Spiral model is one of the most important Software Development Life Cycle models, which provides support for Risk Handling. It is a combination of waterfall model and iterative model. This model is best used for large projects which involve continuous enhancements. Each phase of spiral model in software engineering begins with a design goal and ends with the client reviewing the progress. The development process in Spiral model in SDLC, starts with a small set of requirement and goes through each development phase for those set of requirements. The software engineering team adds functionality for the additional requirement in every-increasing spirals until the application is ready for the production phase. In its diagrammatic representation, it looks like a spiral with many loops. The exact number of loops of the spiral is unknown and can vary from project to project. Each loop of the spiral is called a Phase of the software development process.
Also check:- Waterfall Model(SDLC)
Different Phases of Spiral Model
- Planning phase
- Risk Analysis
- Development phase
- Evaluation
Planning phase
In this phase, requirements are gathered from the customers and the objectives are identified, elaborated, and analyzed at the start of every phase. This phase also includes understanding the system requirements by continuous communication between the customer and the system analyst. It also includes estimating the cost, schedule and resources for the iteration.
Risk Analysis
Requirements are studied and brain storming sessions are done to identify the potential risks. Then the risks associated with that solution are identified and the risks are resolved using the best possible strategy.
Development phase
In this phase, the the identified features are developed, tested and deployed at the customer site.
Evaluation
In this phase, the project is reviewed, and a choice made whether to continue with a further period of the spiral. If it is determined to keep, plans are drawn up for the next step of the project.
Advantages of Spiral Model
Changes made to the requirements after development has started can be easily adopted and incorporated. Additional functionality or changes can be done at a later stage. The spiral model involves risk analysis and handling in every phase, improving security and the chances of avoiding attacks and breakages. The iterative development process also facilitates risk management.
Dis-advantages of Spiral Model
The spiral model is expensive, so it is not suitable for small projects. For its smooth operation spiral model protocol needs to be followed strictly. The spiral model is more complex than other SDLC options. For it to operate efficiently, protocols must be followed closely. Furthermore, there is increased documentation since the model involves intermediate phases.
