Spiral model

 Topic Outline
  • Spiral Model
  • Planning
  • Risk Analysis
  • Engineering
  • Evaluation

Spiral Model

The spiral model was first mentioned by Barry Boehm, in 1986. The spiral model is also known as the spiral life cycle model is a systems development method used in information technology. The spiral model is more emphasis placed on risk analysis. Each phase begins with a design goal and ends with the client reviewing the progress.

When to use the Spiral model:

  • Spiral model is used when the project is large.
  • Spiral model is used when Requirements are complex.
  • Spiral model is used when cost and risk evaluation are important.
  • Spiral model is used for medium to high-risk projects

The four phases of the Spiral model are as follow:

Shape

Planning

In this phase software, analysts communicate with the client and the necessary requirements like Business Requirement Specification and System Requirement Specification are gathered. In planning, we estimate the cost and resources for iteration.

Risk Analysis

In this phase, analysts assume all the possible risks that could be occurred during future development, and alternative solutions are proposed to overcome future risks.

Engineering

This is the main phase of this model. Actual development and testing of the software take place in this phase. In this phase, the software is developed along with testing at the end of the phase. This phase includes testing, coding, and deploying software at the customer site.

Evaluation

This phase allows the customer to evaluate the output of the project to date before the project continues to the next spiral. Customers evaluate the software and provide their feedback and approval.

Advantages

  • Larger Projects
  • Development is fast
  • Larger projects
  • More features are added in a systematic way
  • Software is produced early

Disadvantages

  • Spiral goes infinitely
  • Spiral model is costly for smaller projects
  • In spiral model, risk analysis is an important phase so it requires expert people



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