Waterfall Model

1.    The waterfall model is also called as “Linear-sequential Model” or “Classic Life Cycle Model”. It is the oldest software paradigm. This model suggests a systematic, sequential approach to software development.

2.    The software development starts with requirements gathering phase. Then progresses through analysis, design, coding, testing and maintenance.

3.    In requirement gathering and analysis phase the basic requirements of the system must be understood by software engineer, who is also called Analyst. The information domain, function, behavioural requirements of the system are understood.

4.    The design is an intermediate step between requirements analysis and coding.

            Design focuses on program attributes such as:

1.    Data structure

2.    Software architecture

3.    Interface representation

4.    Algorithm details

5. Coding is a step in which design is translated into machine-readable form. Programs are created in this phase.

6.     Testing begins when coding is done. The testing ensures execution of all the paths, functional behaviours. The purpose of testing is to uncover errors, fix the bugs and meet the customer requirements.

7.    Maintenance is the longest life cycle phase. When the system is installed and put in practical use then error may get introduced, correcting such errors and putting it in use in the major purpose of maintenance activity. Similarity enhancing system’s services as new requirements are discovered is again maintenance of the system.

This model is widely used model, although it has many benefits and drawbacks.

Benefits of waterfall model

1.    The waterfall model is simple to implement.

2.    For implementation of small systems waterfall model is useful.

Drawbacks of waterfall model

1.    It is difficult to follow the sequential flow in software development process. If some changes are made at some phases then it may cause some confusion.

2.    The requirement analysis is done initially and sometimes it is not possible to state all the requirements explicitly in the beginning. This causes difficulty in the project.

3.    The customer can see the working model of the project only at the end. After reviewing of the working model; if the customer gets dissatisfied then it causes serious problems.

4.    Linear nature of waterfall model induces blocking states, because certain tasks may be dependent on some previous tasks. Hence it is necessary to accomplish all the dependent tasks first. It may cause long waiting time.