Data Flow Diagram Balanced by vsn60759

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									Some errors and peculiarities in these diagrams include: (1) different names and numbers
are used for apparently the same data store on the two diagrams; (2) in the level-0
diagram, the data store, Class Roster, does not have the data flow, Scheduled Classes,
flowing into it, rather this data flow connects processes 2 and 3, thus these DFDs are not
balanced; (3) Process 1 appears to accomplish nothing because its inflow and outflow are
identical; such processes are uninteresting and probably unnecessary; it is possible that
this process will become interesting when it is decomposed, where validation and error
handling processes might appear; (4) Process 2 does not appear to need Course Request
as input in order to perform its function, as implied by its name, and (5) some students
may also wonder if Process 3 has input sufficient to produce its output. For example,
where are prior class registrations kept so that Process 3 can determine when a course is
Perfect Pizza wants to install a system to record orders for pizza and chicken wings. When
regular customers call Perfect Pizza on the phone, they are asked their phone number. When the
number is typed into a computer, the name, address, and last order date is automatically brought
up on the screen. Once the order is taken, the total, including tax and delivery, is calculated.
Then the order is given to the cook. A receipt is printed. Occasionally, special offers (coupons)
are printed so the customer can get a discount. Drivers who make deliveries give customers a
copy of the receipt and a coupon (if any). Weekly totals are kept for comparison with last year’s
performance. Write a summary of business activities for taking an order at Perfect Pizza.

A summary of the business activities for Perfect Pizza is:

                a.      Display customer record. Input is the customer number and the customer
                record. Output is customer information.

                b.     Take customer order. Input is the order information (including the
                customer number). Output is the total amount due for the order.

        a.      Send order to cook. Input is the customer order. Output is the cook's order.

                d.      Print customer receipt. Input is the customer order and the customer
                master record. Output is the customer receipt.

                e.      Deliver customer order. Input is the customer receipt and coupons.
                Output is the delivered receipt to the customer.

                f.     Print weekly totals. Input is the customer order and the previous year’s
                customer order summary. Output is the weekly performance figures.

1.      Draw a context-level data flow diagram for Perfect Pizza

        The context level diagram for Perfect Pizza is shown on the next page.

                         Phone Number

                         Customer Order              0              Performance Statistics

                                                                           Cook Order
      Customer        Customer Information     Customer
                                               Order System



2.    Explode the context-level diagram showing all the major processes. Call this Diagram 0.
     It should be a logical data flow diagram.

     Diagram 0 for Perfect Pizza is shown on the next page.
           Customer Information                                       Customer Record

                   Phone Number                                                         D1
                                             Find                                            Customer Master
Customer                                     Customer          Customer Record

              Customer Order                                                            D2
                                             T ake                                             Product File
                                             Customer             Product Price

                                                     T otal Order
                                                     Amount Due
              Customer Order                                                            D1
                                             Print                                           Customer Master
                                             Customer          Customer Record


    D3                                       Deliver                  Delivery
               Coupons                       Customer
                                  Coupons    Order                                            Customer

              Customer Order                                         Cook Order
                                            Send Order
                                            T o Cook                                            Cook

           Sales History File


                          Order Summary                        Performance Statistics
                          Record            Print Weekly
                                            T otals                                          Management
              Customer Order

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