Spiral Model

Hello friends! In this tutorial, we will study one of the most common SDLC models, the Spiral model. The major benefit of the Spiral model is its ability to handle risk in different phases of software development. So, let’s begin with the definition, phases, advantages, and disadvantages of the Spiral model and see its risk handling ability.

What is a Spiral Model? 

The spiral model is an SDLC model that combines elements of an iterative software development model with a waterfall model. It is advisable to use this model for expensive, large and complex projects. 

In its diagrammatic representation, the spiral model looks like a coil having many cycles or loops. The number of cycles varies for each project and is usually specified by the project manager. Each spiral cycle is a stage in the software development process. 


The Spiral Model allows the product to be rolled out and refined in each phase of the spiral, with the ability to build prototypes in each stage. A prototype is created at the beginning of each phase as a risk management technique.

The most important feature of the model is that once the project starts, it has the ability to manage unknown risks. Let’s go through the different phases of the Spiral model first and after that, we would be able to see how risk is handled in this model.

Spiral Model Phases

It has four stages or phases: The planning of objectives, risk analysis, engineering or development, and finally review. A project passes through all these stages repeatedly and the phases are known as a Spiral in the model.

  1. Determine objectives and find alternate solutions – This phase includes requirement gathering and analysis. Based on the requirements, objectives are defined and different alternate solutions are proposed.
  2. Risk Analysis and resolving – In this quadrant, all the proposed solutions are analyzed and any potential risk is identified, analyzed and resolved.
  3. Develop and test: This phase includes the actual implementation of the different features. All the implemented features are then verified with thorough testing.
  4. Review and planning of the next phase – In this phase, the software is evaluated by the customer. It also includes risk identification and monitoring like cost overrun or schedule slippage and after that planning of the next phase is started.

Spiral Model Advantages

The advantages of the Spiral Model are explained below-

  1. The spiral model is perfect for projects that are large and complex in nature as continuous prototyping and evaluation help in mitigating any risk.
  2. Because of its risk handling ability, the model is best suited for projects which are very critical like software related to health domain, space exploration, etc.
  3. This model supports the client feedback and implementation of change requests (CRs) which is not possible in conventional models like a waterfall.
  4. Since customer gets to see a prototype in each phase, so there are higher chances of customer satisfaction. 

Spiral Model Disadvantages

Some of the disadvantages of the spiral model are given below.

  1. Because of the prototype development and risk analysis in each phase, it is very expensive and time taking.
  2. It is not suitable for a simpler and smaller project because of multiple phases.
  3. It requires more documentation as compared to other models.
  4. Project deadlines can be missed since the number of phases is unknown in the beginning and frequent prototyping and risk analysis can make things worse.

Conclusion

I hope now you must have got a fair understanding of the Spiral model along with its features, pros, and cons. Let us know in the comments, in case of any query and we will reply at the earliest. Check our complete software testing tutorial course here – Software Testing Tutorial.

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