UML Diagrams

Detailed Presentation on UML
Akul Nigam(9911103424)
Devesh Vashishtha(9911103451)
Kartik Chaudhary(9911103477)
Ritvik Bhardwaj(9911103529)

Overview
• What is UML?
• Understanding the basics of UML
• Why UML?
• UML diagrams
• UML Modeling tools

What is UML?
• UML stands for “Unified Modeling Language”
• Modeling is describing system at a high level of
abstraction
• It is a industry-standard graphical language for
specifying, visualizing, constructing, and
documenting the artifacts of software systems
• The UML uses mostly graphical notations to express
the OO analysis and design of software projects.
• Simplifies the complex process of software design

Why UML for Modeling/Benefits of UML
• Use graphical notation to communicate more
clearly than natural language (imprecise) and
code(too detailed).
• Quick understanding
• Help acquire an overall view of a system.
• Lessens chances of conflicts.
• UML is not dependent on any one language or
technology.
• Necessary to manage complexity.
• UML moves us from fragmentation to
standardization.

Types of UML Diagrams
• Use Case Diagram
• Class Diagram
• Activity Diagram
• Sequence Diagram
• Collaboration Diagram
• State Diagram
• Deployment Diagram

Use Case Diagram
• Used for describing a set of user scenarios
• Illustrates functionality provided by the
system
• Mainly used for capturing user requirements
• Work like a contract between end user and
software developers

Use Case Diagram (core components)
Actors: A role that a user plays with respect to the system,including
human users and other systems. e.g.,inanimate physical objects (e.g. robot);
an external system that needs some information from the current system.
Use case: A set of scenarios that describing an interaction between a user
and a system, including alternatives.
System boundary: rectangle diagram representing the boundary
between the actors and the system.

Use Case Diagram(core relationship)
Association: communication between an actor and
a use case; Represented by a solid line.
Generalization: relationship between one general
use case and a special use case (used for defining
special alternatives)
Represented by a line with a triangular arrow head
toward the parent use case.

Use Case Diagram(core relationship)
Extend: a dotted line labeled <<extend>> with an arrow
toward the base case. The extending use case may add behavior to
the base use case. The base class declares “extension points”.
<<extend>>
Include: a dotted line labeled <<include>> beginning at base
use case and ending with an arrows pointing to the include
use case. The include relationship occurs when a chunk of
behavior is similar across more than one use case. Use
“include” in stead of copying the description of that behavior.
<<include>>

Use Case Diagrams
Library System
Borrow
Order Title
Fine Remittance
Client
Employee
Supervisor
• A generalized description of how a system will be used.
• Provides an overview of the intended functionality of the system
Boundary
Actor
Use Case

Use Case Diagrams(cont.)
•Pay Bill is a parent use case and Bill Insurance is the
child use case. (generalization)
•Both Make Appointment and Request Medication
include Check Patient Record as a subtask.(include)
•The extension point is written inside the base case
Pay bill; the extending class Defer payment adds the
behavior of this extension point. (extend)

Class diagram
• Used for describing structure and behavior in
the use cases
• Provide a conceptual model of the system in
terms of entities and their relationships
• Used for requirement capture, end-user
interaction
• Detailed class diagrams are used for
developers

Class representation
• Each class is represented by a rectangle subdivided into three
compartments
– Name
– Attributes
– Operations
• Modifiers are used to indicate visibility of attributes and operations.
– ‘+’ is used to denote Public visibility (everyone)
– ‘#’ is used to denote Protected visibility (friends and derived)
– ‘-’ is used to denote Private visibility (no one)
• By default, attributes are hidden and operations are visible.

An example of Class
Account_Name
- Customer_Name
- Balance
+addFunds( )
+withDraw( )
+transfer( )
Name
Attributes
Operations

OO Relationships
• There are two kinds of Relationships
– Generalization (parent-child relationship)
– Association (student enrolls in course)
• Associations can be further classified as
– Aggregation
– Composition

Subtype2
Supertype
Subtype1
OO Relationships: Generalization
- Generalization expresses a
parent/child relationship among related
classes.
- Used for abstracting details in several
layers
Regular
Customer
Loyalty
Customer
CustomerExample:
Regular
Customer
Loyalty
Customer
Customeror:

OO Relationships: Association
• Represent relationship between instances of
classes
– Student enrolls in a course
– Courses have students
– Courses have exams
– Etc.
• Association has two ends
– Role names (e.g. enrolls)
– Multiplicity (e.g. One course can have many students)
– Navigability (unidirectional, bidirectional)

Association: Multiplicity and Roles
University Person
1
0..1
*
*
Multiplicity
Symbol Meaning
1 One and only one
0..1 Zero or one
M..N From M to N (natural language)
* From zero to any positive integer
0..* From zero to any positive integer
1..* From one to any positive integer
teacheremployer
Role
Role
“A given university groups many people;
some act as students, others as teachers.
A given student belongs to a single
university; a given teacher may or may not
be working for the university at a particular
time.”
student

