Waterfall Model

Before learning the waterfall model let you know about:
Software bidding: A proposal to develop new software is called as ‘software bidding’
 If a proposal came from the customer point of view then it is called as “software project bidding”.
 If a company will study the needs of the market and develop the software then that type of proposal is called as “software product bidding”

Note: The above waterfall model is also called as the “Linear Sequential Model”
When requirements are clear, organization can follow waterfall model.
Explanation of above diagram:

1. From the above diagram at first software bidding will be done between the CEO of
   company and customer or client. Then after bidding, the CEO will conduct the
   meeting with all the project managers (PM) in the company called as “kick of
   meeting”(KIM).
2. In that meeting CEO will make an announcement about that new project to
   handle that project any one of the project manager will be selected. Then that
   project manager will give a project initiation note (PIN) to CEO.
3. Then PM will assign the work to the business analyst (BA) to gather all the
   requirements from the customer.
4. Then BA will submit all the gathered requirements to the system analyst (SA) to design in order to do the analysis or detailed planning which is going to submit it to the PM. Then PM will approve that planning done by SA.
5. Then SA will submit that document to the technical architect (TA).
6. Then designers will do the design which consists of HLD and LLD’s.
7. Based on that design programmers will do the coding and that corresponding programmers will test the developed code.
8. Then after testing that s/w few programmers will be selected for onsite and release the s/w.
9. Then change for control board (CCB) people will do the maintenance/support of that s/w.

Advantages of waterfall model:

1. The main strength of waterfall model is its simplicity and it is very easy to use.
2. Output generated at the end of each phase is reviewed and approved and hence
   it has high visibility.
3. Minimal resources are required.
4. It is less expensive as minimal resources are required.
5. This model is preferred for smaller projects where requirements are well clear.
6. Time spent early on making sure that requirements and design are absolutely
   correct saves much time and effort later.

Disadvantages of waterfall model:

1. It is difficult to implement any changes in the requirement.
2. No working software is produced until the last stage of the life cycle.
3. It is expensive to incorporate any changes once the project is in to testing phase.
4. Not suitable for complex projects, long term projects.
5. Not suitable when requirement are not clear.