As in waterfall model requirement changes are not allowed they went for a new model called Spiral Model.
When do we choose Spiral Model?
- We go for spiral model whenever modules are dependent on each other.
- In spiral model we are going to develop and test module by module and hand it over to the customer so that changes can be easily handled.
- For example consider a product which is having three modules Module A, Module B and Module C
- First we are going to collect the requirements of Module A, design of Module A, Coding for Module A and test Module A.
- Finally Module A is handed over to the customer.
- Similarly we are going to collect the requirements , Design, coding and testing for Module B.
- In the testing process we are going to test first module B, then Integration of modules A and B (A+B).
- The same process continues for all modules.
Spiral model also called as Iterative Model.
- In case of minor changes we are going to implement the new requirements and changes in the same cycle. we don’t go for an extra cycle.
- In case of major changes we go for an extra cycle as the changes may effect the existing features.
- Flexible for changes.
- Customer can use the product at an early stage.
- It is easy to develop and easy to test since it is developed module by module.
- No requirements review ie., no one are going to cross check the requirements that are taken by the BA or PA.
- No parallel deliverables ie, No two steps will be working at the same time.
Q) When we go for Spiral Model?
Ans: When ever modules are dependent on each other then we go for Spiral model.