Reference no: EM131279954

Draw a state machine diagram that represents the behavior of a simplified bank ATM based on the following description

The ATM is initially turn off. After the power is turned on the ATM performs start up action and performs a set of test on itself. If any of the test fail, the ATM sends a message to Maintenance and then goes out of service but doesn't turn itself off. IF it passes the tests the ATM becomes idle. It is now ready for use and it waits for customer interaction.

When a customer inserts a bank or credit card into the ATM's card reader it changes from idle to serving the customer. The ATM first reads the card to authenticate the customer. If the customer is not verified the ATM cancels the transaction, ejects the card and returns to waiting the customer. IF the customer is verified the ATM then displays a list of possible transactions. The customer chooses a transaction that the ATM then processes. Once transaction is complete the ATM finished serving the customer and ejects the card, and it then becomes idle and waits for another customer. The customer can also cancel the transaction at any time during the process. This also results in the card being ejected and the ATM returning to idle. Occasionally an ATM will fail to complete a transaction. IT then cancels the transaction , ejects the card and goes out of service to wait for maintenance.

ATMs are serviced both on a regular basis and also when they signal that they are out of service. Maintenance staff can switch the machine to its maintenance cycle when it is either idle or out of service. IF the maintenance is successful, the ATM then tests itself again and it then either goes out of service or becomes idle and waits for a customer .IF the maintenance is unsuccessful the ATM returns to being out of service. Maintenance staff can also turn off the ATM at any time whether it is idle or out of service.