Domain Services

Domain services encapsulate domain logic that doesn't naturally fit within an aggregate, entity or value object. Domain services are used to model operations and behaviors that involve multiple entities.

Domain services help to maintain a clean and organized domain model by offloading operations that don't belong to any specific entity.

Facts

Domain Services encapsulate domain logic.

Domain services contain business logic that spans multiple entities or value objects. They provide a place for operations that can't be naturally assigned to a single entity.

Domain Services enforce business rules.

Domain services can enforce business rules that apply to operations spanning multiple entities. They ensure that the rules are consistently applied across the domain model.

Domain Services should follow Ubiquitous Language.

The names of domain services should clearly indicate their purpose. A meaningful name helps to communicate the service's role within the domain model.

Domain Services coordinate operations.

Domain services often coordinate complex operations that involve multiple entities or value objects. They orchestrate the interactions between these objects to achieve a specific outcome.

Domain Services are stateless.

Domain services typically do not hold state. They operate on data provided to them and persist or return results without maintaining internal state between calls.

Domain Services define clear interfaces.

Domain services define clear and explicit interfaces, named to reflect the business functionality. These interfaces describe the operations that the service provides, making the service's role and capabilities clear.

Domain Services are invoked by application services.

Services in the application layer, like Application services, Command handlers, or Event handlers, invoke domain services to perform domain operations.