1. Spiral Model For Software Development By : Sumeet Singh Roll No. : 23 Reg No. : 40080120

2. Software development The set of activities that results in software products. Software development may include research, new development, modification, reuse, re-engineering, maintenance, or any other activities that result in software products. Especially the first phase in the software development process may involve many departments, including marketing, engineering, research and development and general management.softwaremarketingengineering research and development management

3. Requirement Analysis Design Specification Architecture Implementation, testing and documenting Deployment and maintenance Software development activities `

4. Introduction The spiral model of s/w development and enhancement presented here provides a new framework for guiding the s/w process, rather than a strictly specification-driven or prototype driven process. It incoprates many of the strengths of other models, while resolving many of their difficulties

5. Background Earliest s/w process models is the stagewise model given in 1958. Then came Waterfall Model in 1970 Then came spiral model in 1976.

6. Stage wise model S/W To be developed in successive stages like operational plan,operational specification, coding specification, coding, parameter testing, assembly testing, shake down, system spec.

7. Waterfall model Consistent with top-down structured programming model. The original treatment of the waterfall model provided 2 primary enhancements to the stage wise model 1) Recognition of the feedback loops b/w the stages, and a guideline to confine the feedback loops to successive stages in order to minimize the expensive rework involved in many stages. 2) An initial incorporation of prototyping in the s/w lifecycle.

8. Difficulties with waterfall model 1) The build it twice step was unnecessary in some situations. 2) The pure top down approach need to be tempered in some situations

9. Alternate S/W Life Cycle models Parnas- Has Information hiding approach. Two-leg model-Separate Process of abstraction until a formal specification is achieved. Evolutionary & Mixed Models-Rapid Prototyping Approach Automation Paradigim-Adress the possible future models of S/W development associated with automatic program cpabilities, program tranformation capabilities and knowledge based S/W assistant capabilities.

10. Challenges to alternate models Parnas-Information hiding approach has yet not fully elaborated to see how will it cover issues like prototyping and reuse of previous models. Two-leg model- challenge in accommodating S/W reuse, program famalies and logical and physical design tradeoffs. Evolutionary development approach- scaling upto very large systems, ensuring process viability and control. Automation Paradigm- Scaling upto very large systems accomodating program famalies, handling choices b/w older, stable but less powerful capabilities and new unstable but more powerful capabilities.

11. Reasons for the proposal of spiral model there is no fair division of phases in the life cycle, not all the errors/problems related to a phase are resolved during the same phase, instead all those problems related to one phase are carried out in the next phase and are needed to be resolved in the next phase, this takes much of time of the next phase to solve them. The risk factor is the most important part, which affects the success rate of the software

13. Spiral Model for software Development Cycle 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.software development processdesignprototypingtop-down and bottom-up

14. Figure Representation Radial dimension represent cost incurred in accomplishing the step and the angular dimension represent the progress made in completing each cycle of the spiral.

15. First Step The objectives of the portion(performance, functionality, ability to accommodate the change) Alternative means of implementing this portion of the product(design A,B, resuse etc) Constraints imposed on the application of the alternatives(cost, schedule, interface etc)

16. Second step Evaluate the alternatives with respect to objectives and constraints. This step will identify the risk. If so, cost-effective strategy for resolving the source of risk.

17. Third Step Once the risks are evaluated the next step is deteminted by the relative risks remaining i.e performance, userinterferance risk, internal interferance control risk. These risks are resolved by developing more detailed prototyping. Spiral model also accomodates any appropriate mixture of specification-oriented, prototype-oriented, simulation-oriented, automatic tranforamntion-oriented or other approaches to software s/w development where appropriate mixed stratergy is chosen by considering the relative magnitide of the risk involved.

18. Spiral Model Features

19. Advantages The spiral model is a realistic approach to the development of large-scale software products because the software evolves as the process progresses. In addition, the developer and the client better understand and react to risks at each evolutionary level. The model uses prototyping as a risk reduction mechanism and allows for the development of prototypes at any stage of the evolutionary development. It maintains a systematic stepwise approach, like the classic life cycle model, but incorporates it into an iterative framework that more reflect the real world. If employed correctly, this model should reduce risks before they become problematic, as consideration of technical risks are considered at all stages.

20. Risk Management

21. Software Risk Management Plan

22. Conclusions

23. Discussion

24. Thanks for bearing me for a long time.