Association: Model to Implementation
Class Student {
Course enrolls[4];
}
Class Course {
Student have[];
}
Student Course
enrollshas
* 4

OO Relationships: Composition
Class W
Class P1 Class P2
Composition: expresses a relationship among instances
of related classes. It is a specific kind of Whole-Part
relationship.
It expresses a relationship where an instance of the
Whole-class has the responsibility to create and initialize
instances of each Part-class.
It may also be used to express a relationship where instances
of the Part-classes have privileged access or visibility to
certain attributes and/or behaviors defined by the
Whole-class.
Composition should also be used to express relationship where
instances of the Whole-class have exclusive access to and
control of instances of the Part-classes.
Composition should be used to express a relationship where
the behavior of Part instances is undefined without being
related to an instance of the Whole. And, conversely, the
behavior of the Whole is ill-defined or incomplete if one or
more of the Part instances are undefined.
Whole Class
Part Classes
Automobile
Engine Transmission
Example

OO Relationships: Aggregation
Class C
Class E1 Class E2
AGGREGATION
Aggregation: expresses a relationship among instances
of related classes. It is a specific kind of Container-
Containee
relationship.
It expresses a relationship where an instance of the
Container-class has the responsibility to hold and
maintain
instances of each Containee-class that have been created
outside the auspices of the Container-class.
Aggregation should be used to express a more informal
relationship than composition expresses. That is, it is an
appropriate relationship where the Container and its
Containees can be manipulated independently.
Aggregation is appropriate when Container and
Containees have no special access privileges to each other.
Container Class
Containee Classes
Bag
Apples Milk
Example

Aggregation vs. Composition
•CompositionComposition is really a strong form of aggregation
•components have only one owner
•components cannot exist independent of their owner
•components live or die with their owner
e.g. Each car has an engine that can not be shared with
other cars.
•Aggregations may form "part of" the aggregate, but may not
be essential to it. They may also exist independent of the
aggregate.
e.g. Apples may exist independent of the bag.

Class Diagram Example
Hotel Management System

Activity Diagram
• Procedural flow of control between two or more
class objects
• Activities are grouped into swim lanes.
• Activity is modeled by drawing a rectangle with
rounded edges, enclosing the activity's name.
• Connected to other activities through transition
lines
• Activities that terminate the modeled process are
connected to a termination point

Activity diagram, with
two swim lanes to
indicate control
of activity by two
objects: the band
manager, and the
reporting tool

Sequence Diagram
• Two dimensional
• Vertical dimension shows sequence of
messages in the time order that they occur.
• Horizontal dimension shows the object
instances to which the messages are sent.
• Self-Call can also be there in which a message
that an object sends to itself.

Sequence Diagram(make a phone call)
Caller Phone Recipient
Picks up
Dial tone
Dial
Ring notification Ring
Picks up
Hello

Sequence Diagrams – Object Life Spans
• Creation
– Create message
– Object life starts at that point
• Activation
– Symbolized by rectangular stripes
– Place on the lifeline where object is
activated.
– Rectangle also denotes when object
is deactivated.
• Deletion
– Placing an ‘X’ on lifeline
– Object’s life ends at that point
Activation bar
A
B
Create
X
Deletion
Return
Lifeline

Sequence Diagram
User Catalog Reservations
1: look up ()
2: title data ()
3: [not available] reserve title ()
4 : title returned ()
5: hold title ()
5 : title available ()
6 : borrow title ()
6 : remove reservation ()
Issuing a book from library

Collaboration Diagram
• Shows the relationship between objects
and the order of messages passed
between them.
• The objects are listed as rectangles and
arrows indicate the messages being
passed
• Convey the same information as
sequence diagrams, but focus on object
roles instead of the time sequence.

Collaboration diagrams of earlier made sequence diagram of issuing of book
from library
User
Catalog
Reservations
start
1: look up
2: title data
3 : [not available] reserve title
4 : title returned
5 : hold title
6 : borrow title
6: remove reservation
5: title available

State Diagrams
State Diagrams show the sequences of states an object goes through during
its life cycle in response to stimuli, together with its responses and actions;
an abstraction of all possible behaviors.
Unpaid
Start End
Paid
Invoice created paying Invoice destroying
(Billing Example)

Deployment Diagram
• System will be physically deployed in the
hardware environment
• System's production staff makes its
considerable use
• Purpose is to show where the different
components of the system will physically run
and how they will communicate with each
other

UML Modeling Tools
• Rational Rose (www.rational.com) by IBM
• TogetherSoft Control Center, Borland (
http://www.borland.com/together/index.html)
• ArgoUML (free software) (http://argouml.tigris.org/ )
OpenSource; written in javawritten in java
• Others (http://www.objectsbydesign.com/tools/umltools_byCompany.html )

UML Diagrams

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