The spiral model combines the idea of iterative development with the systematic, controlled aspects of the waterfall model. Spiral model is a combination of iterative development process model and sequential linear development model i.e.... more
The spiral model combines the idea of iterative development with the systematic, controlled aspects of the waterfall model. Spiral model is a combination of iterative development process model and sequential linear development model i.e. waterfall model with very high emphasis on risk analysis. It allows for incremental releases of the product, or incremental refinement through each iteration around the spiral. Spiral Model design The spiral model has four phases. A software project repeatedly passes through these phases in iterations called Spirals. Identification:This phase starts with gathering the business requirements in the baseline spiral. In the subsequent spirals as the product matures, identification of system requirements, subsystem requirements and unit requirements are all done in this phase. This also includes understanding the system requirements by continuous communication between the customer and the system analyst. At the end of the spiral the product is deployed in the identified market. Design:Design phase starts with the conceptual design in the baseline spiral and involves architectural design, logical design of modules, physical product design and final design in the subsequent spirals. Construct or Build:Construct phase refers to production of the actual software product at every spiral. In the baseline spiral when the product is just thought of and the design is being developed a POC ProofofConcept is developed in this phase to get customer feedback. Then in the subsequent spirals with higher clarity on requirements and design details a working model of the software called build is produced with a version number. These builds are sent to customer for feedback. Evaluation and Risk Analysis:Risk Analysis includes identifying, estimating, and monitoring technical feasibility and management risks, such as schedule slippage and cost overrun. After testing the build, at the end of first iteration, the customer evaluates the software and provides feedback. Following is a diagrammatic representation of spiral model listing the activities in each phase:
