Spiral model

The above diagram (simplified for this course) shows the spiral model. The waterfall model is the simplest representation of the lifecycle while the spiral model is a much more compex version. It is a itterative model whilst the waterfall is more of a big bang approach. The spiral model is more suited to large projects whilst the waterfall model is more suited to the waterfall model.

The basic premise of the spiral model is risk analysis and iterative development. The project first of all has its requirements worked out through analysis. Once this has been done the risks are then looked at. This is a critical part of the model as large scale projects require large scale finance. If the risk of the project is too great then the project should be aborted. If the project goes ahead then a prototype is produced. This prototype is then evaluated by both the customer and the developer and new requirements drawn up.

Multiple prototypes are drawn up going through the exact same cylce, all building upon each other. It is possible to see each prototype as versions of software so each cycle could be a version.