Domainmallit

Domainmallit (domain models) are abstract representations of the concepts, rules, and processes of a particular domain, used to reason about and communicate aspects of the real world in software development. They focus on the core business logic, rather than user interface or infrastructure concerns.

In Domain-Driven Design (DDD), domain models are central. They rely on a ubiquitous language shared by developers and domain experts. The model typically includes entities (with identity and lifecycle), value objects (describing properties), aggregates (consistency boundaries), domain events, and domain services. Bounded contexts define clear boundaries where a model applies, helping manage complexity across large systems.

Modeling approaches range from a rich domain model that encapsulates behavior to an anemic model where logic resides outside the model; each approach has trade-offs. Notations such as UML class diagrams and textual descriptions are used to communicate the model. Iterative collaboration with domain experts helps refine invariants and rules.

Benefits of domain models include closer alignment with business needs, improved maintainability and testability of core rules, and clearer architectural boundaries. Challenges include added complexity, potential over-design, and difficulty evolving models in large systems. Models should capture business invariants and evolve with the domain while balancing stability and adaptability.

In practice, domain models are typically implemented as the domain layer of software, with persistence, user interfaces, and integration layers interacting through repositories, factories, and domain events. They support clear service boundaries and facilitate communication across bounded contexts.