Backend Design Patterns

Introduction

A short list of patterns you'll meet weekly in real Spring Boot codebases.

Understanding the topic

• Repository — abstract persistence behind interfaces.
• Strategy — interchangeable algorithms (PricingStrategy).
• Factory / Builder — complex object construction.
• Specification — composable query criteria.
• Observer / Event — Spring's ApplicationEventPublisher.
• Outbox — reliable event publishing alongside DB writes.
• Saga — long-running multi-service workflows with compensations.
• Circuit Breaker / Retry / Bulkhead — resilience.
• CQRS — separate read & write models for high-load systems.