SE 4 : Waterfall Model in Software Engineering | Complete Explanation
Summary
TLDRIn this session, Rishali delves into the Waterfall Model, a linear, sequential software development lifecycle model introduced by Winston Royce in 1970. The model, comprising six phases from requirement analysis to maintenance, is ideal for projects with fixed requirements and is simple to understand. However, its rigidity, lack of flexibility, and inability to incorporate client feedback throughout the process are major drawbacks, making it unsuitable for complex or long-term projects. The session also highlights the model's advantages and disadvantages, setting the stage for discussions on alternative models in future sessions.
Takeaways
- 📚 The previous session covered the Software Development Life Cycle (SDLC) with real-life examples and an overview of the generic process model.
- 💧 Today's session focuses on the Waterfall model, the first and a widely used software development model, introduced by Winston Royce in 1970.
- 🔄 The Waterfall model is also known as the linear sequential development model, where each phase must be completed before the next one begins.
- 🔍 The model consists of six phases: requirement analysis, design, development, testing, deployment, and maintenance.
- ⚠️ The Waterfall model is best used when customer requirements are fixed and well-understood, making it ideal for short and simple projects.
- 📝 During the requirement analysis phase, all requirements are gathered, documented, and maintained in the Software Requirement Specification (SRS).
- 🎨 In the design phase, the gathered requirements are converted into high-level and low-level designs, which are then documented in the Software Design Document (SDD).
- 💻 The development phase involves converting the design into source code, developing the project module by module, followed by unit testing.
- 🛠️ In the testing phase, testers check if the software meets the customer requirements and perform integration testing to ensure functionality.
- 🚀 Deployment involves releasing the software to the market or delivering it to the customer, followed by maintenance to fix any issues or enhance the product.
Q & A
What is the waterfall model in software development?
-The waterfall model is a linear and sequential software development lifecycle model introduced by Winston Royce in 1970. It is characterized by its distinct phases, each of which must be completed before the next can begin, working only in a forward direction.
How many phases are there in the waterfall model?
-There are six phases in the waterfall model: requirement analysis and planning, design, development, testing, deployment, and maintenance.
What is the significance of the term 'waterfall' in the context of this model?
-The term 'waterfall' comes from the cascading components in the model's diagrammatic representation, which resemble a waterfall, indicating the sequential flow of the phases.
When is the waterfall model most suitable for use?
-The waterfall model is most suitable for use when customer requirements are fixed and not subject to change, typically in short and simple projects where tools and technologies are predefined and resources are readily available.
What is the first phase of the waterfall model and what does it involve?
-The first phase of the waterfall model is requirement analysis and planning, which involves communication between the customer, development team, and stakeholders to gather and document all the functional and non-functional requirements in a Software Requirement Specification (SRS) document.
What are the two types of design phases in the waterfall model?
-The two types of design phases in the waterfall model are high-level design, which includes the overall software architecture and algorithms, and low-level design, which includes user interface components and detailed design documentation.
What is the purpose of the SRS document in the waterfall model?
-The SRS document serves as a detailed description of the customer's requirements and serves as a contract between the development team and the customer, outlining exactly what the customer wants and needs from the software.
What is the role of the development phase in the waterfall model?
-In the development phase, the design is converted into source code using chosen programming languages and databases. Developers create the software module by module and perform unit testing to ensure each module functions correctly.
What are the main disadvantages of the waterfall model?
-The main disadvantages of the waterfall model include its inflexibility due to fixed requirements, the inability to go back to previous phases once moved forward, and its unsuitability for complex and long-term projects. Additionally, it does not allow for client feedback until after the complete software product is delivered.
What is the deployment and maintenance phase in the waterfall model?
-The deployment and maintenance phase is the final phase where the completed software product is released to the market or delivered to the customer. Any issues that arise after delivery are addressed in this phase, and if the customer requests new features, the product is enhanced accordingly.
Why is the waterfall model not recommended for complex projects?
-The waterfall model is not recommended for complex projects because it lacks the flexibility to accommodate changes and feedback throughout the development process. Errors made in early phases can propagate through the model, leading to significant risks and uncertainties in the final product.
Outlines
💧 Introduction to the Waterfall Model
The paragraph introduces the topic of the waterfall model in software development. It is highlighted as the first model to be discussed after the general software development life cycle. The waterfall model, introduced by Winston Royce in 1970, is a linear and sequential development model. It consists of six phases: requirement analysis and planning, design, development, testing, deployment, and maintenance. The model is characterized by its forward movement, where each phase must be completed before the next can begin. It is particularly suitable for projects with fixed customer requirements and is not ideal for complex or large-scale projects. The paragraph also explains the importance of the Software Requirement Specification (SRS) document, which acts as a contract between the development team and the customer.
