The Spiral Model

The Spiral Model

• Proposed by Barry Boehm.
• Spiral model is an evolutionary software process model that couples the iterative nature of prototyping with the controlled and systematic aspects of the waterfall model.
• It provides the potential for rapid development of increasingly more complete versions of the software
• A risk-driven process model generator that is used to guide multi-stakeholder concurrent engineering of software intensive systems.
• Two Fetures of spiral model.
• 1.Cyclic
• Incrementally growing a system's degree of definition and implementation while decreasing its degree of risk.
• 2.Anchor Point Milestones
• Assure that stakeholder commitment to feasible and mutually satisfactory system solutions.
• divided into a set of framework activities defined by the software engineering team.
• evolutionary process begins, the software team performs activities that are implied by a circuit around the spiral in a clockwise direction, beginning at the center.
• Risk is considered as each revolution.
• A combination of work products and conditions that are attained along the path of the spiral—are noted for each evolutionary pass.
• Each pass results in adjustments to the project plan.Cost and schedule are adjusted based on feedback derived from the customer.
• The spiral model is a realistic approach to the development of large-scale systems and software.
• The spiral model is not a solution.
• Difficult to convince customers that the evolutionary approach is controllable.
• If a major risk is not uncovered and managed, problems will undoubtedly occur.