In Domain-Driven Design (DDD), the architecture is typically divided into several distinct layers, each with specific responsibilities. These layers help manage the complexity of software development by separating concerns and ensuring that each layer has a well-defined role. The primary layers in DDD are:
1. Presentation Layer (User Interface Layer)
The Presentation Layer is responsible for handling user interactions and presenting the user interface. This layer can take various forms, such as web interfaces, mobile applications, or desktop applications. It includes components like controllers, views, and templates that manage the display and input from users. The Presentation Layer communicates with the Application Layer to process user requests and display the results[2][3][8].
2. Application Layer
The Application Layer acts as a mediator between the Presentation Layer and the Domain Layer. It is responsible for orchestrating business processes and use cases, handling user commands, and coordinating the interactions between the domain objects. This layer does not contain business logic itself but rather calls upon the Domain Layer to execute business rules. It includes service classes that manage the flow of data and operations, ensuring that the correct domain objects are retrieved, manipulated, and persisted[1][3][6].
3. Domain Layer
The Domain Layer is the core of the software system, encapsulating the business logic, rules, and domain models. It represents the business entities, value objects, aggregates, and domain services that define the behavior and state of the application. This layer is where the business rules are implemented, and it should be independent of technical concerns such as data storage or user interface. The Domain Layer is designed to be highly cohesive and focused on the business domain, ensuring that it accurately reflects the business processes and rules[1][2][5].
4. Infrastructure Layer
The Infrastructure Layer provides the technical capabilities required by the other layers, such as data persistence, messaging, and external service integration. It includes components like repositories, data access objects (DAOs), and external service adapters. This layer is responsible for communicating with external systems, such as databases, message queues, and web servers. It implement...
