Spiral Model

Typical Cycle of the Spiral

• Identification of
  • objectives (of the portion of the product being elaborated)
  • alternative means of implementing this portion of the product (design A, design B, buy)
  • constraints imposed on the application of the alternatives (cost, schedule, copyright)
  
  
  
• Evaluate the alternatives relative to the objectives and constraints
  • Identify areas of uncertainty that are significant sources of risk
  • Evaluate the risks (e.g., by prototyping, simulation, benchmarking)
  
  
  
• The next step is determined by the relative remaining risks. Each level of software specification and development is followed by a validation step.
  
  
  
• Each cycle is completed by the preparation of plans for the next cycle and a review involving the primary people or organizations concerned with the product. The review's major objective is to ensure that all concerned parties are mutually committed to the approach for the next phase.

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