Spiral Model, advantages and disadvantages of spiral model in software engineering

By: Prof. Fazal Rehman Shamil
Last modified on January 31st, 2021

Spiral Model, advantages and disadvantages of the spiral model in software engineering.

What is a spiral model?

The spiral model is a combination of waterfall, incremental, iterative and prototype model. It is mostly used for big projects where continuous changes are required.

Phases of the spiral model

  1. Planning
  2. Risk analysis
  3. Engineering and Construction
  4. Evaluation
Phase Activities Deliverable
Planning Requirement gathering

Requirement analysis

Requirement specification

Requirement negotiation

Requirement modeling

Requirement Management

Software Requirement Specification document

(SRS)

Risk Analysis Risk identification

Prioritization of risk

Risk reduction (Mitigation)

Risk impact reduction

Risk monitoring

 

Risk detailed document
Engineering Development

Testing

Code

Test cases document, Test report document

Fault report document

Evaluation Initial Validation by stakeholders

Final Validation by customer 

Evaluation report document

 

What are the advantages of the spiral model?

Ensure risk reduction

Useful for large projects

Changes can be handled in the next iteration/loop.

Most suitable for real-time systems

What are the disadvantages of the spiral model?

Expert required for risk reduction

More costly

 Not suitable for small projects

 Project duration can be infinite because of its spiral behavior.

Project cost can be infinite because of its spiral behavior

 Documentation can be very large

arial, helvetica, sans-serif;”> Not suitable for the projects with low risk

When to use the spiral model?

When the risk is medium or high

When software is to be used in a very sensitive and dangerous environment.

 For real-time systems

 For large projects

 When requirements are not clear

 When changes in the software can be expected at any time.

Comparison of SDLC Models

Comparison of  spiral model and waterfall model

Properties Spiral Waterfall
Objectives High Assurance High Assurance
Planning in early stage Yes Yes
Returning to an earlier phase Yes No
Handle Large-Project Appropriate Not Appropriate
Time-Frame Long Very Long
Working software availability At the end of every iteration At the end of the life-cycle
Risk Involvement Medium to high risk High
Software Team size Large Software Team Large Software Team
Customer control over administrator Yes Very Low
Maintenance Typical Least
Time Duration Long Long
Re-usability To some extent Least possible
Framework Type Linear + Iterative Linear
When Testing? At the end of the engineering phase After completion of development phase
Maintenance Yes Least Maintainable
Detailed Documentation Yes Necessary
Overlapping Phases No No

 

Comparison of  spiral model and incremental model

Properties Spiral Incremental
Objectives High Assurance Rapid Development
Planning in early stage Yes Yes
Returning to an earlier phase Yes Yes
Handle Large-Project Appropriate Not Appropriate
Time-Frame Long Long
Working software availability At the end of every iteration At the end of every iteration
Risk Involvement Medium to high risk Low
Software Team size Large Software Team Not Large Software Team
Customer control over administrator Yes Yes
Maintenance Typical Promotes Maintainability
Time Duration Long Very long
Re-usability To some extent To some extent
Framework Type Linear + Iterative Linear + Iterative
When Testing? At the end of the engineering phase After every iteration
Maintenance Yes Maintainable
Detailed Documentation Yes Yes but not much
Overlapping Phases No Yes

 

Comparison of  spiral model and RAD

Properties Spiral Rad
Objectives High Assurance Rapid development
Planning in early stage Yes No
Returning to an earlier phase Yes Yes
Handle Large-Project Appropriate Not Appropriate
Time-Frame Long Short
Working software availability At the end of every iteration At the end of the life cycle
Risk Involvement Medium to high risk Low
Software Team size Large Software Team Small Software Team
Customer control over administrator Yes Yes
Maintenance Typical Easily Maintained
Time Duration Long Short
Re-usability To some extent Yes
Framework Type Linear + Iterative Linear
When Testing? At the end of the engineering phase After completion of development
Maintenance Yes Easily Maintainable
Detailed Documentation Yes Limited
Overlapping Phases No Yes

More MCQs on Software Process Models

  1. Iterative Model MCQs
  2. Spiral Model MCQs
  3. incremental Model MCQs
  4. Software Process Models MCQs

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Prof. Fazal Rehman Shamil