SE 4 : Waterfall Model in Software Engineering | Complete Explanation

Summary

In 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

00:00

💧 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.

05:02

🔍 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.

10:02

📉 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.

Keywords

💡Waterfall Model

The Waterfall Model is a sequential software development process where each phase of development is completed before moving on to the next phase. It starts with a requirements analysis and ends with maintenance. The model is called 'waterfall' because of its cascading effect, where each phase flows into the next. In the video, the Waterfall Model is introduced as the first software development lifecycle model, emphasizing its linear and sequential nature.

💡Software Development Life Cycle (SDLC)

SDLC refers to the process of planning, creating, testing, and deploying an information system. It is a structured approach that includes a detailed set of project activities with beginning and end points, such as the Waterfall Model. The video discusses the Waterfall Model as an important and first model within the broader context of SDLC.

💡Requirement Analysis

Requirement Analysis is the first phase of the Waterfall Model where the development team communicates with the customer and stakeholders to understand and gather all the necessary requirements for the software project. It includes functional, performance, and interface requirements. In the video, it is highlighted as the starting point of the Waterfall Model, where the Software Requirement Specification (SRS) document is created.

💡Design Phase

The Design Phase follows the Requirement Analysis and involves creating a detailed plan for the system, including the architecture, algorithms, and user interface. It is divided into high-level and low-level design. The video explains that this phase is handled by UI/UX designers and results in the Software Design Document (SDD).

💡Development Phase

The Development Phase is where the design is converted into source code using chosen programming languages and databases. It involves module-wise development and unit testing to ensure each part of the software is functioning correctly. The video emphasizes that developers make decisions about technology and tools during this phase.

💡Testing Phase

The Testing Phase is where the software is rigorously tested to ensure it meets the customer's requirements. It includes various types of testing like integration testing to check the software's functionality as a whole. The video mentions that testers report any errors and maintain test cases and reports during this phase.

💡Deployment and Maintenance

Deployment is the phase where the completed software is released to the market or delivered to the customer. Maintenance follows, addressing any issues that arise post-deployment and possibly adding new features as requested by the customer. The video describes this as the final phase of the Waterfall Model, where the product is supported and enhanced.

💡Linear Sequential Development Model

This term is another name for the Waterfall Model, emphasizing its linear progression from one phase to the next without looping back. The video script mentions that this model is widely used in software engineering projects and is characterized by its forward-moving phases.

💡Advantages

The video discusses the advantages of the Waterfall Model, such as its simplicity and ease of understanding. It is also noted for its structured approach where each phase must be completed before the next can begin, which is beneficial for small projects with fixed requirements.

💡Disadvantages

The script highlights the disadvantages of the Waterfall Model, including its inflexibility and the inability to accommodate changes once a phase is completed. It also mentions that it is not suitable for complex or long-term projects and that client feedback is limited to the end of the process.

💡Iterative Models

The video concludes by mentioning that iterative models, such as the Spiral Model, were developed to address the limitations of the Waterfall Model. These models allow for more flexibility and client feedback throughout the development process, contrasting with the rigidity of the Waterfall Model.

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