4. INTRODUCTION
The spiral model was defined
by Barry Boehm in his 1988
article.
This model was not the first
model to discuss iterative
development, but it was the
first model to explain why the
iteration matters.
5. SPIRAL MODEL
Best for complex
embedded products
and changing
requirements
It supports risk
handling by
evaluating the risks in
each stage.
It is a combination of
waterfall model &
iterative model
The exact number of
loops of the spiral is
unknown and can
vary from project to
project.
Each loop of the
spiral is called a
phase of the software
development process.
6. KEY FEATURES OF THE
SPIRAL MODEL
Iterative and evolutionary : It develops software
in repeated cycles.
Risk management at every phase : It identifies
and mitigates risks early.
Customer involvement : continuous feedback and
requirement refinement.
Flexible and adaptable : It can accommodate
changes easily.
7. PHASES OF SPIRAL MODEL
Identification
Designing
Construction
Evaluation
The four quadrants of
spiral model;
8. IDENTIFICATION
This phase starts with gathering the
requirements.
This phase also includes understanding the
system requirements by continuous
communication between the customer and the
system analyst.
The objectives are identified, elaborated and
analyzed at the start of every phase.
9. DESIGNING
This involves architectural design, logical
design of modules, physical product design
and the final design in the subsequent spirals.
At the end of this quadrant.
Prototype is built.
10. CONSTRUCTION
This phase refers to production of the actual
software product.
The identified features are developed and
verified through testing.
At the end of the third quadrant, a new version
of the software is available.
These builds are sent to the customer for
feedback.
11. EVALUATION
In the fourth quadrant, the customers evaluate
the so far developed version of the software.
The software development process enters the
next iteration and subsequently follows the linear
approach to implement the feedback suggested
by the customer.
The process of iterations along the spiral
continues throughout the life of the software.
12. WHEN TO USE SPIRAL
MODE
When costs and risk evaluation is important
Users are unsure of their needs
Requirements are complex.
Significant changes are expected.
When deliverance is required to be frequent.
For large and long-term projects.
13. ADVANTAGES OF THE
SPIRAL MODEL
Effective risk management reduces failure
Early and frequent feedback from users
Flexible to changing requirements.
Encourages early testing and prototyping.
Works well for complex and high-budget
projects.
14. DISADVANTAGES OF
THE SPIRAL MODEL
Expensive due to continuous risk assessment.
Time-consuming because of multiple iterations.
Complex to manage compared to other models like
waterfall.
Not suitable for small projects with limited budgets.
Risk assessment expertise is required
End of project may not be known early
15. CONCLUSION
The spiral model is a
powerful methodology for
handling complex, risk-
prone projects.
It ensures continuous
improvement and
adaptability.
Best suited for projects
where risk assessment is a
priority.
