Software Engineering - Old Questions

2. Explain the waterfall model with its merits and demerits.

6 marks | Asked in 2068(II)

The waterfall model is a sequential approach, where each fundamental activity of a process represented as a separate phase, arranged in linear order. Each phase is carried out completely (for all requirements) before proceeding to the next. The process is strictly sequential - no backing up or repeating phases. This SDLC model includes gradual execution of every stage completely. This process is strictly documented and predefined with features expected to every phase of this SDLC model.

SDLC – Lawrence's A-Level Computer Science

Fig: The waterfall model

The sequential phases in Waterfall model are −

1. Requirement Gathering and analysis − All possible requirements of the system to be developed are captured in this phase and documented in a requirement specification document.

2. System Design − The requirement specifications from first phase are studied in this phase and the system design is prepared. This system design helps in specifying hardware and system requirements and helps in defining the overall system architecture.

3. Implementation − With inputs from the system design, the system is first developed in small programs called units, which are integrated in the next phase. Each unit is developed and tested for its functionality, which is referred to as Unit Testing.

4. Integration and Testing − All the units developed in the implementation phase are integrated into a system after testing of each unit. Post integration the entire system is tested for any faults and failures.

5. Deployment of system − Once the functional and non-functional testing is done; the product is deployed in the customer environment or released into the market.

6. Maintenance − There are some issues which come up in the client environment. To fix those issues, patches are released. Also to enhance the product some better versions are released. Maintenance is done to deliver these changes in the customer environment.

Merits of Waterfall model

  • This model is simple to implement also the number of resources that are required for it is minimal.
  • The requirements are simple and explicitly declared; they remain unchanged during the entire project development.
  • The start and end points for each phase is fixed, which makes it easy to cover progress.
  • It gives easy to control and clarity for the customer due to a strict reporting system.
  • Easy to manage due to the rigidity of the model. Each phase has specific deliverables and a review process.

Demerits of Waterfall model

  • No working software is produced until late during the life cycle.
  • In this model, the risk factor is higher, so this model is not suitable for more significant and complex projects.
  • This model cannot accept the changes in requirements during development.
  • It becomes tough to go back to the phase.
  • Since the testing done at a later stage, it does not allow identifying the challenges and risks in the earlier phase, so the risk reduction strategy is difficult to prepare.