Data Flow Diagrams (again)

1. Data Flow Diagrams (again) breaking it down…

2. Giz runs a car rental company and wishes to computerize the management of his growing organization. Before this can be done, her current activities must be diagrammatically represented. Those activities are listed below: Customer makes request in person/ by phone then the Rental clerk jots request down on form The form is stamped with today’s date & put on spike Manager collects spike periodically & records in the “Request book” by date of rental & updates ‘available cars’ book When customer comes in to receive car, he/ she signs ‘request book’ & makes payment When customer returns the car, it is evaluated and this evaluation is recorded, signed by customer, initialized by evaluator & ‘available cars’ book is updated If the returned car needs repair/ service, mechanic is called in and given the details of servicing/ repair. The ‘available cars’ records the location of the vehicle Payment for repairs are done in part by cheque The ‘available cars’ book is again updated when it is returned by mechanic; the 2nd payment is also made by cheque When the customer makes the first request, the manager checks the records to ensure it is available for that future date and calls customer if it is not.

3. First, let’s look at the question again: Giz runs a car rental company . Her current activities are listed (short hand) below: • Customer makes request • Rental clerk jots down request • Form is stamped & put on spike • Manager records data in the “Request book” • Manager updates ‘avail • When customer receives car, he/ she signs ‘request book’ & makes payment • Returned cars are evaluated • able cars’ book • Evaluation is recorded, signed & initialed • ‘available cars’ book is updated after this • Mechanic is called and given details if repairs are needed • ‘available cars’ records vehicle location • Payments for repairs are done in 2 parts by cheque • ‘available cars’ book is again updated when mechanic returns car • Manager checks availability and calls customer if car is not.

4. Level 0 • Identify all the persons OUTSIDE of our main activities • What are the main activities? Renting the car and all the operations that go with it. • Of course, you could disagree and put your assumptions to that effect. • Personally, I see the managers and rental clerks as a part of the system Mechanic Customer Evaluator

5. Widescreen Graphics Put them together with the central process (click)… And the data that goes to and comes from it … GizSys Repair info N.B. – the new additions to the DFD are in orange, the existing ones are blue

6. Moving to level 1 1. Keep everything other than the process (click)

7. Level 1 2. To create the level 1 DFD, look at each line in the narrative and determine what data is moved and to whom… • Customer makes request in person/ by phone • Rental clerk jots request down on form • Form is stamped with today’s date & put on spike (temporarystorage) • When the customer makes the first request, the manager checks the records to ensure it is available for that future date and calls customer if it is not. (click) Customer Availability Call Rental Request 1.3 Check availability 1.1 Take request 1.2 Stamp form Request Request On form

8. Level 1 N.B. – the new additions to the DFD are in orange, the existing ones are blue Again, look for the activities(click) 3. Then include any data stores you deem necessary (click): • If the returned car needs repair/ service, mechanic is called in and given the details of servicing/ repair. The ‘available cars’ records the location of the vehicle Mechanic Repair info 1.5 Call mechanic 1.4 Update car data update Available Cars Car details location Evaluation book State of car to be repaired

9. Level 1 4. Repeat the process until: • all the external entities from level 0 are represented • And all the data flows as well (click) • When customer returns the car, it is evaluated and this evaluation is recorded, signed by customer, initialized by evaluator (which I am assuming is in the evaluation report) Available Cars Update 1.6 Record evaluation Evaluation book Evaluation report Evaluation report Evaluator

10. Level 1 5. Ensure that all parts of the narrative are represented in the diagram or in the assumptions • Manager collects spike periodically & records in the “Request book” by date of rental (click) & updates ‘available cars’ book (click) • When customer comes in to receive car, he/ she signs ‘request book’ & makes payment • ‘available cars’ book is updated (click) • Payment for repairs are done in part by cheque( I have assumed that ‘payment’ means first and second cheques) Customer signature payment 1.8 Record return of car 1.7 Record payment 1.2 Stamp form Available Cars Payment details Stamped form info Request book Stamped form info

11. Level 1 • Time to tie up any loose ends • Ask yourself where the information comes from for each process and data store • And inversely, where it goes (click) 1.8 Record return of car Update info 1.3 Check availability Available Cars Request Availablility

12. Then add the evaluator info and you are DONE!! Request book Update info 1.7 Record payment Stamped form info Request On form Customer Available Cars Availability Call Mechanic 1.8 Record return of car 1.3 Check availability 1.5 Call mechanic update 1.4 Update car data 1.2 Stamp form 1.1 Take request Availability location 1.2 Stamp form Repair info Request Request Rental Request Car details payment State of car to be repaired Payment details Evaluation book signature R.Bk