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Spiral Model of SDLC – Pros, Cons, Phases, Why We Need It

What is SDLC?

A software development life cycle (SDLC) known as the spiral model was created by Barry Boehm in the year 1986. Managing both the time and the money spent on the process of developing software is the primary motivation behind the creation of this model. As is common knowledge, the SDLC consists of multiple phases, some of which are titled “Requirements,” “Design,” “Coding,” and “Testing,” among others. The software product is being developed as we progress through these phases of the process. From the pov of the customers, the completion of each phase came at a substantial cost, both monetarily and in terms of the amount of time it took.

The primary objective of utilising this model is to exercise management or control over such a significant expenditure at each and every phase step. b This model’s strategy involves optimising each phase step that involves doing some activities multiple times. Doing these activities multiple times results in a significant increase in cost. The spiral model places a greater emphasis on gathering and configuring the requirements in their entirety before moving on to the subsequent step.

Therefore, the primary objective of the spiral model is to achieve the greatest possible cost savings throughout each phase of the SDLC process.

Why we need Spiral Model in SDLC?

The primary goal of developing the spiral model is to reduce the amount of money and time spent during each phase step of the SDLC process. However, before we continue, what refer to “cost” in this context, it is referring to both the financial and the time costs. The primary objectives and goals is to find the best possible way to reduce the total cost of the software development process.

Let’s talk about how utilising this model can help us save both time and money throughout the various phases of the project. First things first, let’s get into the requirements phase: Before we can move on to the design phase, we need to make sure that we have collected all of the user requirements in the appropriate manner. It is a widely held belief that just the process of gathering requirements will take up more than forty percent of the total time allotted to the project. On the other hand, if the spiral model is applied, the vast majority of these efforts will be able to be recycled into later phases.

So what will actually happen? As soon as user requirements are gathered, they are stored in a database or other document repository. The software design process then begins. When the design is finished, we can extract it into code. This is how applying this model allows us to save money.

The spiral model can also be used in the following other ways to lower the cost of each phase step: Schedule regular user group meetings, such as weekly or monthly, and inform them of the most recent situation regarding project progress. The price of requirement gathering will go down. Do not wait to start the design phase until all requirements have been gathered. Start with the more important first requirements and move forward as soon as you can. Don’t wait until you have fully collected all of the user requirements. Since most of the work completed in one phase can be used in later phases, this can significantly reduce the amount of development time required at each stage.

In conclusion, the Spiral model is a successful method for creating any type of software product because it saves time and money during each phase step. Another benefit of this model is that numerous time-consuming tasks, such as requirement gathering and designing, can be reused for the following phase. Because of this, more businesses are using this strategy today than they did in the past.

Spiral Model Phases

The spiral’s phases or cycles are divided into four quadrants, and each phase or cycle is followed repeatedly until the project is finished. The spiral model has four quadrants, which are:

  1. Determine your goals and find different solutions.
  2. Risk evaluation and mitigation
  3. Create and test the project.
  4. Planning and evaluation
  5. Objectives determination and identify alternative solutions.

The baseline spiral is employed at this point to collect the company needs. Following this stage, as the product develops, system requirements, subsystem requirements, and unit requirements are identified. Customers’ requirements are gathered, objectives are identified, explained, and analysed at the beginning of each step. Then, alternative solutions to the phase are provided in this quadrant.

It includes calculating the budget, schedule, and resources for the iteration. In order for the system analyst and the client to stay in constant contact, this quadrant also involves a thorough understanding of the system’s requirements.

  1. Risk Assessment and reduction.

All viable options are examined in the second quadrant in order to select the best one. The risks associated with that solution are then determined, and using the best method possible, the risks are minimised. For the best possible solution, the prototype is created at the end of this quadrant. Technical viability and management risks, like schedule slippage and cost overrun, are identified, estimated, and tracked through risk analysis. Possible risks are being identified as a risk mitigation strategy is developed and finalised.

  1. Develop and Validate the project.

This quadrant provides options for addressing the risks and uncertainties; for example, benchmarking, simulation, and prototyping are all potential steps in this process. This phase represents the production of the actual software product and occurs at each and every spiral.A Proof of Concept (POC) is created at the first ideation and design phase of the baseline spiral so that input can be gathered from users.

The next step is to create a functioning model of the programme, which is referred to as a build and is assigned a version number. This happens as the needs and design specifics become clearer in subsequent spirals. The characteristics that can be found in the third quadrant are being worked on and evaluated. At the conclusion of the third quadrant, the subsequent version of the software will be made available.

  1. Planning and Review.

The final step is to plan and then review what you’ve done. After conducting an analysis of the project, a determination is made regarding whether or not to proceed with the spiral one more time. In the event and occasion that it is decided to continue using it, the plans for the subsequent stage of the project will be drafted. The risks that are still present will determine whether or not the development phase is carried out. If it is determined that the risks associated with performance or the user interface are more significant than the risks associated with the development of the program, the subsequent phase may consist of an evolutionary development that includes the creation of a more comprehensive prototype to address the issues.An essential component of the idea is represented by the fact that each level of the spiral concludes with a review that not only examines all of the products made during the preceding cycle but also makes preparations for the cycle that will come after it. The spiral model is applicable to both the creation of new projects and the improvement of existing ones. In the fourth quadrant, customers provide feedback on the software that has been developed up to this point. Recognizing and keeping an eye on potential dangers, such as a project running over budget or behind schedule, is also a part of the job.

