Incremental Model, advantages, examples, Case study

There are many software process models that can be implemented by software engineers. Some famous process models are the waterfall model, spiral model, iterative model, and agile model, etc. In other tutorials, we will also learn about these topics. Here our main focus is to discuss the incremental model. So, let’s start our discussion about the incremental model.

According to the incremental model, the software is divided into separate modules(components)and each of these modules has a separate set of waterfall activities including requirements gathering and analysis, design, implementation, deployment, and maintenance.

When any component is ready, then the component is delivered to the customer and when remaining components become ready than delivered to the customer one by one by integrating new components with old once.

Example of the incremental model (Just for understanding)

incremental model in software engineering

In this daily life example, we want to draw a picture, first, we draw the first part of the picture as shown in increment 1, Similarly after completing the first part of the picture we have to add one another part of the picture labeled as increment 2 in the above picture. Similarly, we complete this picture in four increments.

A case study of incremental model

Suppose we want to develop a web-based social network with the following functionalities;

The user should signup for the system.

The user should log into the system and can send or accept the friend request.

How can use the incremental model in this scenario;

Solution:

We need to convert this system into separate components;

Component 1: Sign up and log in

Component 2: Send Friend request

Component 3: Accept friend request

Now, when we start our activities, then we can start with component 1(signup and login). This component undergoes the phases of requirements gathering and analysis, design, implementation, deployment, and maintenance. When this component is ready, we deliver this one component to the customer.

incremental model in sdlc

Figure: incremental model

After that, we add or increment another component 2 that sends the friend request. This component undergoes the phases of requirements gathering and analysis, design, implementation, deployment, and maintenance. When this component is ready, we deliver this one component to the customer.

incremental software development

Figure: incremental model

After that, we add or increment another component 3 that accepts a friend request. This component undergoes the phases of requirements gathering and analysis, design, implementation, deployment, and maintenance. When this component is ready, we deliver this one component to the customer.

incremental-model-in-software-engineering2

Result: In this case study we observe that one system is produced and delivered to the customer in increments.

What are the advantages of an incremental model?

  1. Customer feedback is received after the delivery of each component.
  2. Risk of requirement changes is reduced
  3. More flexible
  4. Easy to test and debug
  5. Give quick results

What are the disadvantages of an incremental model?

  1. Needs a proper plan to integrate the components
  2. Needs a proper design to integrate the components
  3. More expansive as compared to the waterfall model.

When to use the incremental model?

  1. When major requirements are understood but some requirements can evolve within the passage of time.
  2. When product launch in the market is getting late.
  3. When a customer has no problem with the budget but he demands more and more quality in software.

Difference between incremental model and Iterative Model

Let’s see the Difference between the Iterative and incremental models with a diagram.

Comparison of Iterataive model vs incremental model in software engineering

Difference between incremental model and waterfall Model

Let’s see the Difference between the incremental and waterfall model with a diagram.

INCREMENTAL MODEL WATERFALL MODEL
Detailed  documentation is not strictly Required in Incremental model. Detailed  documentation is strictly Required in Waterfall model.
Returning to previous stage/phase is allowed in waterfall model. Returning to previous stage/phase is never advice in waterfall model.
Testing is done after every iteration of phase in incremental model. Testing is done after completion of all coding phase in waterfall model.
Low risk in incremental model. More  risk in waterfall model.
Incremental model can’t handle large project. Waterfall model can’t handle large project.
Early stage planning(not Extremely)  is necessary in Incremental model. Early stage planning(Extremely) is necessary in Waterfall model.
Delivery time is short. Delivery time is not short.
There are  multiple development cycles take place in incremental model. There is only one development cycles in waterfall model.
Cost of incremental model is Low. Cost of Waterfall model is Low.
Flexibility to change in incremental model is Easy. Flexibility to change in waterfall model is difficult.
Overlapping of phases is possible in waterfall model. Overlapping of phases is not possible in waterfall model.
Large team is not required in waterfall model. Large team is require in waterfall model.

 

Comparison of SDLC Models

Comparison of incremental model and spiral model

Properties Incremental Spiral
Objectives Rapid Development High Assurance
Planning in early stage Yes Yes
Returning to an earlier phase Yes Yes
Handle Large-Project Not Appropriate Appropriate
Time-Frame Long Long
Working software availability At the end of every iteration At the end of every iteration
Risk Involvement Low Medium to high risk
Software Team size Not Large Software Team Large Software Team
Customer control over administrator Yes Yes
Maintenance Promotes Maintainability Typical
Time Duration Very long Long
Re-usability To some extent To some extent
Framework Type Linear + Iterative Linear + Iterative
When Testing? After every iteration At the end of the engineering phase
Maintenance Maintainable Yes
Detailed Documentation Yes but not much Yes
Overlapping Phases Yes No

Comparison of incremental model and RAD

Properties Incremental Rad
Objectives Rapid Development Rapid development
Planning in early stage Yes No
Returning to an earlier phase Yes Yes
Handle Large-Project Not Appropriate Not Appropriate
Time-Frame Long Short
Working software availability At the end of every iteration At the end of the life cycle
Risk Involvement Low Low
Software Team size Not Large Software Team Small Software Team
Customer control over administrator Yes Yes
Maintenance Promotes Maintainability Easily Maintained
Time Duration Very long Short
Re-usability To some extent Yes
Framework Type Linear + Iterative Linear
When Testing? After every iteration After completion of development
Maintenance Maintainable Easily Maintainable
Detailed Documentation Yes but not much Limited
Overlapping Phases Yes Yes

Comparison of incremental model and Waterfall

Properties Incremental Waterfall
Objectives Rapid Development High Assurance
Planning in early stage Yes Yes
Returning to an earlier phase Yes No
Handle Large-Project Not Appropriate Not Appropriate
Time-Frame Long Very Long
Working software availability At the end of every iteration At the end of the life-cycle
Risk Involvement Low High
Software Team size Not Large Software Team Large Software Team
Customer control over administrator Yes Very Low
Maintenance Promotes Maintainability Least
Time Duration Very long Long
Re-usability To some extent Least possible
Framework Type Linear + Iterative Linear
When Testing? After every iteration After completion of development phase
Maintenance Maintainable Least Maintainable
Detailed Documentation Yes but not much Necessary
Overlapping Phases Yes No

Hopefully, now you are able to answer the following questions;

  1. What is an incremental model?
  2. What are the disadvantages of an incremental model?
  3. What are the advantages of an incremental model?
  4. When to use the incremental model?

Frequently Asked Questions (FAQ)

Question: What are example of software that use incremental model?

Answer: Approximately, every software that provides updates time to time.

Question: The unified process is an interative and incremental approach to developing software. True/False

Answer: True

Question: Incremental development is the most effective approach for developing business software systems

Answer: True

Conclusion

An incremental model is best when you want to develop software with different increments.

Incremental model MCQs Test

Test your understandings with incremental model MCQs Test.

Iterative model MCQs Test

Test your understandings with iterative model MCQs Test.

Software process models MCQs Test

Test your understandings with software process models MCQs Test.

Case studies for Software process models

Try to guess the software process model for the following case studies.

The Evolutionary model is a combination of incremental and iterative models.

incremental model in software engineering | incremental model in software engineering ppt | incremental model pdf | incremental model examples.

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