Spiral Model

Submitted To : Inam Ul-Haq Lecturer in Computer Science University of Education, Okara Campus

Submitted By:

Muhammad Yameen Shakir 3001

Faisal Islam Mujahid 3003 Course Name : Software Engineering

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Table of Contents

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Introduction History of Spiral Model Spiral Model PhasesImportance & ScopeAdvantages and Disadvantages of Spiral model Comparison b/w SM and WMEvaluation ConclusionReferences

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Spiral Model

The Spiral model is a software development process combining elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and bottom-up concepts.

The spiral model also

explicitly includes risk management within software development. Identifying major risks, both technical and managerial, and determining how to lessen the risk helps keep the software development process under control.

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Spiral Model The spiral model is based on

continuous refinement of key products for requirements definition and analysis, system and software design, and implementation (the code).

At each iteration around the cycle, the products are extensions of an earlier product. This model uses many of the same phases as the waterfall model, in essentially the same order, separated by planning, risk assessment, and the building of prototypes and simulations.

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History 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.

In 1988 Boehm published a similar paper to a wider audience

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Spiral Model Phases

• A spiral model has 4 phases described below:

Planning phase

Risk analysis phase

Engineering phase

Evaluation phase.

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Spiral Model diagram

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Planning Phase Requirements are studied and gathered.

Feasibility study 

Reviews and walkthroughs to streamline the requirements

Requirements understanding document

Finalized list of requirements.

The project is reviewed and a decision made whether

to continue with a further loop of the spiral.

If it is decided to continue, plans are drawn up for the next phase of

the project.

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Risk analysis phase

Requirements are studied and brain storming sessions are done to

identify the potential risks

Once the risks are identified , risk mitigation strategy is planned and

finalized

Document which highlights all the risks and its mitigation plans

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Engineering Phase

Actual development and testing if the software takes place in this

phase

Code

Test cases and test results

Test summary report and defect report.

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Evaluation phase.

Customers evaluate the software and provide their feedback and

approval

Features implemented document

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When to use spiral model ?

When the project is large.

Where the software needs continuous risk evaluation.

Requirements are a bit complicated and require continuous

clarification.

Software requires significant changes.

Where enough time frame is their to get end user feed12back.

Where releases are required to be frequent.

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When to use spiral 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.

New product line.

Users are unsure of their needs.

Requirements are complex.

Significant changes are expected (research and exploration).

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Advantages of SM Development is fast

Larger projects / software are created and handled in a strategic way

Risk evaluation is proper.

Control towards all the phases of development.

More and more features are added in a systematic way.

Software is produced early.

Has room for customer feedback and the changes are implemented faster. Risk reduction mechanisms are in place. Supports iteration and reflects real-world practices –

Systematic approach

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Disadvantages of SM

Risk analysis is important phase so requires expert people.

Is not beneficial for smaller projects.

Spiral may go infinitely.

Documentation is more as it has intermediate phases.

Complex, relatively difficult to follow strictly.

Applicable only to large systems

It is costly for smaller projects.

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Comparison

Spiral Model

Risk factors are considered. The requirements are not

freeze. works in loop. costly as Risk factor is

covered. Better communication

between developer and customer.

Waterfall model

Risk factors are not considered.

The requirements are freeze. Is linear sequential model. Not much costly.

Communication level is not high

Comparison

Spiral Model

Number of phases is not fixed.

Used when requirement is not clear and needs conformation

customer interaction continuous to move together.

Risk factor is considered

prototype model

Number of phases is fixed.

Requirement are clear but

complex.

Customer interaction needs till

the prototype is app.

Risk factor are not considered

Summary

• The Spiral Development ( or Lifecycle) Model is a systems development method used in information technology.

• It combines the features of the prototyping model and the waterfall model.

• It is favored for large, expensive, and complicated models.

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Conclusion

Each spiral can be termed as a loop and each loop is a separate development process in a spiral model.

The four activities (Planning, Risk analysis, engineering and evaluation) form the intermediary phases of a spiral model and is repeated again for each loop.

This model is very good to use for larger projects where you can develop and deliver smaller prototypes and can enhance it to make the larger software.

The implementation of this model requires experienced resources as risk analysis is a very integral part of this model and risk analysis requires expertise and as a result this model becomes costly.

References

http://www.tutorialspoint.com/sdlc/sdlc_spiral_model.htm

Advantages and disadvantageso http://www.technotrice.com/what-is-spiral-model-

software-engineering/Introduction , historyo http://en.wikipedia.org/wiki/Spiral_modelo http://robincse.blogspot.comWhat is spiral model and when to useo http://www.softwaretestinghelp.com/spiral-model-what-

is-sdlc-spiral-model/o boehms-spiral-process-model.html

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Best of Luck for Future

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