PhD Core Paper Unit 5 _Part 1 Software Design and UML Use Case Modeling.pdf

Ph.D – Core Paper
Computer Science and
Engineering (May 2022 Batch)
Unit 5: Software Design and
UML Use Case Modeling

Course Specification
Ph.D – CORE Paper
Computer Science and Engineering (May 2021 Batch)
Total Hours: 60 Credits: 4
UNIT 5_ PART 1: SOFTWARE DESIGN AND UML USE CASE
MODELING ( 10 HOURS )
2
By
Dr. M.K. Jayanthi Kannan, M.E.,MS.,MBA., M.Phil.,Ph.D.,
Professor,
Faculty of Engineering & Technology,
JAIN Deemed To-Be University,
Bengaluru.
Staff Room: 324- 8.
Office Hours : 8.30 AM -4 PM
Department of Computer Science
and Engineering,
FET Block.

UNIT 5: SOFTWARE DESIGN AND UML USE CASE MODELING
Syllabus :
 UML Modeling Concepts, Types of UML Diagrams with
Examples; User-Centered Design, Characteristics of Users,
Developing Use - Case Models of Systems, Use-Case
Diagram, Use- Case Descriptions,
 Basics of User Interface Design, Usability Principles, User
Interfaces Process of Design, Principles Leading to Good
Design, Techniques for Making Good Design Decisions,
Good Design Document;
 Pattern Introduction, Design Patterns: Abstraction-
Occurrence Pattern, General Hierarchical Pattern, Play-
Role Pattern, Singleton Pattern, Observer Pattern,
Delegation Pattern, Adaptor Pattern, Façade Pattern,
Immutable Pattern, Read-Only Interface Pattern and The
Proxy Pattern;
 Software Architecture Contents of Architecture Model,
Architectural Patterns: Multilayer, Client-Server, Broker,
Transaction Processing, Pipe & Filter and MVC
Architectural Patterns.
3

UNIT 5_PART 1 : TOPICS
 INTRODUCTION TO UML & MODELLING CONCEPTS
 TYPES OF UML DIAGRAMS WITH EXAMPLES
 USER-CENTERED DESIGN
 CHARACTERISTICS OF UML
 DEVELOPING USE-CASE MODELS
 USE-CASE DIAGRAMS
 USE-CASE DESCRIPTIONS
 BASICS OF USER INTERFACE DESIGN
 USABILITY PRINCIPLES & USER INTERFACES
4

o At the end of the 1980’s and the beginning of 1990’s, the first
Object-Oriented Development processes appeared.
• - Booch, Jacobson, Yourden, Rumbaugh
o In 1994, ‘Rumbaugh’ & ‘Booch’ decided to merge two important
methodologists & their approaches.
• They worked together at the Rational Software Corporation.
o In 1995, another methodologist, ‘Jacobson’, joined ‘Rumbaugh’
to the team his work focused on use cases.
o In 1997, the Object Management Group (OMG) started the
process of UML standardization.
o UML V2.0 is current version. 6
INTRODUCTION TO UML – Brief History

UML – Unified Modelling Language
The Unified Modelling Language is a standard graphical
language for modelling object oriented software.
UML is a standard language for specifying, visualizing,
constructing, and documenting the artifacts of software
systems.
UML is different from the other common programming
languages such as C++, Java, COBOL, etc.
UML is a pictorial language used to make software blueprints.
UML can be described as a general purpose visual modeling
language to visualize, specify, construct, and document
software system.
What's UML and Why Do You Need It?
https://www.youtube.com/watch?v=8CBnAmYnwk0 7
WHAT IS UML?

9
 UML is a modelling language to express and design
documents, software:
- Particularly useful for OO Design
- Not a process, but some have been proposed using UML
- Independent of implementation language.
WHAT IS UML? (Contd.)
 Language can be used from general initial design to very
specific detailed design across the entire software development
lifecycle.
 Open Standard, Graphical notation for specifying, visualizing,
constructing, and documenting the artifacts of software
systems.
 Support for diverse application areas.
 Based open experience and needs of the user community.
WHY USE UML?

