Waterfall model

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Original at: http://www.rootsitservices.com/pictures/waterfall%20copy.jpg

This methodology of software development was one of the first to be implemented in order to have well made software.

In this model, all of the development of software is sliced in different steps, implemented one followed by another, always focused in different phases of the software development process. This phases are seperated to follow a sequential line. In other words, the process of Software development is sequantially.

Each of the phases means one different step:

  • Requirement and analysis: All possible requirements of the system to be developed are captured in this phase and documented in a requirement specification doc.
  • Design: The requirement specifications from first phase are studied in this phase and system design is prepared. System Design helps in specifying hardware and system requirements and also helps in defining overall system architecture.
  • Coding: With inputs from 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.
  • 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.
  • 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.

 

The following table lists out the pros and cons of Waterfall model:

Pros Cons
  • Simple and easy to understand and use
  • Easy to manage due to the rigidity of the model . each phase has specific deliverables and a review process.
  • Phases are processed and completed one at a time.
  • Works well for smaller projects where requirements are very well understood.
  • Clearly defined stages.
  • Well understood milestones.
  • Easy to arrange tasks.
  • Process and results are well documented.
  • No working software is produced until late during the life cycle.
  • High amounts of risk and uncertainty.
  • Not a good model for complex and object-oriented projects.
  • Poor model for long and ongoing projects.
  • Not suitable for the projects where requirements are at a moderate to high risk of changing. So risk and uncertainty is high with this process model.
  • It is difficult to measure progress within stages.
  • Cannot accommodate changing requirements.
  • Adjusting scope during the life cycle can end a project.
  • Integration is done as a “big-bang. at the very end, which doesn’t allow identifying any technological or business bottleneck or challenges early.
Retrieved from: http://www.tutorialspoint.com/sdlc/sdlc_waterfall_model.htm
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