A use case describes interactions between an actor and a system to achieve a goal. It represents a discrete unit of functionality provided by the system. The key components of a use case include the actor, system boundary, and use cases within the boundary. An actor can be a person or external system. A use case should be written from the perspective of the actor and describe the measurable value or objective the actor wants to achieve through their interaction with the system. Use case diagrams are used during requirements gathering and analysis to identify the functional scope of the system and external factors that influence it from the viewpoint of users, not developers.

1. ?What Is A Use Case
a usage case is simply a reason to use a System
For example ,a bank cardholder might need to use
. an ATM to get cash from their account
.It s as simple as that

2. The purpose of use case diagram
So in brief, the purposes of use case diagrams can be
as follows:
 Used to gather requirements of a system (analysis
phase).
 A Use Case represents a discrete unit of interaction
between a user (human or machine) and the system
 describing a system from external usage viewpoint
not developer's perspective.
 Identify external and internal factors influencing the
system.

3. Use case diagram components
System boundary:
indicates the scope of
your system. Anything
within the box
represents functionality
that is in scope and
anything outside the box
is not
boundary
.
Use case:
Actor
use
case
relatio
n
Deposit cash
cardHolder
Actor:
An actor is a person, organization, or
external system that plays a role in
one or more interactions with your
system
relation:
To connect between the object
(communication)
A use case
describes a
sequence
of actions
that provide
something
of
measurable
value to an
actor

4. Actor



The actor describes a role not person
Actors don t have to be people. They can be other
systems. For example, the ATM may need to
connect to the cardholders bank
There are two kinds of actor - primary and
secondary.


Primary actor is anyone or thing that interacts with the system
to gain direct benefit.
Secondary actor is anyone or thing that involve in achieving a
use case yet, they do not gain direct benefit from the system.
Very often, secondary actor is someone who assist the
primary actor to achieve a use case.

5. (Use case (base



Deposit cash
The goal must be of value to the actor .
( enter PINs( don t build ATM s just so people
can enter their PINs
A use case is an objective user(s( wants to
achieve with a system. Use cases are named
with :
verb or verb + noun phrase.

6. ( Continuous ….. use case(basic
Tip for use case



simple title and describe the user goal
Verbs like 'do' and 'perform' and nouns like
'data' and 'information' should be avoided
whenever possible.
It is intended to provide an overview of what the
user want without knowing how to achieve the
goal
Deposit cash

7. (Continuous ….. use case( not basic

The <<include>> use case means that the
flow of that use case is always included

But a <<extend>> use case means that the
flow of the extending use case is only
included under specific conditions

8. (Continuous ….. use case( not basic

9. Example of wrong use cases

10. Example of wrong use cases

11. Example of wrong use cases

12. conclusion
the key questions we need to ask are;
who will be using the system, and what will
they be using it to do?
 Be one of the smart 1% and always
remember that use case designs aren t the
same thing as requirements
 Do not try to include all types of relationships.
Because the main purpose of the diagram is
to identify requirements.


13. ..……… Thank you
Written by : noor alshiyab
