The document discusses the spiral model of software development. The spiral model is an iterative approach that combines prototyping and aspects of the waterfall model. It was defined by Barry Boehm in 1988 as a way to address risks through iterative evaluation and improvement of prototypes. The spiral model is best for medium to high risk projects where requirements are complex or expected to change. It involves evaluating prototypes, defining new prototypes based on learnings, and repeating this process until the final product is delivered.

1. Sayed Farhan Ali Shah
BS(I.T) 5° semester P-3
RollNO: (39)
Subject: Introduction to software
development
Teacher: Sir Asadullah Kehar
Date:7/5/2014

2.  Spiral model is an evolutionary software process model which is a
combination of an iterative nature of prototyping and systematic aspects
of traditional waterfall model.

3.  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.

4. When costs and risk evaluation is important.
For medium to high-risk projects.
Users are unsure of their needs.
Requirements are complex.
Significant changes are expected.

5. 1. Evaluating the first prototype in terms of its
strengths, weaknesses, and risks.
2. Defining the requirements of the second
prototype
3. Planning and designing the second
prototype
4. Constructing and testing the second
prototype

6.  A prototype is an early sample, model or
release of a product built to test a concept or
process or to act as a thing to be replicated or
learned from.
6

7. PLAN Risk
Analysis
Customer Engineering
evaluation

8. The objectives, alternatives and constraints
of the project are determined and are
documented.

9.  All possible alternatives, which can help in
developing a cost effective project are
analyzed
This phase identify and resolve all the
possible risks in the project development.

10. The actual development of the project is
carried out
The output of this phase is passed through all
the phases iteratively in order to obtain
improvements in the same.

11. Developed product is passed on to the
customer in order to receive customer’s
comments and suggestions.
This phase is very much similar toTESTING
phase.

12.  The spiral model is used most often in large
projects.
 For smaller projects, the concept of agile
software development is becoming a viable
alternative.
 It is also reasonable to use the spiral model in
projects where business goals are unstable .

13.  Changing requirements can be
accommodated.
Allows for extensive use of prototypes.
Requirements can be captured more
accurately.
Users see the system early.
Early and frequent feedback from users.

14. End of project may not be known early.
Not suitable for small or low risk projects and
could be expensive for small projects.
Process is complex
Spiral may go indefinitely.
Risk assessment expertise is required.

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