🔍 Detailed Phases and Considerations of the Waterfall Model
This paragraph delves into the specific phases of the waterfall model, starting with requirement analysis where communication between stakeholders is crucial. It emphasizes the creation of the Software Requirement Specification (SRS) document that outlines the customer's needs. The design phase is next, which is divided into high-level design (including software architecture, algorithms, and database design) and low-level design (focusing on user interface components). The software design document (SDD) is created to document these designs. The paragraph also covers the development phase, where the design is converted into source code, and unit testing is performed. The testing phase involves comprehensive testing to ensure the software meets customer requirements, and the final phase, deployment and maintenance, covers releasing the software to the market and addressing any post-deployment issues.
📉 Advantages and Limitations of the Waterfall Model
The final paragraph discusses the advantages and disadvantages of the waterfall model. The model's simplicity and the requirement for each phase to be completed before moving forward are highlighted as benefits, making it suitable for small projects with fixed requirements. However, the model's inflexibility is a significant drawback, as it does not accommodate changes in requirements easily. Errors in early phases can lead to significant issues later on, and the model is not conducive to client feedback throughout the development process. The paragraph concludes by mentioning that iterative models, such as the spiral model, were developed to address these limitations and will be discussed in future sessions.
Mindmap
Keywords
💡Waterfall Model
💡Software Development Life Cycle (SDLC)
💡Requirement Analysis
💡Design Phase
💡Development Phase
💡Testing Phase
💡Deployment and Maintenance
💡Linear Sequential Development Model
💡Advantages
💡Disadvantages
💡Iterative Models
Highlights
Introduction to the Waterfall model as the first software development lifecycle model widely used in different projects.
The Waterfall model was introduced by Winston Royce in 1970 and is also known as the linear sequential development model.
The Waterfall model is called so because of its sequential phases, resembling a waterfall cascading downwards.
The model includes six phases: requirement analysis and planning, design, development, testing, deployment, and maintenance.
The Waterfall model works only in a forward direction, meaning each phase must be completed before the next one begins.
The model is best used when customer requirements are fixed and not expected to change.
It is not ideal for complicated and large projects; it is more suitable for short and simple projects.
Requirement analysis involves communication between customers and stakeholders to gather all functional and performance requirements.
The design phase converts gathered requirements into suitable designs, including high-level and low-level designs.
In the development phase, software design is converted into source code, and developers create the project module-wise.
The testing phase ensures that the software meets customer requirements through various testing methods.
Deployment and maintenance involve releasing the software to the market and providing support for any issues or enhancements.
Advantages of the Waterfall model include its simplicity and the clear documentation of each phase.
Disadvantages include its inflexibility, high risk, and unsuitability for complex or long-term projects due to the inability to go back to previous phases.
The model does not allow for client feedback during each phase, which can lead to dissatisfaction with the final product.
Transcripts
good evening everyone this is rishali in
previous session we discuss about
software development life cycle with
real life examples and generic process
model I have mentioned complete software
engineering subject playlist Link in
below description box now in today's
session we will discuss about the next
important and first model that is
waterfall model let's start the session
in today's session we will discuss about
introduction then when to use waterfall
model their phases and advantages and
disadvantages of waterfall model let's
see all these points one by one next
now the first thing is what exactly
waterfall model see waterfall model
introduced by Winston Royce in 1970.
