the sender

B Message was received by the server

C Message was deleted

D Message was delivered to the receiver

Acknowledgment confirms the message reached the receiver successfully.

Which is a common challenge when scaling one-to-one messaging systems?

A Handling many simultaneous connections

B Creating user profiles

C Designing UI layouts

D Writing message content

Scaling must support many users connected at once without delays.

What is a typical way to store message history in one-to-one messaging?

A On the user's device only

B In-memory cache only

C Persistent database storage

D In the load balancer

Persistent databases store message history reliably for future access.

Explain the main components and flow of a one-to-one messaging system from sending to receiving a message.

Think about how a message travels securely and reliably between two users.

Describe how you would design a scalable one-to-one messaging system that supports millions of users.

Consider how to keep the system fast and reliable as it grows.