architecture

Structure your Java Spring application by defining clear boundaries between Domain, Application, and Infrastructure layers. Implement DDD concepts like Aggregate Roots and Value Objects, and wire ports and adapters to isolate domain logic from external dependencies.

The best way to enforce dependency direction is by writing ArchUnit tests. These governance constraints automatically verify that infrastructure packages depend on domain ports, preventing incorrect layering and ensuring testability across the codebase.

Set up CQRS by separating your application services into distinct command and query handlers. This pattern isolates write operations from read operations, allowing you to optimize domain event processing and state mutations independently of query retrieval.

Hexagonal architecture works for Java Spring codebases of varying sizes. It provides pragmatic layering guidance, ensuring clear dependency direction and testability whether you are building a small modular service or a large complex domain model.

Implement event sourcing alongside CQRS when you need to persist state as a sequence of domain events. This combination allows you to reconstruct aggregate states from event logs while maintaining strict command and query separation.