Unlike the waterfall process for object design, with the iterative process programming starts before all of the requirements are expected. The Unified Process is a popular IDP which focuses on high risk / value parts first before creating full requirements for the program.
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Object Oriented Design Use Case
Use Case: Provide ATM user with money from checking account Scope: ATM Software Application Level: User Goal Primary Actor: Bank Customer Stakeholders and Interests 1. Bank Customer: a. Access to all the funds in both their savings and checking b. Deposit checks c. Check their balance while making sure their money is safe d. Receive a receipt 2. ATM: a. Provide funds available to customers b. Automatically update fund changes immediately c. Protect the bank and customers from false cards and PINs d. Monitor ATM activity via photos e. Verify all checks deposited f. Stay updated with home system in regards to changes in balances g. Provide a receipt after each transaction h. Shut down ATM if it no longer has enough funds on hand i. Report any oddities that may cause the home computer to shut it down i. Out of paper, dead key, cracked screen 3. Bank Home Office Computer: a. Provide accurate account funds information b. Update immediately when a transaction occurs system wide c. Decide to destroy card based on possible fraud d. Save photos taken e. Save a backup of all photos of checks f. Decide if machine should be shutdown and do so g. Decide if a technician needs to be sent to repair ATM h. Verify funds available in other banks if the user doesn't have an account with this bank ATM 4. Fraud Department: a. If sent card information they will verify if a card is stolen Preconditions a. A valid card is entered b. A valid PIN is entered that matches with the card Postconditions a. Customer is happy with the transaction b. The transaction is disseminated to all bank systems c. A photo of the customer is taken d. Receipt is generated e. Card is provided back to the customer Main Success Scenario 1. The ATM displays a message on screen identifying itself to customers 2. The customer inserts their card 3. The ATM verifies the legitimacy of the card 4. The Home Banking Office verifies the legitimacy of the card 5. The ATM takes a photo of the customer 5. The ATM requests that the customer enter their PIN 6. The ATM verifies the legitimacy of the PIN 7. The ATM asks the customer whether they want to remove funds or make a deposit 8. If the customer requests to remove funds the ATM asks if funds should be removed from checking or savings 9. Customer decides which account to remove funds from 10. The ATM asks the customer how much money to remove from the checking account 11. The customer enters the amount to remove 12. The ATM contacts the home office to verify if funds are available 13. The Home Office locks down the account from other transactions 14. The ATM informs the customer that a transaction is being processed 16. The ATM provides the specified funds to the user 17. The ATM asks the customer if they would like another transaction 18. The ATM repeats steps 8 thru 17 until the customer is finished 19. The Home Office is informed of the transaction 20. The customer receives a receipt 21. The customer receives their card 22. The ATM displays its welcome message for the next customer Extensions *a. At any time if the ATM runs out of funds 1. Display a closed message 2. Shut down the machine 3. Send a message that a technician needs to fill the ATM with funds *b. At any time if the ATM runs out of receipt paper 1. Display a closed message 2. Shut down the machine 3. Send a message that a technician needs to fill the ATM with receipt paper *c. At any time if the machine is damaged 1. Display a closed message 2. Shut down the machine 3. Send a message that a technician needs to fix the machine 3a. The card is from another bank 1. Connect to the other bank to verify funds a. The other bank isn't reachable 1. Inform the customer that a transaction can't be made 2. Provide the customer with their card 3. End the transaction b. The other bank is reachable 1. If the customer must pay a fee inform them of that i. Receive verification that the customer understands any fees 1. Add the fee as part of the transaction if customer allows 2. If customer declines record that and provide the customer with their card and a receipt 3b. The card is not valid for this ATM or any other partner banks 1. Contact fraud department to see if the card is stolen a. If the card is stolen 1. Confiscate the card 2. Take photo of the person using the ATM 3. Contact local law enforcement b. If the card doesn't come up as stolen 1. Inform the customer that a transaction can't be completed 2. Provide the customer with their card 3. Update the home office computer with the failed transaction 4. Provide a receipt to the customer 6a. The PIN is different from the PIN on file at the bank the card matched for 1. Ask the customer to re-enter their PIN (Repeat 3 Times) 2. Contact the fraud department to check if the card is stolen a. If card is stolen 1. Confiscate the card 2. Take photo of the person using the ATM 3. Contact local law enforcement b. If the card isn't stolen 1. Inform the customer that a transaction can't be completed 2. Provide the customer with their card 3. Update the home office computer with the failed transaction 4. Provide a receipt to the customer 12a. If the funds aren't available, ask customer if they want funds from other account 1. If they say yes, ask what account to check 2. If funds aren't available repeat 12a 3. If funds are available a. Inform ATM to process the transaction b. Mark the transaction in the home bank office Special Requirements 1. The text must be readable by color blind people 2. The text must be readable by people who speak other languages 3. The text must be readable from 3 feet away from the screen 4. The keypad buttons must include braille Data Variations List 1. All data uses 256-bit AES Encryption Frequency Occurrence Could be constantly Miscellaneous 1. Is there anything we can do to improve user experience for the blind? 2. Can polarized screens help improve security?