10
Basic Building Blocks of UML
UML for Designers_ Keynote Speech by Dr.M.K.Jayanthi Kannan

 A Model is an abstraction describing a subset of a system.
 A View depicts selected aspects of a model.
 A Notation is a set of graphical or textural rules for depicting
views.
 Views & Models of a single system overlap each other.
 Example:
 System: Aircraft
 Models: Flight Simulator, Scale Model
 Views: All blueprints, Electrical wiring, Fuel system.
14
Systems, Models & Views

15
Systems, Models & Views
 Example - System: Aircraft

 The below shows different model, view & diagrams:
16
Models, Views & Diagrams

 Use Case
 Capture Requirements
 Domain Model
 Capture Process, Key Classes
 Design Model
 Capture details & behaviour of use cases & domain
objects.
 Add classes that do the work & define the architecture.
17
BASIC MODELLING STEPS

19
 The building blocks of UML can be defined as:
(1) Things
(2) Relationships
(3) UML Diagrams
(1) Things: are the most important building blocks of UML.
Things can be:
(i) Structural Things
(ii) Behavioral Things
(iii) Grouping Things
(iv) Annotational Things
UML MODELLING CONCEPTS

(i) Structural Things - define the static part of the model. They
represent the physical and conceptual elements.
(a) Class − Class represents a set of objects having similar responsibilities.
(b) Interface − Interface defines a set of operations, which specify the
responsibility of a class.
(c) Collaboration −Collaboration defines an interaction between elements.
(d) Use case −Use case represents a set of actions performed by a system for
a specific goal.
(e) Component −Component describes the physical part of a system.
(f) Node − A node can be defined as a physical element that exists at run
time.
20
UML MODELLING CONCEPTS (Contd.)
Class Interface Collaboration Use case
Component
Node

(ii) Behavioral Things: consists of the dynamic parts of UML
models. Following are the behavioral things:
(a) Interaction − Interaction is defined as a behavior that consists of a group of
messages exchanged among elements to accomplish a specific task.
(b) State machine − State machine is useful when the state of an object in its
life cycle is important. It defines the sequence of states an object goes through
in response to events. Events are external factors responsible for state
change.
(iii) Grouping Things: can be defined as a mechanism to group
elements of a UML model together. There is only one grouping thing
available:
(a) Package − Package is the only one grouping thing available for gathering
structural and behavioral things.
21

(iv) Annotational Things: can be defined as a mechanism to
capture remarks, descriptions, and comments of UML model
elements.
(a) Note - It is the only one Annotational thing available. A note is used
to render comments, constraints, etc. of an UML element.
(2) Relationships: is another most important building block of UML.
It shows how the elements are associated with each other and this
association describes the functionality of an application. There are
four kinds of relationships available:
(i) Dependency
(ii) Association
(iii) Generalization
(iv) Realization
22

(i) Dependency : Dependency is a relationship between two things in
which change in one element also affects the other.
(ii) Association: Association is basically a set of links that connects the
elements of a UML model. It also describes how many objects are taking part
in that relationship.
(iii) Generalization: Generalization can be defined as a relationship
which connects a specialized element with a generalized element. It basically
describes the inheritance relationship in the world of objects.
(iv) Realization: Realization can be defined as a relationship in which two
elements are connected. One element describes some responsibility, which is
not implemented and the other one implements them. This relationship
exists in case of interfaces.
23

(3) UML Diagrams
 UML diagrams are the ultimate output of the entire
discussion. All the elements, relationships are used to make a
complete UML diagram and the diagram represents a system.
 The visual effect of the UML diagram is the most important
part of the entire process. All the other elements are used to
make it complete.
 UML includes the following :
 Class diagram
 Object diagram
 Use case diagram
 Sequence diagram
 Collaboration diagram
 Activity diagram
 Statechart diagram
 Deployment diagram
 Component diagram
25

26
UML for Designers_ Keynote Speech by

TYPES OF UML DIAGRAMS
WITH EXAMPLES
28
https://www.youtube.com/watch?v=Yt8XkYIdhVU

29
UML DIAGRAMS
(a) Class diagrams:
 describe classes and their relationships
(b) Interaction diagrams:
 show the behaviour of systems in terms of how objects
interact with each other
 interactive behavior is represented in UML by two diagrams
known as Sequence diagram and Collaboration
diagram.
(c) State diagrams and activity diagrams:
 show how systems behave internally
(d) Component and deployment diagrams:
 show how the various components of systems are arranged
logically and physically

(a) Class diagrams: Example of an Customer Order
Management System
32
UML DIAGRAMS (Contd.)

