Are component interfaces mandatory for components in the component diagrams? If yes, can the interfaces really be very generic? For instance, a component may provide functionalities such as PayByCreditCard and PayByMileageAcct. Can that component expose one generic interface (say PaymentServices) rather than two specific interfaces. This should help me keep my component diagram relatively uncluttered. In fact it would really help if I did not include component interfaces at all, but would like to know if it's acceptable.