Classic Waterfall model in Software Engineering

Summary

In this educational video, the classical waterfall model in software development is explained, highlighting its linear, sequential phases: feasibility study, requirement analysis, design, coding, testing, and maintenance. The video emphasizes its simplicity and suitability for small projects with fixed requirements. However, it also points out its rigidity, lack of flexibility, absence of parallelism, and high risk due to late feedback, often resulting in a significant maintenance phase where most issues are addressed.

Takeaways

• 😀 Classical Waterfall model was introduced in the 1970s and is a very old model.
• 😀 It is called a 'waterfall' because the steps are sequential, like a waterfall.
• 😀 The model includes phases such as feasibility study, requirement analysis, design, coding, testing, and maintenance.
• 😀 Feasibility study ensures the project is viable technically and financially.
• 😀 Maintenance is the most important phase as it requires around 60% of the effort.
• 😀 The Waterfall model is rigid; once a phase is completed, it cannot be revisited.
• 😀 It works well for small projects where the customer's requirements are clear and fixed.
• 😀 Lack of feedback between phases is a major disadvantage of the model.
• 😀 There is no parallelism, meaning one phase must be completed before the next can start.
• 😀 High risk is associated with the Waterfall model because issues are only identified in the final stages.

Q & A

What is the classical waterfall model?

The classical waterfall model is an old software development model from the 1970s, characterized by a linear and sequential approach where each phase must be completed before the next one begins.

Why is it called the 'waterfall' model?

It is called the 'waterfall' model because the phases in the process are depicted in a diagram that resembles a waterfall, flowing in a systematic way from one phase to the next without looping back.

What are the main phases of the classical waterfall model?

The main phases of the classical waterfall model include feasibility study, requirement analysis, specification design, coding and unit testing, system testing and integration, and maintenance.

What is the purpose of the feasibility study in the waterfall model?

The feasibility study determines whether a project is feasible, considering technical and financial aspects, ensuring that the project can be completed within the given budget and resources.

Why is the waterfall model considered rigid?

The waterfall model is considered rigid because it does not allow for changes once a phase is completed and the process moves to the next phase, lacking flexibility and feedback mechanisms.

What are the advantages of using the classical waterfall model?

The advantages of the classical waterfall model include its simplicity, systematic approach, and suitability for small projects with clear and fixed requirements.

What are the disadvantages of the classical waterfall model?

The disadvantages include its rigidity, lack of flexibility, absence of parallelism, high risk due to the late identification of issues, and the need for a significant amount of effort in the maintenance phase.

Why is the maintenance phase considered very important in the waterfall model?

The maintenance phase is crucial because it is where most of the effort (up to 60%) is spent fixing problems and bugs that were not identified in earlier phases due to the model's rigidity.

How does the waterfall model handle changes in requirements?

The waterfall model does not handle changes in requirements well, as it is designed to move forward through phases without looping back, making it difficult to incorporate changes after the initial requirements phase.

What is an example given in the script to illustrate the problems with the waterfall model?

The script uses the example of building a dream house where the customer does not see the progress until the end, leading to late discovery of issues like a small kitchen or misplaced bedroom, which then require costly and time-consuming changes during the maintenance phase.

Outlines

00:00

💻 Introduction to the Classical Waterfall Model

The video begins with an introduction to the Classical Waterfall Model, a traditional software development approach dating back to the 1970s. The presenter outlines the various phases of the model, including feasibility study, requirement analysis, specification design, coding and unit testing, system testing and integration, and maintenance. The video emphasizes the importance of each phase, using examples to illustrate the process. The presenter also discusses the model's advantages, such as its systematic and straightforward nature, which makes it suitable for small projects with clear and unchanging requirements. However, the rigidity of the model is highlighted as a significant disadvantage, as it lacks flexibility and does not accommodate feedback or changes once a phase is completed.

05:02

🚧 Disadvantages and Risks of the Classical Waterfall Model

In the second paragraph, the presenter delves into the disadvantages and risks associated with the Classical Waterfall Model. The rigidity of the model is critiqued for not allowing for changes or parallel work, which can lead to inefficiencies and idle resources. The lack of feedback and the inability to incorporate new experiments or ideas during the development process are also highlighted as major drawbacks. The presenter uses the analogy of building a dream house to illustrate the high risk and potential for costly mistakes when problems are only discovered in the final phase. The video concludes with a discussion on the significant effort and resources often required in the maintenance phase due to the model's inflexibility, which can lead to wasted time and additional costs.

Keywords

💡Classical Waterfall Model

The Classical Waterfall Model is a sequential design process used in software development, introduced in the 1970s. It is characterized by its linear and phased approach, where each phase must be completed before the next one begins. This model is foundational as it laid the groundwork for subsequent development methodologies. In the video, it is described as rigid and inflexible, which can be advantageous for small projects with clearly defined requirements but disadvantageous for larger, more complex projects that require adaptability.

