The spiral model has four phases: Planning, Design, Construct and Evaluation. A software project repeatedly passes through these phases in iterations (called Spirals in this model).
Sprial model is a iterative model. Spiral model overcomes the drawbacks of waterfall model.
We follow spiral model whenever there is dependency on the modules.
In spiral model, for every cycle new software will be released to customer. Software will be released in multiple versions. So it is also called as "version control model".
When we use Spiral Model ?
The folllowing points explain the use of spiral model:
- When project is large.
- When releases are required to be frequent.
- When requirements are unclear and complex.
- When projects are medium to high risks.
Advantages of Spiral Model:
These are some advantages of spiral model:
- Testing is done in every cycle, before going to the next cycle.
- Customer will get to use the software for every module.
- Requirement changes are allowed after every cycle before going to the next cycle.
- It is recommended to use the Spiral Model in large and complex projects.
Disadvantages of Spiral Model:
These are some disadvantages of spiral model:
- Requirement changes are not allowed in between the cycle.
- Process is complex.
- Every cycle of spiral model looks like waterfall model.
- There is no testing in requirement and design phase.
