6.1. Example
Informally, use cases are text stories of some actor using a system to meet goals. Here is an example brief format use case:
Process Sale:
A customer arrives at a checkout with items to purchase. The cashier uses the POS system to record each purchased item. The system presents a running total and line-item details. The customer enters payment information, which the system validates and records. The system updates inventory. The customer receives a receipt from the system and then leaves with the items.
Notice that use cases are not diagrams, they are text . Focusing on secondary-value UML use case diagrams rather than the important use case text is a common mistake for use case novices.UML use case diagrams p. 89 Use cases often need to be more detailed or structured than this example, but the essence is discovering and recording functional requirements by writing stories of using a system to fulfill user goals; that is, cases of use .[1] It isn't supposed to be a difficult idea, although it's often difficult to discover what's needed and write it well.
[1] The original term in Swedish literally translates as "usage case."