💡Feasibility Study

A feasibility study is an essential initial phase in the Waterfall Model where the project's viability is assessed. This involves evaluating whether the project is technically and financially feasible, considering factors like available resources, budget constraints, and the required technology. The video script mentions that this phase is crucial for determining if the project can be completed within the given constraints, which is a critical decision point before proceeding with development.

💡Requirement Analysis

Requirement Analysis is the process of gathering and understanding the specific needs of the client or end-users. This phase is vital as it sets the foundation for the software's functionality and features. The video script emphasizes that after the feasibility study, developers engage in requirement analysis to understand what the customer needs, which then influences the project's specifications and design.

💡Specification Design

Specification Design refers to the phase where the software's detailed requirements are documented. This includes creating a Software Requirements Specification (SRS) document that outlines the functionality, performance, and constraints of the software. The video explains that this document serves as a contract between the developer and the customer, ensuring that all agreed-upon specifications are met.

💡Coding and Unit Testing

Coding is the phase where the software is actually written, and Unit Testing follows, where each module of the code is tested for correctness and reliability. The video script uses the term 'Coding and Unit Testing' to describe the implementation phase of the Waterfall Model, highlighting that after the design is finalized, developers write the code and then test each component to ensure it works as intended before integration.

💡System Testing and Integration

System Testing and Integration is the phase where individual modules are combined and tested as a whole to ensure they work together correctly. The video script explains that after unit testing, the modules are integrated, and system testing is conducted to identify any issues that arise from the combination of different parts of the software.

💡Maintenance

Maintenance is the final phase of the Waterfall Model where the software is supported and any bugs or issues are fixed after deployment. The video script points out that maintenance is a critical and often labor-intensive phase, as it can account for up to 60% of the total effort in a project. This phase is necessary to address any problems that were not caught during earlier testing stages.

💡Rigidity

Rigidity in the context of the Waterfall Model refers to its inflexibility once a phase is completed and the project moves to the next. The video script describes this as a disadvantage because it does not allow for feedback or changes once a phase is completed, which can lead to issues in later stages that are more costly and time-consuming to fix.

💡Parallelism

Parallelism, as discussed in the video, refers to the ability to work on multiple tasks or phases simultaneously. The Waterfall Model lacks parallelism because it is a linear process where one phase must be completed before the next can begin. This can lead to inefficiencies, as teams may be idle while waiting for the completion of a previous phase.

💡Risk

Risk in software development pertains to the potential for problems or failures. The video script highlights that the Waterfall Model carries high risk due to its rigidity and lack of flexibility. Since changes are not accommodated once a phase is complete, any issues that arise may not be discovered until the final stages, leading to significant rework and increased project risk.

💡Feedback System

A feedback system in software development allows for continuous improvement and adjustment throughout the development process. The video script argues that the Waterfall Model lacks an effective feedback system, which can lead to problems being identified late in the development cycle. This lack of feedback can result in costly and time-consuming fixes during the maintenance phase.

Highlights

Introduction to the classical waterfall model.

The classical waterfall model originated in the 1970s.

The model is often used for small projects due to its simplicity.

The waterfall model is visually represented as a series of steps, like a waterfall.

Phases of the waterfall model include feasibility study, requirement analysis, design, coding, testing, and maintenance.

Feasibility study determines if a project is technically and financially viable.

Requirement analysis and specification involve understanding and documenting customer needs.

Design phase lays out the blueprint for the software development.

Coding and unit testing involve implementing the software and testing individual components.

System testing and integration ensure that all parts of the software work together.

Maintenance is a critical phase where most of the effort is spent fixing bugs and issues.

The waterfall model is advantageous for its simplicity and systematic approach.

It is a rigid model with no flexibility for changes once a phase is completed.

Lack of feedback and parallelism can lead to high risk and potential for errors.

The model is not suitable for projects with evolving requirements.

A real-life analogy compares the waterfall model to building a house without the ability to make changes during construction.

The importance of the maintenance phase, where most of the effort is spent addressing issues.

The classical waterfall model is foundational, serving as a base for other software development models.

Transcripts

Dear students welcome to Gate Smashers

In this video I'm going to explain what is classical waterfall model

And all the related points to it

Advantages disadvantages

I will explain each and every fact with example in this video

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Because subscribers are very necessary

