Waterfall Model

WATERFALL MODEL

Ø  WFM states that the phases are organized in a linear order. It is also referred as linear sequential life cycle model.

Ø  Each phase must be completed in its entirety, before the next phase can begin.

Ø  There r 2 assumptions made, when we work with WFM

v  For a successful project resulting in a successful product, all phases listed in WFM must be performed in anyways.

v  Any different ordering of the phases will result in a less successful software product.

Ø  In a typical model, a project begins with feasibility study. On successful demonstrating the feasibility of project, the requirements analysis & project planning begins. The design Starts after the requirements analysis is completed & coding begin after the design is completed. Once the programming is completed, the code is integrated & testing is done. On successful completion of testing, the system is installed. After this, the regular operations & maintenance of the system takes place.

Ø  When the activities of the phase r completed, there should be some product that is produced by the phase. The Goal of a phase is to produce this product. The o/ps of the earlier phases r often called WORK PRODUCTs (or intermediate products) & r usually in the form of documents like the requirement doc or design doc.

Ø  O/Ps of phases r-   
1>Requirement Doc
2>Project Plan
3>System Design Doc
4>Detailed Design Doc
5>Test plan & Test Reports
6>Final Code
7>Software manual(e.g. User, installation etc)

ADVANTAGES

1)      Simple & easy to use.

2)      Phases r processed & completed one at a time.

3)      Work well for smaller projects where requirements are very well understood.

4)      Easy to manage due to rigidity of Model-each phase has specific deliverables & a review process.

      DISADVANTAGES

1)      The requirements of the system can be frozen before the design begin, we can’t change SRS if design is done.

2)      Working s/w produced at the end of all phases so there is a long wait.

3)      High amt of risk & uncertainty.

4)      Poor Model where requirements r at a moderate –high risk of changing.

5)      Poor Model for long n ongoing projects.

6)      Poor Model for complex & Object oriented projects.