Risk Handling in Spiral Model

Any potentially detrimental circumstance that could jeopardise the successful completion of a software project is referred to as a risk. The management of these unknown risks after the project has already begun is the aspect of the spiral model that is considered to be the most important. Developing a prototype makes it simpler to implement risk mitigation strategies like these. The spiral model facilitates copying up while accounting for potential risks by allowing for the construction of a prototype during each stage of the software development process.

The Prototyping Model also offers support for risk management; however, all of the risks associated with the project need to be identified before the development phase of the project can begin. However, in real-world projects, risks may not become apparent until after development work has begun; if this is the case, we will be unable to use the Prototyping Model effectively. The characteristics of the product are documented and evaluated at each stage of the Spiral Model, and any risks that are discovered are pinpointed before being mitigated through the use of prototyping. Therefore, in comparison to other SDLC models, this model has a great deal more adaptability.

Uses of the Spiral Model

The spiral model is most effective when applied to extensive, costly, and difficult endeavours that involve both external and internal dependencies. Additional applications include:

  • Projects in which frequent releases are necessary.
  • Projects in which changes may be required at any time.
  • Long-term projects that cannot be implemented because shifting economic priorities make them impractical.
  • Projects with moderate to high levels of risk.
  • projects where careful consideration of both cost and risk is required.
  • Those projects where the development of a prototype would be beneficial.
  • projects with requirements that are either unclear or complex.

When it comes to SDLC, what are the benefits of using a spiral model?

Utilizing the spiral model for the development of software has a number of benefits in comparison to utilising some of the other models available. The following is a list of several of these advantages:

  • It is very simple to implement new features into the software when using this model because it promotes iterative and incremental process development. It is possible to modify any of the functionality without expending a lot of time or money on the endeavor. This model also provides a clearly defined structure, with each phase having distinct goals, deliverables, and dependencies on the one before it. As a result, the transition through each stage of the SDLC process is made easy and unbroken.
  • Because of the timely identification of risks and the steps taken to mitigate them, the number of problems that could have otherwise arisen later on in the life cycle of the project is reduced.
  • If clear and explicit deliverables are defined for each phase, there is also the possibility of significantly lowering the cost of the project by effectively managing the resources that are available for the project. The value of the spiral model is demonstrated in yet another context by the fact that it can assist you in locating and resolving problems well in advance of any situation becoming urgent, as this example demonstrates.
  • This model, which calls for using a clear business plan and a top-down approach to problem solving, is ideal for IT organisations that are highly dependent on one or more business-related factors in order to make a profit. After all, development is costly, so it is preferable to deliver high-quality software products at the right time while taking as few risks as possible.
  • Because it is so meticulously structured, this model makes it much simpler to handle the day-to-day tasks that need to be done. Because of this, the team working on your project will be able to concentrate solely on the tasks that have been assigned to them, as opposed to juggling a greater number of responsibilities as in other models, such as the Waterfall SDLC.
  • In conclusion, if you have a fresh concept that you are considering developing into a product in the future, the spiral model can be of great assistance to you in demonstrating that your concept is both practical and realisable. To accomplish this goal, all that is required is to locate and define every aspect of the scope of your project.

Because it offers so many advantages, it should be clear that, in contrast to the waterfall model of the software development life cycle (SDLC), which concentrates only on the creation of the software, the spiral model concentrates on every other facet of project preparation. This can help you reduce risks and, in the end, guarantee the success of your project. This is because the spiral model prioritises the preparation of the project as a whole. The benefits that were discussed earlier are just some of the most important ones that are currently available. However, even these are sufficient evidence to demonstrate that the spiral model is superior to the waterfall software development life cycle (SDLC), as well as any other software development model.

What drawbacks does the spiral model have in the SDLC?

Is there anything that could go wrong if I decided to use the spiral model? Yes, just like with any other model for the creation of software, this one comes with its fair share of potential pitfalls as well. the drawbacks are listed as below:

  • Because you have already developed and build the system, the time is very short, and as a result, there is no room for any innovative ideas. Your project team will have a more difficult time coming up with new and innovative ideas as a result of this, ideas that would have otherwise been possible using a Waterfall SDLC.
  • This model primarily focuses on software development, which may delay the release of any products to the market and reduce your chances of profitability because you won’t have a competitive time advantage.
  • There is a significant risk of missing any one of these deliverables because each phase has very specific requirements and a limited time frame. This may result in adjustments to performance metrics, which would harm the goals of your project.
  • Your team members may find it challenging to balance their immediate tasks with the big picture because you are considering multiple phases. As a result, they risk losing all sense of the project’s goals.


Softwaretestingo Editorial Board. (2021, December 26). Spiral Model Of Software Development in Software Engineering. https://www.softwaretestingo.com/spiral-model/

Singla, S. (2022, February 2). Spiral Model in Software Engineering. Scaler Topics. https://www.scaler.com/topics/software-engineering/spiral-model-in-software-engineering/

Spiral Model (Software Engineering). (2022, August 22). InterviewBit. https://www.interviewbit.com/blog/spiral-model/

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