Uml

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SOFTWARE ENGINEERING II
Lecture VIII- Part 2
COMSATS Institute of Information Technology Computer Science
Department
Syed Faraz Ahmad,
MS (Computer Science)
CIIT Abbottabad
comsian032@gmail.com

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UML Defined
• The Unified Modeling Language (UML) is a
general purpose visual modeling language that is
used to specify, visualize, construct, and document
the artifacts of a software system.
Source: Rumbaugh, Jacobson, Booch, Unified Modeling Language Reference Manual (Addison-Wesley, 1999), p.
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UML Defined
• It captures decisions and understanding about
systems that must be constructed.
• It is used to understand, design, browse, configure,
maintain, and control information about systems.
• It is intended to be used with all development
methods, lifecycle stages, application domains,
and media.
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Goals of UML
 There were a number of goals behind the development
of UML:
 UML is a general-purpose modeling language that all
modelers can use.
 It is meant to include the concepts of the leading methods so
that it can be used as their modeling language.
 It was intended to be as familiar as possible.
 It is meant to support good practices for design such as
encapsulation, separation of concerns, and capture of the
intent of a model construct.
 It is intended to address current software development
issues, such as large scale, distribution, concurrency,
patterns and team development.
 It was to be as simple as possible while still being capable
of modeling the full range of practical systems that need to
be built.
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UML Building Blocks
• UML is composed of three building blocks:
– Things
• These are the modeling elements
– Relationships
• These tie things together
– Diagrams
• These are views into UML models
Source: Booch, The Unified Modeling Language User Guide (Addison-Wesley, 1998), p. 2.

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UML Things
 UML thing may be partitioned into:
 Structural things
 Represent the nouns of a UML model such as class,
component, use case, etc
 Behavioral things
 Represent the verbs of a UML model such as
interactions, states, etc.
 Grouping things
 Represent things that group elements together such as the
package.
 Annotational things
 The note
Source: Arlow and Neustadt, UML and the Unified Process (Addison-Wesley, 2002), p. 9.

Relationships
In UML, object interconnections
(logical or physical), are modeled as relationships.
There are three kinds of relationships in UML:
• Dependencies
• Generalizations
• Associations

Dependency Relationships
CourseSchedule
add(c : Course)
remove(c : Course)
Course
A dependency indicates a semantic relationship between
two or more elements. The dependency from
CourseSchedule to Course exists because Course is used
in both the add and remove operations of
CourseSchedule.

Generalization
Relationships
Person
A generalization connects a subclass
to its superclass. It denotes an
inheritance of attributes and behavior
from the superclass to the subclass and
indicates a specialization in the
subclass of the more general
superclass.Student

Generalization Relationships (Cont’d)
Student
UML permits a class to inherit from multiple superclasses,
although some programming languages (e.g., Java) do not
permit multiple inheritance.
TeachingAssistant
Employee

Association Relationships
If two classes in a model need to communicate with each
other, there must be link between them.
An association denotes that link.
StudentInstructor
instructs
Here , an association is instructs.

Association Relationships(Cont’d)
The example indicates that a Student has one or
more Instructors:
InstructorStudent
1..*

Association Relationships (Cont’d)
The example indicates that every Instructor has
one or more Students:
InstructorStudent
1..*

UML Diagram Types with Examples
There are 14 UML diagram types to help you model these
behavior. They can be divided into two main categories
structure diagrams and behavioral diagrams
Class Diagram
Component Diagram
Deployment Diagram
Object Diagram
Package Diagram
Profile Diagram
Composite Structure Diagram
Use Case Diagram
Activity Diagram
State Machine Diagram
Sequence Diagram
Communication Diagram
Interaction Overview
Diagram
Timing Diagram

Structure diagrams show the things in a system
being modeled. In a more technical term they show
different objects in a system.
Behavioral diagrams shows what should happen
in a system. They describe how the objects interact
with each other to create a functioning system.

http://creately.com/blog/diagrams/uml-diagram-types-examples/

Class Diagram
Class diagrams are the most used UML diagram type. It is the
main building block of any object oriented solution. It shows
the classes in a system, attributes and operations of each class
and the relationship between each class.
In most modeling tools a class has three parts, name at the
top, attributes in the middle and operations or methods at
the bottom.
In large systems with many related classes, classes are
grouped together to create class diagrams. Different
relationships between classes are shown by different types of
arrows.

Component Diagram
A component diagram displays the structural relationship of
components of a software system.
These are mostly used when working with complex systems
that has many components.
Components communicate with each other using interfaces.
The interfaces are linked using connectors.

Simple Component Diagram with Interfaces

Object Diagram
Object Diagrams, sometimes referred as Instance diagrams
are very similar to class diagrams.
As class diagrams they also show the relationship between
objects but they use real world examples.
They are used to show how a system will look like at a
given time. Because there is data available in the objects
they are often used to explain complex relationships
between objects.

Use Case Diagram
Most known diagram type of the behavioral UML diagrams,
Use case diagrams gives a graphic overview of the actors
involved in a system, different functions needed by those
actors and how these different functions are interacted.
It’s a great starting point for any project discussion because
you can easily identify the main actors involved and the
main processes of the system.

Use Case diagram showing Actors and main processes

Activity Diagram
Activity diagrams represent workflows in an graphical way.
They can be used to describe business workflow or the
operational workflow of any component in a system.
Sometimes activity diagrams are used as an alternative to
State machine diagrams.

Activity Diagrams with start, end, processes and decision points

Sequence Diagram
Sequence diagrams in UML shows how object interact with
each other and the order those interactions occur.
It’s important to note that they show the interactions for a
particular scenario.
The processes are represented vertically and interactions are
show as arrows..

Sequence Diagrams in UML shows the interaction between two processes

Communication Diagram
Communication diagram was called collaboration diagram.
It is similar to sequence diagrams but the focus is on
messages passed between objects.
The same information can be represented using a sequence
diagram and different objects.

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