#Observer Pattern — 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

Low Level Design

Building a Scalable Weather Station

A Practical Look at Pub/Sub Architecture in Java

Easy·Nov 26, 2025

Low Level Design OOP Design Patterns

Low Level Design

How to Build a Scalable Music Service

Explore the system design of a music streaming service like Spotify. Learn about positional indexing for playlists, handling concurrency with the Actor model, low-latency playback architecture, and the design patterns that make it scale to millions of users.

Hard·Nov 24, 2025

Low Level Design OOP Design Patterns

Low Level Design

Observer Pattern — Event-Driven Design in Java

Build a type-safe, decoupled event system using the Observer pattern. Covers the classic GoF design, Java's built-in tools, and a modern generic implementation.

Jul 18, 2025·12 min read

Low Level Design Observer Pattern Design Patterns