What is Spiral Model in Software Engineering?

Spiral Model is a progressive software approach that pairs the iterative component of prototyping with the controlled and methodical characteristics of the linear sequential model. It executes the possibility for quick development of newer versions of the software. Through the spiral model, the software is designed and executed in a string of incremental releases. In the earlier iterations, it may be a document model or prototype. In later iterations, a complete version is developed.

Phases of Spiral Model

Spiral Model can be described in four phases as follow:

Goal Identification:

This phase begins with understanding business requirements in a baseline spiral. In the following spirals, as the product develops, the following are identified:

• System requirements
• Subsystem requirements
• Unit requirements

This phase also contains learning system requirements through continuous communication between customers and system analysts. At the end of the spiral, the product is used in the specified market.

Design

The design phase begins with the conceptual design of the basic spiral and includes the following:

• Architectural design
• The logical design of the module
• The physical product design
• The final design of the next spiral

Development

This phase directs to the development of the software product for each spiral. In the baseline spiral, if you develop your design with the product in mind, POCproof of concept is designed during this phase to receive client review. In the next spiral, which clarifies the requirements and structural details, a behavioral model of the software called a build is created by version number. These builds are delivered to the client for review.

Evaluation

This phase includes specifying, evaluating, and observing the technical achievability and management risks, like the following:

• Schedule slippage
• Cost overrun

The client assesses the software and gives feedback after the end of the first iteration testing.

When to use Spiral Model

Below are some of the scenarios when we would use the Spiral Model:

Advantages of Spiral Model

The benefit of the Spiral model is that you can add a product element that becomes functional or known. This eliminates conflicts with earlier requirements and designs. This methodology is compatible with an approach that involves multiple software builds and releases, enabling a tidy transition to maintenance activities. It also forces users to get involved at all stages.

• Requirements can be changed later on
• Risk analysis is high
• Used for large projects
• Development can be done in smaller modules

Disadvantages of Spiral Model

Making products requires very strict control and there is a chance that the spiral will loop indefinitely. Therefore, the domain of change and the degree to which change requests are recorded is very necessary for successful product development and deployment.

• Managing may become difficult
• Final stage of the product may be not identified earlier
• Difficult processing
• Excessive Documentation is required for some steps