Question

I am trying to make a use case diagram for library management system. I have two actors admin and user.

Now, the admin has three functions manageCategories (of books like history, geography etc.) manageUser and manageBooks..

What I am doing is considering these 3 functions in a single function manage i.e manage is a single use case.

How should I consider the three functions managerUser, manageBooks, manageCategories in the diagrams?

Should I use include or extend the three functions in a single use case manage, or use anything else?

Answer 1

Edited after the corrects comments of @vainolo about the included use case confusion in my answer:

If the manage use case needs the callable use cases (managerUser, manageBooks, manageCategories) in order to make sense (produce value) for the main actor, then you should use the include relationship.

If the actor can complete the manage use case executing zero or all three of the callable use cases (managerUser, manageBooks, manageCategories) then you should use the extend relationship and you may specify the extension point conditional statements for them.

If the manage use case is a container used to organize the three callable use cases which can be executed independently, then I’d modelize manage as a Use Case Package containing the three use cases rather than a use case per se.

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Please find the following excerpt from that post about the NOT mandatory execution of an included use case (as correctly pointed out by @vainolo):

Point 5: Inclusion use cases may be optional

A UML superstructurestatement Section 16.3.5 of 2 states:

“Note that the [inclusion] use case is not optional, and is always
required for the [base] use case to execute correctly.”

Cause for confusion

Some seem to interpret this to mean that an inclusion use
case must be performed during each and every execution of a base use
case.

Nothing is further from the truth and the truth is simple.

The simple truth

Whether an inclusion use case is mandatory or
optional to a base use case depends on where in the base use case the
fragment was defined that is now replaced with an include statement
for the inclusion use case.

If that fragment was part of the base use case’s unconditional flow
(steps that always get executed), the inclusion use case is mandatory.
If that fragment was part of a conditional flow (steps that get
executed optionally), the inclusion use case is optional.

So what does the UML statement mean?

The purpose of the UML statement seems to
be to contrast the include relationship with the extend relationship,
as follows.

At an extension point (not for the entire base use case), the
extension use case’s execution is optional.

When the execution of a base use case reaches an extension point, an
extension use case may or may not be inserted, because there may be a
condition attached to the extend relationship. However, at an
“inclusion point” (not for the entire base use case), the inclusion
use case’s execution is mandatory.

When the execution of a base use case reaches an inclusion point
(i.e., an include statement in the base use case), the inclusion use
case will always be performed, because there is no provision for
attaching a condition to the include relationship.