What is Spiral model in software engineering

What is Spiral model in software engineering


The Spiral model is an evolutionary software process models that couples the iterative nature of prototyping with controlled and systematic aspects of the linear sequential model. During the early iteration, the model might be a proper model or prototype. During later iteration of the spiral model is not fixed and can vary from project to project. It iteration of the spiral is called a phase of the software process.

Each phase in this model phase is divided into a number of framework activities also called the task part or task region. Basically, there is four region.

Namaste I Niteen Kumar. Today I am going to discuss the question of what is spiral model in software engineering. What are the advantages and disadvantages of the spiral model in software engineering? We discuss with a proper diagram. So let’s start our topic what is spiral model in software engineering.

what is spiral model in software engineering
what is spiral model in software engineering

Spiral Model Diagram and expalnation

Look at this diagram here you can find that the particular software development process has got initiated. Where having a risk management prototype, design coding integration, test, and the last one implementation.
Now one release will be obtained to the client so that client can use it and here you see what having the next phase planning.and then we are going for the review than for the objective identification then cumulative cost again the progress will be initiated and then alternate evaluation will be done and then again we are going for this product development phases.

So, in this way the spiral model will work. Look at this particular figure and you can find that the risk management is taking care of the process of the spiral model so this is the uniqueness of the spiral model. So after this discussion now let see the exact answer of what is spiral model in software engineering?

spiral model

Spiral Model is a combination of both, the iterative model and one of the SDLC model. It can be seen as if you choose one SDLC model and combined it with the cyclic process(iterative model).
piral model is suitable for large software because software evolves as the process progress. The customer and developer better understand and react to risk at each phase. Finally, this model has not to be used as widely as the waterfall model or prototyping model because it will take a numbers of year to develop the software.

  • The Spiral model was first mentioned by Barry Boehm in 1986.
  • The Spiral model is more emphasis placed on risk analysis.
  • Each phase in spiral model begins with a design goal and ends with the client reviewing the progress.
  • The spiral model has four phases. They are Planning, Risk analysis, Engineering and Evaluation.
  • A software project repeatedly passes through these phases in iterations. The baseline spiral starting in the planning phase requirements are gathered and risk is assessed.
  • The development team in Spiral- SDLC model starts with a small set of requirement and goes through each development phase for those set of requirements.


The spiral model is used in these conditions. They are:-

  • when project size is too large.
  • Where the software needs continous risk evaluation.
  • Requirements are a bit complicated and require continuous clarification.
  • When the software requires significant changes.
  • Where enough time frame is there to get the end user feedback.
  • Where releases are required to be frequent.


Each phase in this model is divided into a number of framework activities also known as the task part or task region. Basically, there is four task region.

Planning phase (1st Task Region)

The objectives are investigated and analyzed the risk involved in this region are identified.
This phase starts with gathering the business requirements in the baseline spiral. In the subsequent spirals as the product matures, identification of system requirements, subsystem requirements and unit requirements are all done in this phase. Requirements are gathered during the planning phase. Requirements like ‘BRS’ that is ‘Business Requirements Specification’ and ‘SRS’ that is ‘System Requirement Specifications’.

Risk Analysis (2nd Task Region)

In this region, alternative solutions are evaluated to select the best possible solution.
In the Risk analysis phase, a process is undertaken to identify risk and alternate solutions. A prototype is produced at the end of the risk analysis phase. If any risk is found during the risk analysis then alternate solutions are suggested and implemented.

Engineering Phase (3rd Task Region)

It consists of developing and verifying the next level of the software.
This is the main phase of this model. Actual development and testing if the software takes place in this phase. In this phase software is developed along with testing at the end of the phase. Hence in this phase the development and testing is done.

Evaluation Phase (4th Task Region)

The task required to obtain customer feedback based on the evaluation of the software representation created during the engineering stage and implemented during the installation stage.
This phase allows the customer to evaluate the output of the project to date before the project continues to the next spiral. Customers evaluate the software and provide their feedback and approval.

Spiral model in software engineering
Spiral model in software engineering


  1. Development is fast.
  2. Very good for large and complex projects.
  3. Large projects are created and handled in a startegic way.
  4. Risk evaluation is proper.
  5. Control towards all the phases of development.
  6. More and more features are added in a systematic way.
  7. Software is produced early.
  8. Has room for customer feedback and the changes are implemented faster.
  9. Customer connectivity vey well with developer.


  1. Risk Analysis is important phase so requires expert people.
  2. Is not benefical for smaller projects.
  3. Spiral may go infintely.
  4. Documentaion is more as it has intermedite phases.
  5. It is costly for smaller projects.
  6. It may take a number of years to complete one projects.
  7. Time spent panning, resetting objectives, doing risk analysis and prototyping may be excessive.
  8. The model is complex.
  9. Risk assesment expertise is required

Thanks For reading our article about What is spiral model in software engineering. Hope you have got your all answers if not then related to this topic comment down your question I will answer it. For what is waterfall model in software engineering please click on the given link mota-bro.com Thank you. If you want to read about the spiral model in Hindi please click on this link Chotabro.com

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