Domain-Driven Design

Introduction

DDD is the playbook for complex domains: identify bounded contexts, model aggregates with strong invariants, communicate via events. It's how you keep banks, telcos and ERPs from collapsing under their own weight.

Understanding the topic

The vocabulary:

• Bounded Context — a subdomain with its own model & language.
• Aggregate — a cluster of entities/values guarded by an aggregate root.
• Value Object — immutable, equal by value (Money, EmailAddress).
• Domain Event — something meaningful that happened (OrderPlaced).
• Repository — collection-like access to aggregates.
• Ubiquitous Language — same words in code, tests, and standups.