So first of all we will start

Over here classical waterfall model

It came at the time of 1970s it is a very old model

Practically if you talk about software development

I don't think so anyone might have used it more

Maybe it might have been used for small projects

Because why it is actually called waterfall

See and waterfall steps are like this in a systematic way

And you can see this diagram like waterfall

Now look the steps in this

Feasibility study is there

Work is the same

We had discussed in SDLC

All the phases that are there in software development life cycle

All that phases are only there

Even if you talk about prototype model spiral model

Are you talk about waterfall

No matter you talk about which model

But all the main points in this

That I'm actually telling you

Look feasibility studies their requirement analysis is there

Specification design is there

Coding and unit testing is there

System testing and integration

And finally we have maintenance

If we talk about feasibility study

What is the meaning of feasibility study

That whether your project is feasible or not

If we talk technically

Are you talk financially

Then whether it is feasible or not

It is not that you have taken such a big project

And your budget is very less

And the project should be technically so sound that

That's somewhere a platform and a team should be available

So first of all we will check that whether it is feasible

Can you make it in that much money

When all that thing will be gathered

And you will go and requirement analysis and specifications

You have checked it

After that what you have finalized

That how much team will I require

How much time will I need you will do the estimation

And you will prepare SRS document over here

So that you can give all the specification in written to your customer

Then we have designing phase

Coding and unit testing

Coding is the same implementation

After that unit testing

You are testing each and every small unit

System testing and integration

You have integrated small units

After that you did system testing

Alpha testing is there beta testing is there

Acceptance testing is there

Later on you will get each and every point

But what happens is in unit testing first to tested each and every unit

After that when you combined all the modules and the system was big

So after integrating it

Alpha testing which is done by the team that is developing it

Beta testing is done by your friendly customer

Acceptance means after checking properly customer will tell whether he will accept this

Or I will not accept this software

And finally comes maintenance

This is a very very important phase

In this

In this the maintenance phase is very important because

Because Sir maximum 60% effort is on maintenance phase only

Why is it so that you will come to know now

What is the meaning of maintenance phase

If any problem comes or any bug comes

You have to fix it

Each and every whatever problem is coming technical or non technical

You have to fix all of them

So look over here

If you talk about its advantages

What are advantages of this model

It is a basic model

It is a very basic model so whichever later on model

Somewhere it is working like a base for them

That means it was the first model

It will tell you that this is the story

Letter on they have removed its problems

So it works like a base

Let us simple it is easy there is no long story in it

Your steps are mentioned in a systematic way

You can say it is easy for small projects

Where all the requirements of customer

He clearly knows

First customer has given a requirement and after that he makes changes in that

No whatever he has told once that is fixed

That is why this model is a bit rigid

There is no flexibility

It is rigid

Why is it rigid? Okay it is an advantage for small projects

But what is the big disadvantage over here

What is your project

Whatever you have told once to your service provider

That I want this

When he has started working

After that you don't have any role

Your role will start when you will get the project

Whatever problem, bugs, issues will come

That will be removed in this phase

That means what is the biggest and major problem over here

There is no feedback

What is not there? Feedbacks are not there

That means whatever work you have done over here you have handed it over to the next team

Then you handed it to next team

Now if anyone feels in between that there is some problem

I should tell to the previous team

That rectify it a bit

No it is not there

The model is very rigid it tells I'm not going to do any changes

Once what is done in one phase

Then it will go in next phase only

No value will go in back phase

Then if you talk about experiments

It is the same thing that you cannot do any changes

Or you cannot bring any new experiment over here

Whatever the previous team has done that only you will have to carry forward

You have to submit it to the next to the next in this way you have to work

There is no parallelism

What is the meaning of parallelism

That at a time multiple teams can work

No

Over here it is not so first this team will work

Other teams are sitting idle

When this team has got work other teams are sitting idle

When he has got to work others are sitting idle

That means parallelism is not there

At a time you are not doing multiple work

High risk is there obviously there will be high risk

Because rigidity is there

Over here flexibility is not there

So risk will be there

Why? Because all the problem that is occurring

That all you will be able to see in the last phase

If I tell you this with our simple and real life example

You want to make your dream house

You took land

You got a map prepared from an architect

Each and everything is done

You have also given money to the builder

Builder has built the house

That means the time from which you purchased your house till your grah privesh

You have not seen what is going on how is it going on

When you have to go inside the house

Then you saw that here is the mistake

Kitchen is very small

Bedroom should not have been over here, it should have been over here

I want to do this, now if you will do changes

Batman's your directly doing this change in maintenance phase

That means you have entered the house and along with that you have also started breaking it

Sometimes you will break here, sometimes you will do this

So obviously it is such a big problem

It's better that you have a feedback system in between only

If there is any mistake

If there is any problem

We can remove it in that phase only

In that phase only we can fix bugs

This thing is missing over here

That is why 60% effort is there in maintenance phase only

Because other phases have done their work and are sitting relaxed

They know that whatever problem will come, it will come in maintenance phase and at that time we will solve it

Maintenance again and again you will have bugs and problems

Because actually when the customer got the software and he has given to his users ahead

At that time all the problems will occur

And then you will slowly try to remove them

So somewhere your time will also be wasted

Obviously you will require extra money also

So these are the major problems over here

In classical waterfall model

There is nothing in it other than this

No matter whatever they ask you

If you have told these points

This is more than sufficient

Thank you