Activity diagrams

This silde he;understand the rules and styles guidelines for activity diagrams.
Create functional model using activity diagrams.

1. Activity Diagrams
Week 4
TID2033

2. Chapter Objectives
After studying this chapter you should be
able to:
Understand the rules and styles guidelines
for activity diagrams.
Create functional model using activity
diagrams.

3. What Is an Activity Diagram?
Activity diagrams and use cases are logical
model which describe the business domain’s
activities without suggesting how they are
conduct.
A diagram that emphasizes the flow of control
from activity to activity in an object.

4. What Is an Activity Diagram? (cont…)
Similar to the traditional program flowchart.
Used to provide detail for complex
algorithms.
Portray the primary activities and the
relationships among the activities in a
process.

5. Drawing Activity Diagrams
Purpose
to model a task (for example in business
modelling)
to describe a function of a system represented by
a use case
to describe the logic of an operation
to model the activities that make up the life cycle
in the Unified Process

6. Synchronization bar – horizontal or
vertical bars denoting parallel or
concurrent paths of activities
Decision point – a diamond symbol
containing a condition whose results
provide transitions to different paths of
activities
Transition – a movement from one
activity or state to another
Activity
a behavior that an object carries out
while in a particular state
NewActivity
Elements of an Activity Diagrams

7. Notation of Activity Diagrams
Activities
rectangle with rounded ends
meaningful name
Transitions
arrows with open
arrowheads
Fill in registration form
Register subject

8. Notation of Activity Diagrams
Start state
black circle
Decision points
diamond
Guard conditions
in square brackets
Final state
black circle in white circle
[campaign to add]
[no campaign to add]
Add a New
Client
Assign Staff
Contact
Add New
Campaign

9. Notation of Activity Diagrams
Alternative notation for
branching:
alternative transitions
are shown leaving the
activity with guard
conditions
Note that guard conditions do not have to be
mutually exclusive, but it is advisable that
they should be
[campaign to add]
[no campaign to add]
Add a New
Client
Assign Staff
Contact
Add New
Campaign

10. Notation of Activity Diagrams
Object flows
dashed arrow
Objects
rectangle
with name of object
underlined
optionally shows the
state of the object in
square brackets
Record completion
of a campaign
:Campaign
[Active]
:Campaign
[Completed]

11. Notation of Activity Diagrams
Swimlanes
vertical columns
labelled with the
person, organisation
or department
responsible for the
activities in that
column
Record Completion
of a campaign
Issue invoice
Campaign
Manager
ClientAccountant
Pay invoice
Record client
payment

12. Activity diagram with
synchronization bars
Top synchronization bar
is a fork.
Bottom synchronization
bar is a join.

13. Guidelines for Creating
Activity Diagrams
Set the context or scope of the activity being
modeled.
Identify the activities, control flows, and
object flows that occur between the activities.
Identify any decisions that are part of the
process being modeled.
Identify any prospects for parallelism in the
process.
Draw the activity diagram.
Scott Ambler

14. Drawing Activity Diagrams
What is the purpose?
This will influence the kind of activities that are
shown
What is being shown in the diagram?
What is the name of the business process, use
case or operation?
What level of detail is required?
Is it high level or more detailed?

15. Drawing Activity Diagrams
Identify activities
Organise the activities in order with
transitions
Identify any alternative transitions and the
conditions on them
Add transitions and guard conditions to the
diagram

16. Drawing Activity Diagrams
Identify any processes that are repeated
Add transitions and guard conditions to the
diagram

17. Drawing Activity Diagrams
Are all the activities carried out by the same
person, organisation or department?
If not, then add swimlanes to show the
responsibilities
Name the swimlanes
Show each activity in the appropriate
swimlane

18. Drawing Activity Diagrams
Are there any object flows and objects to
show?
these can be documents that are created or
updated in a business activity diagram
these can be object instances that change state in
an operation or a use case
Add the object flows and objects

19. When Not to Use Activity
Diagram
An activity diagram should be avoided if:
The use case is simple and the graphical
representation will not be helpful
The purpose is to examine how object collaborate
– an interaction diagrams should be used instead.
The purpose is to see how an object behaves
over its lifetime. – used a statechart diagrams
instead

20. Summary
In this lecture you have learned about:
The purpose of activity diagrams
The notation of activity diagrams
How to draw activity diagrams

21. Let’s do
the
exercise

22. Dentist Office System
Create an activity diagram for the following dentist office
system. Whenever new patients are seen for the first
time, they complete a patient information form that asks
their name, address, phone number and brief medical
history, which are stored in the patient information file.
When a patient calls to schedule a new appointment or
change an existing appointment, the receptionist checks
the appointment file for an available time. Once a good
time is found for the patient, the appointment is
scheduled. If the patient is a new patient, an incomplete
entry is made in the patient file; the full information will be
collected when they arrive for their appointment. Because
appointments are often made so far in advance, the
receptionist usually mails a reminder postcard to each
patient two weeks before their appointment.

23. Use case name: Withdraw money
The use case is initiated by the customer. Customer
inserts the bank-card and enters PIN. ATM
SYSTEM authorizes the customer. ATM SYSTEM
will eject the card if the authorization is unsuccessful
and at the end of every transaction. Then the
customer will take the card and leave. If the
authorization is successful, ATM SYSTEM asks
customer “how much” and the customer enters the
amount and ATM SYSTEM checks if amount <=
balance. If yes, customer gets the money and ATM
SYSTEM updates balance. (Show two activities –
customer getting money and ATM SYSTEM
updating the balance as parallel events.) If amount >
balance, ATM SYSTEM displays an error message
and aborts the current transaction.