This document provides an overview of various software development life cycle (SDLC) models including waterfall, V-shape, prototyping, spiral, iterative, and incremental models. It describes the key stages and characteristics of each model as well as discussing their advantages and disadvantages. The document is intended to teach students about software engineering processes and which models are suited to different types of projects.

1. Amity School of Engineering & Technology (CSE)
AMITY SCHOOL OF ENGINEERING & TECHNOLOGY
Bachelor of Technology (CSE), Semester-VI
Software Engineering(IT 301)
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Prepared By: Dr. Rakesh Garg

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Learning Objectives
• To make the students to develop skills that will enable
them to construct software of high quality – software
that is reliable, and that is reasonably easy to
understand, modify and maintain.
• To make student learn how to use available resources
to develop software, reduce cost of software and how
to maintain quality of software.

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Contents to be Covered
 Software Development Life Cycle [SDLC]
Waterfall Model
V-Shape Model
Prototyping and Evolutionary Model
Spiral Model
Iterative and Incremental Model

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SDLC
Know
n
as
Software
developme
nt
methodolo
gy
System
developmen
t
methodolog
y
Software
developmen
t life cycle
Software
developme
nt process
Softwar
e
proces
s
A framework that describes
the activities performed at
each stage of a software
development project.
SDLC is a splitting of software
development work into distinct
phases (or stages) containing
activities with the intent of
better planning and
management
The SDLC aims to produce a high
quality software that meets or
exceeds customer expectations,
reaches completion within times
and cost estimates

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Waterfall Model
Operation
and
maintenanc
e
Release
and
deploymen
t
Testing
Implementat
i
on
Design
Requirement
s analysis
The usage
Projects which not focus on changing requirements, for example, responses
for request for proposals (RFPs)
A linear
sequential flow.
Oldest and most well-known - 1970

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Waterfall Model (Contd…)
• The waterfall Model is a linear sequential flow.
• In which progress is seen as flowing steadily downwards (like a
waterfall) through the phases of software implementation.
• This means that any phase in the development process begins only if
the previous phase is complete.
• The waterfall approach does not define the process to go back to the
previous phase to handle changes in requirement.
• The waterfall approach is the earliest approach that was used for
software development.

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Waterfall Model (Contd…)
Advantages Disadvantages
Easy to be explained inflexible, like the waterfall model
Stages and activities are well defined Adjusting scope is difficult and
expensive
Milestones are well understood Model doesn't provide a clear path
for problems
found during testing phases
Each phase has specific deliverables Costly and required more time
Works well for smaller projects
where requirements are very well
understood.
Needs very proper and detailed
planning
Process and results are well
documented
No continuous customer
involvement to review the output

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V-Shape Model
The usage
·Software requirements
clearly defined and
known.
·Software development
technologies and tools is
well-known.

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V-Shape Model (Contd…)
• It is an extension for waterfall model, Instead of moving down in a
linear way, the process steps are bent upwards after the coding
phase, to form the typical V shape.
• The major difference between V-shaped model and waterfall model
is the early test planning in V-shaped model.

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V-Shape Model (Contd…)
Advantages Disadvantages
Verification and validation of the product
in early
stages of product development
Assumes that the requirements of a
system can be
frozen and known from beginning
Easy to use.
Stages and activities are well defined
Does not easily handle dynamic
changes in requirements
Higher chance of success over the
waterfall model due to the
development of test plans early on
during the life cycle
Inflexible and adjusting scope is difficult
and
expensive
Each phase has specific deliverables Costly and required more time
Works well for where
requirements are easily
understood
Needs very proper and detailed planning
No continuous customer involvement

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Prototyping Model
The usage
·This process can be used
with any software
developing life cycle
model.
·While this shall be focused
with systems needs more
user interactions.
·So, the system do not have
user interactions, such as,
system does some
calculations shall not have
prototypes.
Increment
al
prototypin
g
Extreme
prototypin
g
Evolutionar
y
prototyping
Throwawa
y
prototypin
g

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Prototyping Model (Contd…)

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Prototyping Model (Contd…)
• It refers to the activity of creating prototypes of software
applications, for example, incomplete versions of the software
program being developed.
• It is an activity that can occur in software development. It used to
visualize some component of the software to limit the gap of
misunderstanding the customer requirements by the development
team.
• This also will reduce the iterations may occur in waterfall approach
and hard to be implemented due to inflexibility of the waterfall
approach.
• So, when the final prototype is developed, the requirement is
considered to be frozen.

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Prototyping Model (Contd…)
Throw-Out
Prototyping

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Prototyping Model (Contd…)
Evolutionary
Prototyping
In evolutionary prototyping, the concept of the system will be developed
as the project progresses. First of all, we will develop the most visual
aspect of the system. You present a portion of the system to the customer
and continue to develop prototypes based on the feedback received. At
some point, you and the customer agree that the prototype is “good
enough” and release the prototype as the final product.

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Prototyping Model (Contd…)
Advantages Disadvantages
Reduced time and costs Insufficient analysis, guess why?
This can be disadvantage if the
developer loses time in developing the
prototypes
User confusion of prototype and
finished system
Improved user involvement Developer misunderstanding of user
objectives·
Users give corrective feedback Excessive development time of the
prototype
A more accurate end product Expense of implementing
prototyping, this can be eliminated if
it will be integrated with the final
product. Process may continue
forever (scope creep)

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Spiral Model
The usage
• It is used in
shrink-wrap large
applications and
systems which
built-in small
phases or
segments.

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Spiral Model (Contd…)
• It is combining elements of both
design and prototyping-in-stages, in
an effort to combine advantages of
top-down and bottom-up concepts.
• This model of development combines
the features of the prototyping model
and the waterfall model.
• The spiral model is favored for
large, expensive, and
complicated projects.
• This model uses many of the same
phases as the waterfall model, in
essentially the same order, separated
by planning, risk assessment, and the
building of prototypes and
simulations.

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Spiral Model (Contd…)
• It is combining elements of both
design and prototyping-in-stages, in
an effort to combine advantages of
top-down and bottom-up concepts.
• This model of development combines
the features of the prototyping model
and the waterfall model.
• The spiral model is favored for
large, expensive, and
complicated projects.
• This model uses many of the same
phases as the waterfall model, in
essentially the same order, separated
by planning, risk assessment, and the
building of prototypes and
simulations.

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Spiral Model (Contd…)
Advantages Disadvantages
Estimates (i.e. budget, schedule, etc.)
become more realistic as work
progresses.
High cost and time to reach the final
product.
Changing requirements can be
accommodated.
Needs special skills to evaluate
the risks and assumptions.
Development can be divided into
smaller parts and more risky parts
can be developed earlier which helps
better risk management.
Highly customized limiting re-usability.
Users see the system early and
give corrective feedback.
Time spent planning, setting
objectives, doing risk analysis and
prototyping will be huge.
A more accurate end product.

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Iterative Model
The iterative model is a particular implementation of SDLC that focuses on an
initial, simplified implementation, which then progressively gains more complexity
and a broader feature set until the final system is complete. When discussing the
iterative method, the concept of incremental development will also often be used
liberally and interchangeably, which describes the incremental alterations made
during the design and implementation of each new iteration.

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Incremental Model
Incremental Model is a process of software development where requirements
divided into multiple standalone modules of the software development cycle. In this
model, each module goes through the requirements, design, implementation and
testing phases.

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