Software Engineering Process Models:-Spiral Model:

Models/Factors	Waterfall	Prototype	Incremental	Spiral	Agile
Requirement Specification	Fixed	Dynamic	Fixed but large	Fixed	Serum sprint fixed
Customer Involvement	Nil/low	High	Low/High	High	Moderate
Duration	small	small	large	large	Large
Expertise	High	Moderate	High	Very High	High
Example	Ice cream	Big Project	It is done Part by Part	Every part    needs to be checked ex:maggi

Spiral Model:

Spiral Model was first described by Barry W. Boehm(American Software Engineer) in 1986. Spiral model works in an iterative nature. It is a combination of both Prototype development process and linear development process (waterfall model). This model place more emphasis on risk analysis. Mostly this model adopts to the large and complicated projects where risk is high. Every Iteration starts with a planning and ends with the product evaluation by client.

Let’s take an example of a product development team (like Microsoft). They know that there will be a high risk and they face lots of difficulties in the journey of developing and releasing the product and also they know that they will release next version of product when the current version is in existence. They prefer Spiral Model to develop the product in an iterative nature. They could release one version of the product to the end user and start developing next version which includes new enhancements and improvements on previous version (based on the issues faced by the user in the previous version). Like Microsoft released Windows 8 and improved it based on user feedback and released the next version (Windows 8.1).

Spiral Model undergoes 4 phases.

Planning Phase – Requirement Gathering, Cost Estimation, Resource Allocation

Risk Analysis Phase – Strengths and weaknesses of the project

Design Phase – Coding, Internal Testing and deployment

Evaluation Phase – Client Evaluation (Client side Testing) to get the feedback

Advantages:

·       It allows requirement changes

·       Suitable for large and complicated projects

·       It allows better risk analysis

·       Cost effective due to good risk management

Disadvantages:

·       Not suitable for small projects

·       Success of the project depends on risk analysis phase

·       Have to hire more experienced resource especially for risk analysis

When to use spiral process model?

·       When costs and risk evaluation is important for medium to high-risk projects.

·       Long-term project commitment unwise because of potential changes to economic priorities

·       Users are unsure of their needs.

·       Requirements are complex

·       New product line Significant changes are expected (research and exploration)