UML
Interaction Diagram and
Class Diagram
DUM 05
Historical perspective
What is UML?
• UML - Unified Modelling Language
• UML combines best of
– Data modelling concept (entity-relationship diagram, ERD)
– Manufacturing processes modelling (workflow diagrams)
– Object modelling
– Component modelling
• UML is a standardized language for description, specification,
construction and documentation of SW oriented system
artifacts
• It can be used for modelling processes during all phases of
development and for various implementation technologies
UML Concepts
UML allows to (among others):
– Display the borders of the system & its main functions
through Use cases and Actors
– Illustrate realisation of use cases with interaction diagrams
– Represent static structure of the system by the Class
diagram
– Model behavior of objects with State-Transition diagram
– Reveal physical implementation architecture using the
Component diagram
– Extend the functionality using Stereotypes
Use Case realisation
• Use Case diagram shows external view on the
system
• Interaction diagrams describe how are use cases
implemented as an interaction between groups of
objects
• Two types of interaction diagrams:
– Sequence diagrams
– Communication diagrams
Sequence diagrams
Sequence diagrams displays interaction between objects. This
interaction is ordered into a time sequence
Communication diagram
: Associate Dean
formC :
FormCourse
thisAdmin:
AdminCurriculum
this course:
Course
1: course information input
2: process
3: add course
4: new course
Communication diagram illustrates the interaction between
objects and their mutual interconnection
Class diagram
• Class diagram displays the existence of classes
and their relationships through the logic
perspective of a system
• UML modelling elements used in class diagrams:
– Classes, their structure and behavior
– association, agregation, dependency and inheritance
relationships
– Indicators of multiplicity and navigations
– Name of roles
Classes
• Class is a collection of objest with identical structure,
behavior and semantics
• Classes are found by re-examination of object in sequence
diagrams and collaboration diagrams. Class is depicted as
a rectangle with three sections
• Classes should be named using dictionary of the subjective
domain
• There should be a standard for creating classes names
– E.g. All classes will be in form of a singular noun with first capital
letter
Classes
RegistrationForm
RegistrationAdmin Course
Student
CourseOfferProfessor
PlanningAlgorithm
Operations
• Behavior of classes is represented by their operations
• Operations can be found after re-examination of
interaction diagram
Form
Registration
Admin
Registration
3: subscribeCourse(John, P007)
RegistrationAdmin
enrollCourse(student,Course)
Attributes
• A structure of the class is represented by its attributes
• Attributes can be found by re-examination of class
definition, requirements and by using knowledge of given
domain
Every course offer consists of
code, place and time
CourseOffer
code
place
time
Classes
RegistrationForm PlanningAlgorithm
RegistrationManager
enrollCourse(student,course)
Student
name
supervisor
Proffesor
name
department
Course
name
creditDonation
open()
enrollStudent (student)
CourseOffer
place
open()
enrollStudent (student)
Relationships
• Relationships provide channel for communication between
objects
• Sequence and/or cooperation diagrams are used to define the
connections between objects that are needed for certain
behavior – if some objects need to „talk“ to each other, then
there must be a relationship between
• There are 2 general types of relationships:
– Between classes
– Between instances
Relationship between classes
• Generalization / Inheritance is a strong relationship
between superclass and its subclasses
• E.g. Shape  [Triangle; Rectangle; Circle]
• Inherits attributes, methods, relationships
• Common attributes, operations and/or relationships are
shown at the highest applicable level of hierarchy
• Specialization / Dependency is a weak relationship where
client uses some methods of the provider but has no
semantic knowledge of the provider
Inheritance
name
RegistrationUser
RegistrationForm PlanningAlgorithm
RegistrationAdmin
enrollCourse(student,course)
Student
name
supervisor
Proffesor
name
department
Course
name
creditDonation
open()
enrollStudent (student)
CourseOffer
place
open()
enrollStudent (student)
specialization
aggregation
Relationships between instances
• Association is mutual connection between classes
• Association is represented by a link connecting related classes
• Aggregation is a form of weaker dependency, it portrays a relation
between whole and its parts, but the parts can exist on its own (e.g.
Student - University)
• Aggregation is represented by link connecting related classes, while
empty diamond sign is located next to class representing the whole
• Composition is a form of stronger dependency, where component
ceases to exist if the whole is deleted (e.g. Invoice – Item)
• Diamond sign is filled
Finding relationships
Relationships are found after re-examination of interaction
diagrams
– If two object „communicate“, then there must be a relationship
between them
P007:Course
Registration
Admin
3: addStudent(John)
Course
Registration
Admin
Relationships
RegistrationForm PlanningAlgorithm
RegistrationAdmin
enrollCourse(student,course)
Student
name
supervisor
Professor
name
department
Course
name
creditDonation
open()
enrollStudent (student)
CourseOffer
place
open()
enrollStudent(student)
Multiplicity and Navigation
Multiplicity defines how many objects are participating in the
relationship
•Multiplicity is a number of instances of one class with regard to
ONE instance of other class
•There must be two multiplicities for each association and
aggregation: for each end of the relationship
Although association and aggregation are implicitly
bidirectional, it might be suitable to restrict the navigation to
just one direction
The added arrow shows direction of navigation if restricted
navigation is applied
Multiplicity and navigation
RegistrationForm PlanningAlgorithm
RegistrationAdmin
enrollCourse(student,course)
Student
name
supervisor
Professor
name
department
Course
name
creditDonation
open()
enrollStudent (student)
CourseOffer
place
open()
enrollStudent(student)
0..*
1
1
0..*
1..*
4
3..10
0..41