Models and modelling
Models and modelling

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

6.10 To extend or include?

Whatever kind of system you intend to develop, you will need to consider its security. Usually, we allow only trustworthy people to use a new system. Therefore, in a software solution we can envisage a log-on use case, which describes how a user gains access through some authentication procedure. How should such a requirement be included in the example of the hotel chain?

By analogy with natural languages, the UML allows a number of ‘grammatically correct’ options each of which will make more or less sense depending on the context. For example, we could show the log-on use case as a component of every use case that is associated with an actor, as shown in Figure 7.

Figure 7
Figure 7 Including the log-on use case in the hotel domain

You can also redraw Figure 7, and produce Figure 8, showing the three original use cases as variations of the log-on use case. It would be ‘grammatically correct’ although it would be difficult for the reader to see the intended purpose of the system.

Figure 8
Figure 8 Making log-on the main use case

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371