itsual Domain-Driven Design
Overview
DDD helps manage complexity by aligning the code model with the business domain and explicitly defining boundaries.
When to Use
- Complex business domains with rich rules
- Multiple teams working on related but distinct areas
- When the existing model is becoming a “big ball of mud”
Key Concepts
- Ubiquitous Language – Shared language between domain experts and developers
- Bounded Contexts – Explicit boundaries where a model applies
- Aggregates – Consistency boundaries
- Entities vs Value Objects
- Domain Events
- Anti-Corruption Layers when integrating with other systems
Practical Guidance
- Start with the domain, not the database or framework
- Keep aggregates small
- Prefer eventual consistency across aggregates when appropriate
- Use context maps to understand relationships between bounded contexts
- Don’t force full DDD on simple CRUD areas
Verification
- Core domain logic is expressed in domain terms
- Boundaries between contexts are clear
- Invariants are protected inside aggregates