The spiral model connects the thought of iterative development with the orderly, controlled phases of the waterfall model.
This spiral model is an aggregate of the iterative development model and incessant linear development paradigm, i.e., the waterfall model with some more stress on the risk identification.
It enables incremental builds of the product or continuous refinement through each repetition around the spiral.
Spiral Model – Design
The spiral model has four stages. A software plan repeatedly passes through these phases in repetitions called Spirals.
This stage begins with collecting the feature requirements in the baseline spiral. In the ensuing spirals as the product evolves, the discovery of system requirements, components info, and unit-level inputs occur in this phase.
This stage also involves learning the system requirements by constant communication between the client and the system analyst. At the end of the spiral, the software gets deployed in the unique market.
The Design phase begins with a basic thought of the mindmap in the first spiral and involves architectural design, logical layout of the modules, physical product prototype and the final design in the subsequent spirals.
The build stage refers to the production of the exact software product at every iteration. In the baseline cycle, when the software is just an idea of and the design is getting conceived as a prototype happens in this stage to learn client experience.
In the ensuing spirals with greater clarity on requirements and design specifications, a working copy of the software product known as build gets delivered with a proper version. It is then gets provided to the clients for their inputs.
4. Evaluation and Risk Analysis
Risk Analysis comprises classifying, measuring and observing the technical feasibility and business risks, such as schedule impact and cost escalations. After examining the build, at the end of the first repetition, the customer assesses the software and gives feedback.
The following model is a reflection of the Spiral Model, listing the actions in each stage.
Based on the client evaluation, the software development method enters the next iteration and consequently follows the direct approach to complete the feedback recommended by the customer. The process of iterations along the spiral lasts throughout the lifespan of the software.
5. Spiral Model Application
The Spiral Model is extensively used in the IT industry as it is in sync with the typical development method of any product, i.e., learning with maturity which comprises minimum uncertainty for the client and also for the development companies.
The following clues describe the typical uses of a Spiral Model.
1. When there is a funds constraint, and a risk assessment is necessary.
2. In the moderate to high-risk products.
3. Long-term project engagement because of possible changes to financial priorities as the requirements shift with time.
4. The client is not sure what they need in this case.
5. Conditions are complicated and need assessment to bring certainty.
6. Brand-new product line which must go to market in stages to get adequate client feedback.
7. Some core changes may occur in the product during the building phase.
Spiral Model – Pros and Cons
The plus point of the spiral model is that it enables components of the product to add when they are available or active. It eliminates any possibility of a conflict with any late requirements or the design.
This process is compatible with approaches that have multiple software builds and releases which permits forming an orderly shift to a maintenance exercise. Another unique aspect of this approach is that the spiral model requires an early user engagement in the system development exercise.
On the other side, it takes dogmatic management to conclude such products, and there is a gamble of going the spiral in an indeterminate loop. So, the system of change and the amount of taking change requests is critical to build and deploy the software favorably.
Here are a few of the strengths of the Spiral Model.
1. Evolving requirements can get accepted.
2. Welcome use of prototyping.
3. Feature requests have the accurate definition.
4. Early product builds are available.
5. Development can have subparts, and the development of the sensitive components happen earlier to minimize the risk involved.
Here are a few of the shortcomings of the Spiral Model.
1. Handling management tasks is tough.
2. Less clarity on the final stage of the project.
3. May not work for small or low-risk projects and raise the cost involved.
4. Process lifecycle is complicated.
5. Spiral may outrun the expected no. of iterations.
6. More are the phases, more get the need for product documentation.
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