1. IS424 - Assignment#1 DFD + Use-Cases Kingdom of Saudi Arabia
Ministry of Higher Education
Princess Noura bint Abdulrahman University
College of Computer & Information Sciences
IS424 - Assignment#1
DFD + Use-Cases
T. Shatha AlAjlan

2. Exercise#1
For the following situation, draw a context-level diagram and a level-0 data flow diagram.
Kellogg State Bank provides car and home loans to its banking customers. Initially, a potential loan customer meets with a Kellogg loan officer, requests a loan for a certain amount and time frame, and completes a loan application. Next, the loan officer determines the customer’s credit standing, the type of loan required, and available interest rates. While the loan officer can authorize car loans for credit worthy customers, a loan committee must approve all home loans.

3. Solution
A suggested context-level data flow diagram is provided below.

4. Solution (cont.)
A suggested level-0 data flow diagram is provided below.

5. Exercise#2
A university wishes to increase security in its car park. It has been decided to issue an identity card to all employees. The cards record the employee’s name, department and identity number . A barrier, a card reader and a sensor are placed at the entrance of the car park. The driver inserts the numbered card into the card reader. The card reader checks the card number. If the number is valid, the reader sends a signal to raise the barrier and the vehicle can enter the car park. The sensor sends a signal to the barrier to lower when the vehicle has entered. There is a system at the exit with a barrier which is raised when a car wishes to leave the car park. When there are no spaces in the car park a sign at the entrance displays “Full” and is only switched off when a vehicle leaves. Special visitors’ cards, which record a number and the current date, also permit access to the car park. Visitors’ cards may be sent out in advance or collected from reception. All visitors’ cards must be returned to the reception when the visitor leaves the site so that they can be deleted from the list of valid cards.

6. Solution
Draw a UML use case diagram for the university car park system.

7. Solution (cont.)
Write the flow of events for one of use cases . ( Enter Car Park )
Use Case#1
Use Case Name : Enter Card Park
Use Case Description : a driver Enter card to card reader then to car park
Primary Actor : driver
Secondary Actor :System
Pre-Conditions : 1.Driver should have a valid card
Post-Conditions 1.car enter car park

8. Solution (cont.)
Write the flow of events for one of use cases . ( Enter Car Park )  primary flow of event (normal)
Request
Response
1. The driver inserts his/her card.
2. The card reader reads the card number. 3. The system checks if the card number is in the list of valid card numbers. 
4. The system checks if there is a space. 5. sends a message to the barrier to lift up. 6. The sensor sends “car passed” message to the system. 7. The sensor sends a message to the barrier to lower. 8. The system decreases the number of available spaces by 1.

9. Solution (cont.)  Alternative flow of event Request Response
1. The driver inserts his/her card.
2. The card reader reads the card number. 3. The system checks if the card number is in the list of valid card numbers.  4. The system checks if there is a space. ( if The car park is full. ) 5.A sign at the entrance displays “Full” 6.switched off when a vehicle leaves.

10. Solution (cont.)  Error flow of event Request Response
1. The driver inserts his/her card.
 5.Driver re-enter his/her card
2. The card reader reads the card number. 3. The system checks if the card number is in the list of valid card numbers.  ( if the system can’t check) 4. The system restart The card reader reads the card number. 7. The system checks if the card number is in the list of valid card numbers. 
8. The system checks if there is a space. 9. sends a message to the barrier to lift up. 10. The sensor sends “car passed” message to the system. 11. The sensor sends a message to the barrier to lower. 12. The system decreases the number of available spaces by 1.