So let's start with the Domain layer. The Domain layer typically consists of a domain model. So what is a domain model? A domain model is a representation of the data storage types required by the business logic. It describes the various domain objects (entities), their attributes, roles, and relationships, plus the constraints that govern the problem domain. You can look at the following order processing domain model diagram to get a quick idea about the domain model.
Each block in the previous diagram represents a business entity and the lines represent the associations between the entities. Based on this domain model diagram, you should understand that in an order processing domain, a Customer can have many Order and each order can have many OrderItem and each OrderItem represents a single Product.
During actual coding and development this domain model, will be converted into corresponding domain objects and associations by a developer. A domain object...