#Pub-Sub — ByteDepth

Low Level Design

Design a Notification Service

A multi-channel notification broker with per-service subscription control, parallel fan-out via an ExecutorService, exponential-backoff retry, and a Dead Letter Queue — built around Template Method, Strategy, Builder, and Singleton.

Medium·Aug 16, 2026·16 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Pub-Sub Model

Build a Publisher-Subscriber messaging system from scratch — decoupled components, dynamic topic management, and thread-safe broadcast using the Observer pattern and Singleton registry.

Medium·Aug 16, 2026·12 min read

Low Level Design OOP Design Patterns

High Level Design

Kafka

Kafka's architecture, core components, partitions, ISR-based durability, trade-offs, and when to use it over RabbitMQ or SQS.

Aug 10, 2026

System Design Kafka Message Queue

High Level Design

Message Queues

How message queues decouple producers and consumers, core components, edge cases like poison messages and duplicates, and popular implementations.

Aug 10, 2026

System Design Message Queue Async

High Level Design

Design a Notification System

End-to-end design of a scalable notification system — iOS/Android push, SMS, email, message queues for async delivery, reliability, deduplication, and the improved multi-server architecture.

Aug 10, 2026

System Design Notifications Push