You’re tagging this article with Ddd, is it the same as DDD which is Domain Driven Design? If it is not then your implementation of DDD is completely wrong. In your code the Domains folder contains services but it should contains the domain models. The domain classes. All those domain classes will model the real world (or additionals) version of the domain of the business where the software is designed for. The domain classes should contains the business rules of the domain.