The Spiral Model, initially suggested by Bohem, is an evolutionary software process model that couples the iterative nature of prototyping with the controlled and systematic aspects of the linear sequential model. Using the Spiral model, the software is developed in order of incremental releases. It provides the potential for rapid development of incremental version of the software. A spiral model is divided into several framework activities also called task regions. Typically, there are between three & six task regions.
Customer communication- tasks required to establish effective communication between developer & customer.
Planning- Determination of objectives, alternatives, and constraints.
Risk Analysis- Analysis alternatives and attempts to identify and resolve the risks involved
Development- Product Development & Testing product
Each of the regions is populated by a set of work tasks called a task set, they are adapted to the characteristics of the project to be undertaken. For a small project, the number of work tasks and their formality is low. For a larger, more critical project, each task region contains more work tasks that are defined to achieve a higher level of formality.
When to use Spiral Model?