The use case diagram
The UML use case diagram: the use case (an actor's goal, named with a verb), the system boundary, the association between actor and use case, the include and extend relationships and generalisation.
- 23 cards
- 3 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- Questions
- Sort and link
A few cards from the deck
Use case: what is it?
Show the answer
A goal an actor pursues with the system that brings that actor a useful result, named with a verb: “Borrow a book”.
It is measured by the result for the actor, not by a technical action: “Enter a PIN” is a step, “Withdraw cash” is a use case.
A diagram links “Place an order” to “Log in” with a dashed include arrow. What does it mean?
- Every order goes through logging in
- Logging in only happens for some orders
- Logging in is a more general use case than placing an order
- An order can only be placed by a logged-in administrator
Show the answer
Every order goes through logging in
include means mandatory: the included behaviour runs every time. Optional behaviour would be drawn with extend.
The name of a use case starts with a … and expresses the goal of an ….
Show the answer
The name of a use case starts with a verb and expresses the goal of an actor.
“Book a room” is a well-named use case; “Booking form” describes a screen and “Bookings database” describes data.
Actor-use case association: what is it?
Show the answer
A plain line, with no dashed arrow, that links an actor to a use case it takes part in.
It says nothing about order or frequency: it only says that this actor is involved in that use case.
“Apply a promo code” extends “Place an order”. Which sentence is true?
- Every order must apply a promo code
- Only some orders apply a code
- Applying a promo code is a kind of placing an order
- Applying a promo code is a secondary actor of placing an order
Show the answer
Only some orders apply a code
The base use case “Place an order” is complete without the code: the added behaviour only runs if the extension condition is true (the buyer enters a code).