These rules are encoded in the Service Layer.

In the first example, when saving the order, you 1) save the order, and then 2) evaluate all the rules and update the user's record. These actions should be bracketed by a Transaction, which is also done in the Service Layer.

Second example also takes place in the Service Layer. When requesting approval for a mortgage you have a method on the Service Layer that evaluates all the conditions and renders a final answer back to the user.

Hope this helps.