Object-Oriented Software Development with UML - UNU-IIST ...

Use Cases: Describing Processes 354.2.3 Writing use casesWhen we use the methods given in the above subsection to identify a use case, we first create a high-leveluse case to obtain some understanding of the overall process, and then expand it by adding to it with moredetails.A high-level use case describe a process very briefly, usually in two or three sentences. They are often onlyconcerned with the events that the actors perform. It is described in the following format:Use case:Actors:Purpose:Overview:Cross References:Name of use case (use a phrase starting with a verb).List of actors (external agents), indicating who initiates the usecase.Intention of the use case.A brief description of the process.Related use cases and system functions.For example, the high-level description of the Buy Items with Cash process can be described as follows.Use case:Actors:Purpose:Overview:Cross References:Buy Items with CashCustomer (initiator), Cashier.Capture a sale and its cash payment.A Customer arrives at a checkout with items to purchase. TheCashier records the purchase items and collects a cash payment.On completion, the Customer leaves with the items.Functions: R1.1, R1.2, R1.3, R1.7, R1.9, R2.1.The references to the system functions indicate thatthe use case is created through further understanding of these functions,¢these required functions are allocated to this use case,¢This is useful that¢it is possible to verify that all system functions have been allocated to use cases,Report No. 259, July 2002UNU/IIST, P.O. Box 3058, Macau