Spiral Model

The Spiral model is a Software Development Life Cycle (SDLC) that combines the Waterfall model and iterative development approaches. Each phase within this model involves risk analysis and prototyping.

The Spiral model was first introduced by Barry Boehm in 1986 as a result of applying iterative development in constructing software. It is divided into four phases:

1. Planning
2. Risk Analysis
3. Engineering
4. Evaluation

Each iteration consists of all above phases but has different aims which are usually:

• Prototype
• Release candidate
• Launch

Advantages

• Products are prototyped for quick introduction.
• Errors and failures are identified and handled as they arise.
• Frequent feedback and refinement through cycles.
• Flexible and adaptive to changes.

Disadvantages

• Complex workflow and requires expertise especially in risk analysis.
• Costly and time-consuming.