SOFTWARE LIFE CYCLE MODELS
1. Waterfall Model
- Waterfall Model is the oldest SDLC Mode
- It resembles how the water fall flows from up side to down side
- It will proceed Phase by Phase
All the requirements should be ready to proceed to other next phases - Testing team is not involved from the beginning stages, hence defect fixing becomes time consuming
- and costly
- Any changes in Requirements, Design or Defects to be fixed, we have to moved back to respective
- phases and again come down
- Takes lot of time to see the working product
Advantages of Waterfall Model
- Quality of the product will be good.
- Since Requirement changes are not allowed , chances of finding bugs will be less.
- Initial investment is less since the testers are hired at the later stages.
- Preferred for small projects where requirements are feezed.
Disadvantages of Waterfall Model
- Requirement changes are not allowed.
- If there is defect in Requirement that will be continued in later phases.
- Total investment is more because time taking for rework on defect is time consuming which leads to
- high investment.
- Testing will start only after coding.
2. V-model
- In the Phase by Phase models, we have to recheck the previous phases if we find any defects in testing which is lately introduced in the SDLC
- V Models solves this problem as Testing is introduced from the beginning itself
- Frequently changed requirements are not addressed in this Model
Advantages
- Testing is involved in each and every phase.
Disadvantages
- Documentation is more.
- Initial investment is more.
3. Spiral Model
Spiral Model is iterative model.
- Spiral Model overcome drawbacks of Waterfall model.
- We follow spiral model whenever there is dependency on the modules.
- In every cycle new software will be released to customer.
- Software will be released in multiple versions. So it is also called version control model.
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.
Disadvantages of Spiral Model
- Requirement changes are NOT allowed in between the cycle.
- Every cycle of spiral model looks like waterfall model.
- There is no testing in requirement & design phase.
