use cases

Question 1

what are use cases often used for

Answer 1

to derive functional requirements

Question 1

what is the best way to discover requirements and what are some limitations

Answer 1

talking to stakeholders

they may express them in their own terms
the can change their minds
system developers may make assumptions

Question 2

what is a use case

Answer 2

a behavioural model of a system
also a standard part of uml

Question 2

what do use cases consist of

Answer 2

use case model and use case diagram

Question 3

what are some positives of use cases (4)

Answer 3

graphical
you describe sample scenarios which are easy to discuss with the user
easy way to communicate between different stakeholders
used to derive test cases

Question 3

how are use cases represented in the model

Answer 3

ovals

Question 4

what does the box in a use case model represent

Answer 4

system boundaries

Question 4

how is a use case written

Answer 4

a verb noun phrase that represents where the system would be used

Question 5

actor

Answer 5

a user system or device that interacts with the system

Question 6

use case description

Answer 6

a sequence of steps that identifies what you need to do to complete a use case

Question 7

primary actor

Answer 7

the actor that wants to achieve the use case

Question 8

secondary actor

Answer 8

interacts with the use case in order to help the primary actor complete it

Question 9

precondition

Answer 9

activities that must take place before the use case can start

Question 10

flow of events

Answer 10

user actions and system responses that take place under the regular execution of the use case

Question 11

alternate flows

Answer 11

you must complete another task before going back to the flow of events

Question 12

post conditions

Answer 12

the state of the system when the use case has been completed

Question 13

why do we not use control statements and what do we use instead

Answer 13

it can make our description too algorithmic so we use scenarios instead

Question 14

primary scenario

Answer 14

what we expect to be normal behaviour

Question 15

secondary scenarios

Answer 15

reveal useful information e.g. exceptions

Question 16

«include»

Answer 16

adds one use case’s behaviour into another when it is mandatory

Question 17

«extend»

Answer 17

adds optional/conditional behaviour to another use case

Question 18

exceptions

Answer 18

scenarios where the postcondition cannot be fulfilled

Question 19

alternatives

Answer 19

different ways to fulfil the post conditions

Question 20

what are the 4 levels of use case detail

Answer 20

cloud level
sea level
fish level
bottom-of-the-ocean level

Question 21

could level

Answer 21

v high level summary - usually a business goal

Question 22

sea level

Answer 22

user goal; single sitting and the user gets a result

Question 23

fish level

Answer 23

include/extend goals

Question 24

bottom-of-the-ocean level

Answer 24

too low!!

Question 25

which levels are recommended for use cases

Answer 25

sea and fish level

Question 26

what is “weird” about non-functional requirements in use cases

Answer 26

the don’t appear explicitly in use cases
instead you can use simple annotations to add them in
e.g. nfr

Question 27

how do we deal with making use cases for overly complex systems

Answer 27

we can break them down into subsystems and each one can interact with another as an actor

Question 28

what is the main criteria for use case testing

Answer 28

there should be a test case for at least each flow in the use case