Your are developing a software system to support a gas station. The owner of a gas station has given you the following description.

Before being able to pump gas, a user has to insert his/her credit card in the card reader and select the pre-payment option to authorize the fill-up amount of gas. After inserting the card the user has to enter a pin #. The pre-payment option then performs several operations in the background, such as verifying that the card is not damaged, connecting to the credit card processing system, to ensure that the card is not reported stolen. Next the user enters the amount to be pre-paid on the credit. The fuel pump card reader connects again to the external credit card processing and first checks if available balance on the card is sufficient to cover the gas purchase and to charge the card for the pre-payment amount.

Once the payment is approved, the user picks up the nozzle from the holster and starts fueling. The pump shows in different displays, the amount of fuel has been already pumped, the total $ amount and the number of liters left until the prepaid amount is reached. Once the prepaid amount is reached, fueling stops, the user returns the nozzle and a receipt is printed for the prepaid amount and the fueling is completed. In a case of a problem during the fueling, the system will stop the fueling and refund the credit card for the non-used amount.

The gas station attendant can monitor the fueling process of all pumps from the central control unit in the gas station building and stop fueling of any pump at any time.

Create a domain model for the above gas station problem (10 points)

Create a use case map which includes the pre-payment scenario the basic UCM notation is sufficient. You can use the jUCMNav for drawing. (10 points)

A simple instruction video can be found here: video

Create a use case diagram (10 points)