Create Request/Response DTOs for Application Services

[JavierCane]

What

Instead of instantiating the Value Objects directly from the controller, we should instantiate a DTO such as SignUpUserRequest and pass it to the Application Service.

The Application Services intended for querying data, we should return also a DTO such as UserResponse.

Why

This way we:

• Avoid coupling our entry points to the internal details on how we model out our domain (UserId value objects and so on).
• Leave the code on the Hexagonal Architecture approach closer to what we'll do while evolving to an architecture applying CQRS concepts. We will only need to:
  • Replace the XxxRequest by their corresponding XxxCommand,
  • Send the commands to the Command Bus instead of directly calling the Application Service
  • Implement the Command Handler in order to extract each one of the scalar values from the Command, convert them to Value Object instances, and call to the Application Service
  • Modify the Application Service in order to directly receive the Value Objects instead of the XxxRequest