The spiral model is a combination of sequential and prototype models. This model is best used for large projects which include persistent improvements. There are explicit activities that are done in one iteration (spiral) where the output is a small prototype of the large software. Similar activities are then repeated for every one of the spirals until the whole software is built.

What is Spiral Model?

Spiral Model is a risk-driven software development process model. It’s a combination of waterfall model and iterative model. Spiral Model assists to adopt software development elements of numerous process models for the software project dependent on unique risk designs ensuring proficient development process.

Each phase of spiral model in software engineering starts with a design objective and finishes with the client reviewing the progress. The spiral model in software engineering was first referenced by Barry Boehm in his 1986 paper.

The development process in Spiral_model in SDLC, begins with a small arrangement of prerequisite and goes through each development stage for those arrangement of necessities. The software engineering team adds usefulness for the extra prerequisite in every-increasing spirals until the application is prepared for the production stage. The underneath figure clarify Spiral_Model:

Spiral Model Phases

Spiral Model PhasesActivities performed during phase
PlanningIt incorporates assessing the expense, timetable and resources for the iteration. It likewise includes understanding the system prerequisites for continuous communication between the system analyst and the customer
Risk AnalysisIdentification of potential risk is done while risk mitigation strategy is arranged and finalized
EngineeringIt incorporates testing, coding and deploying software at the client site
EvaluationEvaluation of software by the client. Additionally, incorporates identifying and observing risks, for example, schedule slippage and cost overrun

When to use Spiral Model?

• A Spiral model in software engineering is used when project is large

• When releases are needed to be incessant, spiral procedure is used

• When creation of a prototype is applicable

• When risk and costs evaluation is significant

• Spiral technique is useful for medium to high-risk projects

• When necessities are hazy and complex, Spiral_model in SDLC is useful

• When changes may need whenever

• When long term project responsibility isn’t possible because of changes in economic priorities

Spiral Model Advantages and Disadvantages

Extra usefulness or changes should be possible at a later stageRisk of not meeting the timetable or budget
Cost estimation turns out to be simple as the prototype building is done in small fragmentsSpiral development turns out best for enormous projects just additionally demands risk appraisal expertise
Constant or repeated development helps in risk managementFor its smooth operation spiral model protocol should be followed stringently
Development is fast and highlights are included a systematic path in Spiral developmentDocumentation is more as it has intermediate stages
There is consistently a space for customer feedbackSpiral software development isn’t advisable for smaller project, it might cost them a lot


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