(b) Interaction diagrams: Sequence Diagram -
Example of an Customer Order Management System
33

34
(b) Interaction diagrams: Communication Diagram -
Example of an Customer Order Management System

(c) State diagrams: Example of an Customer Order
Management System
35

36
(c) Activity diagrams: Example of an Customer Order
Management System

(d) Component diagrams: Example of an Customer
Order Management System
37

(d) Deployment diagrams: Example of an Customer
Order Management System
38

 User-centered design is an iterative process that focuses on an
understanding of the users and their context in all stages of
design and development.
 Each iteration of the UCD approach involves four distinct
phases:
(a) Understand the context
(b) Identify & specify user requirements
(c) Design phase
(d) Evaluation phase
40
USER-CENTERED DESIGN (UCD)

42
UML CHARACTERISTICS
o The Characteristics of UML is:
 It has detailed semantics
 It has extension mechanisms
 It has an associated textual language
Object Constraint Language (OCL)
The objective of UML is:
 To assist in software development
It is not a methodology

DEVELOPING USE-CASE MODELS
OF SYSTEMS
43

 A use-case is a typical sequence of actions that a user
performs in order to complete a given task.
 The objective of use-case analysis is to model the system from
the point of view of:
 how users interact with this system.
 when trying to achieve their objectives.
It is one of the key activities in requirements analysis
o A use-case model consists of:
 a set of use-cases.
 an optional description or diagram indicating how they
are related.
44
Use-Cases: Describing how the user will use the system

 A use-case should:
 Cover the full sequence of steps from the beginning of a
task until the end.
 Describe the user’s interaction with the system ...
 Not the computations the system performs.
 Be written so as to be as independent as possible from any
particular user interface design.
 Only include actions in which the actor interacts with the
computer.
 Not actions a user does manually
45
Use-Cases (Contd.)

46
SCENARIOS
 A scenario is an instance of a use case
 A specific occurrence of the use case
 a specific actor ...
 at a specific time ...
 with specific data.

How to describe a single use case:
A. Name: Give a short, descriptive name to the use case.
B. Actors: List the actors who can perform this use case.
C. Goals: Explain what the actor or actors are trying to achieve.
D. Preconditions: State of the system before the use case.
E. Summary: Give a short informal description.
F. Related use cases.
G. Steps: Describe each step using a 2-column format.
H. Postconditions: State of the system in following completion.
A and G are the most important.
47
Use-Cases (Contd.)

USE-CASE DIAGRAMS
&
USE-CASE DESCRIPTIONS
48

49
Use-Cases Representation & Symbols

 Example 1: SCHOOL LOGIN SYSTEM
50
USE-CASE DIAGRAMS (Example-1)

 Example 2: STUDENT ADMISSION PROCESS
51
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USE-CASE DIAGRAMS (Example-2)

Use case: Open file by browsing
Related use cases:
Specialization of: Open file
Includes: Browse for file
Steps:
Actor actions System responses
1. Choose ‘Open…’ command 2. File open dialog appears
3. Browse for file
4. Confirm selection 5. Dialog disappears
DESCRIPTION OF A USE-CASE (Contd.)
52

BASICS OF USER INTERFACE DESIGN
USABILITY PRINCIPLES & USER
INTERFACES
54

55
BASICS OF USER-INTERFACE DESIGN,
USABILITY PRINCIPLES, USER INTERFACES
 Everything depends on fully knowing your users, including
understanding their goals, skills, preferences, and their
tendencies.
 This is important as once you know your user its make it easier
to choose the right interface elements as listed below:
 First keep the interface simple.
 Be sure to create consistency and use the common UI
elements that are expected.
 Choose your page layout carefully.
 Always display the defaults.
 Visibility of system status.
 Match between system and the real world.
 Consistency and standards .
 Error prevention.
 Flexibility and efficiency of use .

Unit 4_Part 1 : Summary
So far in this Unit 5 _Part 1, we discussed the following concepts..
 INTRODUCTION TO UML & MODELLING CONCEPTS
 TYPES OF UML DIAGRAMS WITH EXAMPLES
 USER-CENTERED DESIGN
 CHARACTERISTICS OF UML
 DEVELOPING USE-CASE MODELS
 USE-CASE DIAGRAMS
 USE-CASE DESCRIPTIONS
 BASICS OF USER INTERFACE DESIGN
 USABILITY PRINCIPLES & USER INTERFACES 56

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