Design patterns·Modelling the domain
the rule about when an order can be cancelled lives on the order, and there is exactly one copy of it.
Domain model
Also calledrich domain model, object model of the domain
An object model of the business in which the objects carry both the data and the rules that operate on it. It pays off when the rules are genuinely complicated and interlocking, because each rule has one home and the model can be tested without any infrastructure. It costs more than a transaction script up front and is the wrong choice for an application whose logic is mostly validation and storage.