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Service

In the context of hexagonal architecture, a domain service is a component that encapsulates domain-specific business logic that doesn’t naturally fit within the responsibilities of a single entity. Domain services handle operations that involve multiple entities or complex business rules that cross entity boundaries, providing a clean and cohesive interface for performing business operations.

Role of a Domain Service

  1. Encapsulation: Encapsulates complex business logic that spans multiple entities.
  2. Coordination: Coordinates operations involving multiple repositories, entities, and other services.
  3. Abstraction: Abstracts complex operations, providing a clear and cohesive interface for use cases.
  4. Reusability: Promotes reusability by isolating domain-specific logic that can be used across different use cases.

Components of a Domain Service

  1. Domain Model: The core business entities involved in the operations.
  2. Repository Interfaces (Output Ports): Interfaces for interacting with repositories that manage entities.
  3. Service Interface (Input Port): Defines methods for performing domain-specific operations.
  4. Service Implementation: Implements the business logic defined in the service interface.
  5. Adapters: Implementations of input and output ports to connect the service with external systems.

Benefits of a Domain Service

  1. Centralized Logic: Consolidates complex domain logic in one place.
  2. Reusability: Promotes reusability across different use cases and delivery mechanisms.
  3. Maintainability: Improves maintainability by isolating domain-specific logic.
  4. Testability: Enhances testability by decoupling business logic from external dependencies.

In hexagonal architecture, a domain service plays a crucial role in managing complex business logic that spans multiple entities. By encapsulating this logic and providing clear interfaces for interaction, the domain service ensures that the core application remains flexible, maintainable, and testable. This separation of concerns aligns with the principles of hexagonal architecture, promoting a clean and adaptable application design.

Service at Entity layer

If you have business logic that requires use more than one entity, please read Use Case or Exporting the Domain Service