Given the informal requirements for a Milk Delivery System, produce data flow diagrams at various levels of refinement: A system is to be produced that holds details of deliveries of several brands of...

Given the informal requirements for a Milk Delivery System, produce data flow diagrams at various levels of refinement: A system is to be produced that holds details of deliveries of several brands of milk in a small town. As well as recording which households take which brand(s) of milk, this system also includes billing information and details of customer vacations when milk will not be delivered. The household phones the delivery company to change personal information, such as the address, to inform the company of vacation, and to change the milk order. For each delivery person, the system prints a daily list of which brands of milk are to be delivered to which households. The system should also be able to produce summary information showing how many liters of each type of milk are sold each day in the week. Customer bills are printed at the end of each month and delivered with the first delivery of the following month. The system should also produce error messages, confirmations, and warnings. Produce a use case model including one or more UCDs. Provide a detailed description of two use cases of your choice.