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2  Identify   use-  cases

 Use-  cases

 are the different things users of a system want it to perform. These can be 

described as activities or tasks that are part of a dialogue between an actor and the system. 

They summarise the requirements of a system from each actor since they describe the func-

tionality that will be provided by the system. Common  use-  cases are:

Actors

People, software or other 

devices that interface with 

a system.

 Use-  case

The sequence of 

transactions between an 

actor and a system that 

supports the activities of 

the actor.

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Part 3  Implementation

Figure 11.12

Relationship between actors and  use-  cases for a B2C company,  sell- 

 side e-commerce site

Customer

(actor)

Sales rep

(actor)

Customer service

(actor)

CRM system

(actor)

SOP system

(actor)

Browse

catalogue

Search

catalogue

Request

catalogue

Register

on-site

Purchase

on-site

Email

query

Cancel

order

● 

Starting up, shutting down or amending a system.

● 

Adding or amending information on a system. Examples include placing an e-commerce 

order or recording a complaint via email.

● 

Using a system for reporting or decision support.

Some  use-  cases for a B2C company are shown in Figure 11.12.

Bevan (1999b) also notes the importance of defining key scenarios of use. This stage, 

often known as ‘knowledge elicitation’, involves interviewing users and asking them to talk 

through their current or preferred way of working. Once the scenarios have been established, 

card sorting techniques, as described by Noyes and Baber (1999), can be used. They describe 

how after interviewing users, typical tasks or actions were written down on cards. These 

were then used to identify the sequence of actions users required from a menu system. They 

explain that the menu system devised was quite different from that envisaged by the software 

engineers. Card sorting techniques can also be used to check that no stages have been missed 

during the