1.
Sequence Diagrams
Week 10

2.
Outline
Add scenarios to the system to describe how Use Cases are realized as interactions among societies of objects
Describe a scenario by applying sequence diagrams
c) Draw Sequence diagrams for given case studies

3.
Sequence Diagram
Sequence diagram represents the dynamic interaction between objects, or between actors and objects ordered in time.
A sequence diagram is composed of a timeline, objects that interact across this timeline, and the messages that they exchange.
Represent a scenario in the system

4. Major Ingredients of a Sequence Diagram
Major Ingredients of a Sequence Diagram
: Patient
1: enquiresAvailability
Message
Self Message
Focus of Control
Steps in the
Sequence
Notes
The Actor
Object
Time Line
aPatient :Patient
Patient Checks
Availability of Doctor

5.
How do you start?
Identify the process/algorithm/activity you want to capture( may be a use case)
Identify the major objects involved
Map out the flow of control/ messages to achieve the result

6. Relating Sequence Diagrams to Class Diagrams
Relating Sequence Diagrams to Class Diagrams
Objects on Sequence Diagrams belong to Classes in Class Diagram
aPatient:
Patient
Patient
1: checkPatientDetails( )
checkPatientDetails( )
Messages on Sequence Diagrams come from Methods available to the Class on Class Diagrams

7. A Layered Architecture
A Layered Architecture
Subsystems are shown as UML packages linked by dependencies
A dependency without a stereotype means uses

8.
Advancing the Sequence Diagrams from Analysis to Design: Showing specific objects
(B)
Design Sequence Diagram
Shows “Doctor” – a
Specific object
(A)
Analysis Sequence Diagram
Read “System”

9.
Representing objects

10. Message between objects
Message between objects

11.
More on messages

12. Indicating method calls
Indicating method calls

13.
Lifetime of objects

14. Understanding Focus of Control and return message
aPatient :
: Doctor
Patient
getSchedule( )
Focus of
Control
getAvailable( )
availability
Return
Protocol

15. Creating and Destroying an Object
: PatientForm
aPatient :
“Creating an Object”
Shown with the arrow pointing directly to the Object
Patient
bookConsultation( )
“Deleting an Object”
Shown with a Cross on the Timeline

19. Manage course information
Manage course information
The sequence of steps carried out in the "Manage course information" flow are:
A user who is a course administrator invokes the manage course functionality.
The manage course functionality of the course administrator invokes either the course creation or course modification functionality of a course.
After the course is either created or modified, the manage topic functionality of the course administrator calls the topic creation or modification functionality of a topic.
Finally, the user invokes the assign tutor to course functionality of the course administrator to assign a tutor to the selected course.
Now, let us model these steps into a Sequence diagram for the "Manage course information" functionality.

20.
the following use cases for the Courseware Management System were defined:
View courses
Manage topics for a course
Manage course information
View course calendar
View tutors
Manage tutor information
Assign courses to tutors

22.
Sketch a sequence diagram for the “normal” operation of an ATM (i.e. a customer inserts the card, enters his/her PIN, enters the amount, takes the card, and takes the money). The sequence diagram should show the interaction between the different components of the ATM. The ATM consists of the following components:
screen
keyboard
card reader
money tray
money output device
interface to banking server (for modifications of the account data of the customer)

24. Restaurant Example www.hndit.com Use Case: Have Dinner Scope:
Primary Actor:
Customer
Normal Flow:
1. Customer is seated at a table
2. Customer asks the waiter for the menu.
3. Customer orders drink(s).
4. Customer orders appetizer(s).
5. Customer orders main course(s).
6. Customer orders dessert(s).
7. Customer asks for the bill.
8. Customer pays the bill and receives change (if any).
Alternate Flow / Exceptions:
1.a Customer asks the waiter for his or her name.

27.
A sequence diagram fragment that contain an alternative combination fragment

28. A sequence diagram with a loop combination fragment
A sequence diagram with a loop combination fragment

29. Make Appointment Use Case-Analysis
Normal Flow:
1. Appointment clerk verifies that the needed medical service is provided by the hospital.
2. Appointment clerk records patient’s personal and contact data.
3. Appointment clerk records information about the referral source.
4. Appointment clerk consults hospital’s schedule to find a free slot for the required medical service.
5. Appointment clerk verifies that the patient is available for the appointment.
 Loop 1: Repeat steps 4-5 until hospital’s schedule matches patient’s availability.
6. Appointment clerk makes the appointment.
 Loop 2: Repeat steps 4-6 for each appointment.
Alternate Flow/ Exceptions:
2.a Patient is not on file. Create new patient. (Extend: Create Patient.)

31. UML Extension Mechanisms
UML offers a set of mechanisms that allow modeling to be refined, extended and adapted to specific needs.
Stereotyping is the specialization of standard UML notations.

32. UML Stereotyping
UML stereotyping is typically simple but powerful: If any building block of UML is not specialized enough to express your specific needs, you may specialize it yourself by specifying a tag and/or assigning an icon.

36. end