The following describes a gas station system. Develop the gas station software context class diagram.

A gas station system provides the FastPass service, a payment service, where a driver pulls up at one of the Self-Serve fuel pumps equipped with the FastPass system. If a car has a FastPass tag, then a FastPass sensor on the pump detects its presence, reads the tags information, and lights up.

The information read from the FastPass tag is decoded at the pump and then sent from the pump to the FastPass central database. The system retrieves relevant credit card information it validates the FastPass tag. If the tag is valid, the credit card data is returned to the pump, which requests a bank to authorize the credit card. If the tag is invalid, the process terminates, and the FastPass light goes off. With the banks approval, the fuel pump is enabled, and the driver can pump gas. If the bank denies, the pump is not allowed, and the process terminates with the FastPass light going off.

If enabled, a driver selects the gass grade, and the driver refuels. The cost of gas is computed at the pump, and the amount is transmitted back to the bank, where it charges in the drivers card account. A receipt is issued at the pump, and the sale data is stored in the system. The pump returns to the idle state, displaying a welcome message, and prints a receipt.