Spiral Model
It is a combination of waterfall Model and interactive model.Each phase in spiral model begins with the designing goal end with the client review and progress.
The development team in Spiral SDLC Model starts with a small set of requirements and goes through each development phase for those set of requirements. The software engineering teams adds functionality for the additional requirement in every increasing spiral until the application is ready for the production phase.
In spiral model we have four phases.
1) Planning: -
It including estimated the cost scheduling and resources for the interaction. It also involves understanding the system requirements for communication between the system analysis and the customer.2) Risk Analysis: -
Identification of potential Risk is done while Risk is planning and finalized.3) Engineering: -
It’s includes testing coding and displaying software at the customer site.4) Evaluation: -
Evaluation of software by the customer also include identified risk such as schedules supply and cost overcome.When Use Spiral Methodology
1) When project Is large.2) When releases are required to be frequent.
3) When creation of prototype is available.
4) When risk cost evaluation are important.
Advantage
• Additional functionality or changes may be done at a later stage.• Cost estimation becomes simple because the prototype building is finished in tiny fragments.
• Continuous development helps in risk management.
• There is usually an area for client feedback.
Disadvantage
• Risk of not meeting the schedule square measure budget.• It works best for large projects only additionally demands risk assessments experience.
• For its smooth operation spiral model protocol must be followed strictly.
• It isn't obtainable for smaller project it right value them a great deal.
Also Read : Prototype Model