waterfall model also called as linear
sequential development model in your
exam they will ask either explain
waterfall model or explain linear
sequential development model the answer
is same
see here this is a structure of
waterfall model
waterfall model is a first software
development lifecycle model which is
widely used in different software
engineering projects as per the customer
requirements
now in this waterfall model there are
total six phases like requirement
analysis and planning then design
development testing deployment and
maintenance
this model is called as waterfall
because see here their diagrammatic
representation every cascading
components show the waterfalls that's
why this is called as waterfall model
now the main aim of waterfall model is
here in this model every phase is
completed before the next phase can
begin means first requirement analysis
phase this phase completed then they
send output to the design phase now
design phase take a input of this
and this will send output to the
development phase now development phase
completed and send output to the testing
phase means this waterfall model work
only in forward Direction not a backward
Direction This is a main concept of
waterfall model next
now when to use waterfall model as we
know in software engineering there are
lots of and different models every model
having their own requirements
so waterfall model mainly used in when
customer requirement is fixed not
changed only that way this waterfall
model will work now waterfall model is
not used in complicated and big project
it is used in short project and simple
project in waterfall model all the tools
and technology used in consistent means
that is predefined you can't change
these tools and technology in ongoing
performance of waterfall model
now waterfall model also having all the
resources are well prepared and easily
available so only that way mainly
requirements are fixed and used for
short and simple project clear next
now these are the some phases of
waterfall model the first phase is
requirement analysis
every software project always start with
the communication the communication
between the customer and development
team or communication between customers
and stakeholders stakeholder means each
and every person involved in particular
software project whether it is customer
clients tester project manager then
developer so each and every person
involved in software project which is
called as stakeholders so in requirement
analysis there is a communication
between them
so they discuss what exactly customer
want and what is the need of the
customer means they gather all the
requirements from the customer which
includes functional requirements means
Suppose there is a online shopping
application so functional requirements
means what is the models will be
included in particular software what
will be the features and specification
about software then performance Miss
accuracy and portability about software
and interfacing means their graphical
user front-end interface so this all
requirements have collected in this
particular phase after collecting
requirements these requirements maintain
in particular document this document are
called as SRS that is software
requirement specification this document
having detailed description of what
exactly customer mode and requirements
of the customer basically this SRS
document is a contract between
development team and the customer
now next
so after requirement analysis there is a
design phase this SRS document sent
forward to the design phase design phase
handled by the UI ux designer team so
all the gather requirements are
converted into the suitable design
so this design are divided into the two
parts like high level design and low
level design so high level design
include complete software architecture
means how your project or how your
products looks like in future so which
includes algorithm like step by solution
for example there is a sign up and login
page so when you click on login which
page will be open so this all design can
be drawn in this design phase so which
includes algorithm flowcharts then
decision tree database design which kind
of database tables have included then
low level design includes user interface
components where is a text box checkbox
have present then rough paper design so
all these things have design in this
design phase and documented into the
software design document that is sdd now
this previous phase SRS and sdd sent
forward to the next phase
in this phase also they discuss and
finalize which programming languages
have used in this particular software
project which database and other
hardware and software requirements have
used this all things have discussed in
this particular phase
let's see here in this diagram this is a
flowchart where is the start where is
the end of the project this is a GUI
where is a button text box have present
and this is a complete software
architecture in this way they draw the
design by using particular software next
now the next one is a development phase
so after designing development phases
there so development phase means your
software design is directly converted
into the source code or programming
languages so here developer decide the
programming languages and database and
they first develop a module wise
software for example in your project in
your software there is a login module
sign up module then a shopping cart
model so they develop a complete project
module wise and after developing they
perform the unit testing here unit
testing means one by one they check the
model whether it is properly developed
or not so complete programming part done
here next
now next one is the testing phase so in
testing phase tester perform all the
testing activities
and check that whether the particular
software meet the customer requirements
or not
tests are mainly perform integration
testing here they test complete software
at the same time whether it is
particularly work or not if there are
any errors they report those error and
maintain test cases and test reports
next
now the last phase is deployment and
maintenance phase here after completing
complete software product this software
product is released in Market or
delivered to the customer this is called
as deployment and after delivering if
there are any issue have occurred so
this thing is called as maintenance so
there are some support managers who fix
those issues and enhance the product
version if customer want any new
features they enhance the customer
product
so these all things have included in
maintenance phase
now what was the advantages of waterfall
model see we already discussed all these
phases in detail previously and in this
session so what exactly advantages of
waterfall model first it is very simple
and easy to understand the next thing is
each phase must be completed see
waterfall model going to only forward
Direction not a backward Direction first
you need to perform requirement analysis
then design then implementation in this
way
they can't go backward and again change
the requirement here requirements are
fixed
so it works very well in small project
and requirements are fixed and
understood right so here all the process
and results all the things have
documented properly clear next
now main thing is what was the
disadvantages of waterfall model in
disadvantages of disadvantages of
waterfall model here requirements are
fixed this is the main disadvantages
because if customer wants some new
features so they can't edit those
feature in waterfall model that's why
there is a high amount of risk and
uncertainty
next thing is if errors can be occur
suppose in requirement analysis errors
can be occurred that will be solved in
the particular phase only you can't go
in backward Direction suppose in coding
phase you you want to change a design so
you can't go backward in design phase
right so this is the main disadvantages
this is not a flexible model okay and uh
also the next thing is it is not a good
model for complex and long going project
and client valuable feedback cannot be
included here after completing complete
software product only after that client
Val feedback will be taken basically
client feedback taken on each and every
phase so this thing is not included in
waterfall model clear
so by solving all these disadvantages
the next spiral model iterative models
have been there so we will discuss this
model in next sessions
so this is all about waterfall model
keep learning thank you
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