Alternative Cases

Alternative cases arise when you wish the user to have a choice of possible actions. These choices are intentional, as they are wanted and defined by the business. They usually exist to make the work of the business use case more attractive and convenient to the participants. When you buy books or music online, for example, you can decide whether to place your selected goods in a shopping cart awaiting check-out or have them be sent directly to you whenever you click "buy." These choices are alternative cases.

Alternative cases arise when there is an intentional choice of user actions.

The work reacts differently depending on the selected alternatives. Consider step 4 of our example:

4. Attach the frequent-flyer number to the reservation.

A4.1 Attach the frequent-flyer number to the reservation.

You find alternatives by examining each step of the normal case. Look for instances where the step may be carried out differently or the actor can be given a choice. These choices are sometimes interesting from the point of view of improving the work or providing a better service.

4. Attach the frequent-flyer number to the reservation.

A4.1 Allow the FF number to be changed to that of a partner airline.

A4.2 Allow the FF number to be changed to that of a family member, or the mileage of the flight to be donated to a charity of the passenger's choice.