The following diagram clearly identifies where the request handling layer resides in the overall application architecture:

The request handling layer accepts client requests and forwards the respective action to the appropriate service layer method. The returned DTO (or Value Object as it is also known in Domain-Driven Design) is examined and an appropriate response is then sent to the client. Unlike the historical server-side MVC programming, the request handling layer has no knowledge of presentation and simply acts as a request-processing interface to the application.