ddd-tactical-patterns

To model domain-driven design aggregates, define aggregate boundaries that encapsulate domain behavior and enforce invariants. Repositories should be positioned at the aggregate root to maintain consistency and prevent invalid state transitions across the domain layer.

You need domain events in a microservices architecture when meaningful state transitions occur within an aggregate. Emitting domain events allows event-driven domain logic to communicate changes across microservices without tightly coupling the services.

The best way to design immutable value objects is to validate concepts upon creation and ensure they remain unchanged. Immutability where appropriate guarantees that validated domain concepts maintain their integrity throughout their lifecycle.

Yes, domain-driven design works for layered architectures beyond microservices. Applying tactical patterns ensures clear boundaries, invariant enforcement, and rich domain behavior encapsulation within domain objects rather than controllers across any architectural style.

To start building an Order aggregate, create a minimal example that enforces an invariant and supports a submit action. The aggregate should emit a domain event upon state change to signal the transition to other parts of the system.