Spiral model

                                 Spiral Model: 

This dummy(model) can be considered as the model, which combines the strengths of assorted other models.
The spiral model blends the idea of iterative development with the systematic, controlled aspects of the waterfall model.
This Spiral model is a merger of iterative development process model and sequential linear development model i.e. the waterfall model with a very high attention on risk analysis. It allows incremental releases of the product or incremental refinement over each iteration around the spiral.

Spiral model = Iterative model + process model + waterfall model 

Spirals 

The spiral model has four phases. A software project repeatedly passes through these phases in iterations called Spirals.

Identification:-  

This phase outset with gathering the business requirements in the baseline spiral. In the successive spirals as the commodity matures, identification of system requirements,subsystem requirements and unit requirements are all done in this aspect.

Design:- 

The Design phase dawn with the conceptual design in the baseline spiral and involves architectural design, logical design of modules, physical product design and the final design in the consecutive spirals.

Construct or Build:- 

The Construct phase indicate 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 (Proof of Concept) is expansion in this phase to get customer feedback.


        Then in the successive spirals with higher lucidity on requirements and design details a working domain of the software called frame is produced with a version figure. These builds are sent to the customer for evaluation.

Evaluation and Risk Analysis:- 

Risk Analysis build identifying, estimating and audit the technical feasibility and management risks, such as slate slippage and cost overrun. After testing the build, at the end of early iteration, the customer evaluates the software and afford feedback.