Spiral Model

Spiral Model:

A VIDEO LECTURE ON SPIRAL MODEL

• Spiral model is an evolutionary software model.
• Spiral model may be viewed as a Meta model, because it can accommodate any process model.
• Spiral model focuses on identifying and eliminating high risk problems.

Following is the illustration of Spiral model:

• First Quadrant :It determine the objective and alternative solution possible for the phase under consideration.
• Second Quadrant: We evaluate different alternatives based on objective and constraint. To resolve risk.
• Third Quadrant: It emphasises development of strategies to resolve the uncertainties and risks.
• Fourth Quadrant: We determine the objective that should be full filled in next cycle to get complete system.

Characteristics of Spiral Model:
• It is cyclic not linear like Waterfall model.
• Each cycle of Spiral Model consist of four stages.
• Each stage is represented by quadrant of Cartesian Diagram.
• Radius of Spiral represent cost accumulated so far in the process.
• Angular dimension represent progress in process.

• It is risk driven model.
• It is very flexible.
• Less documentation is needed.
• It uses prototyping.
• It is more realistic model for software development.

• Not suitable for small projects.
• Cost is very high.
• Rely on risk assessment expertise.
• Excellent management skills needed.
• Involvement of different persons makes it complex too.

Limitations of Spiral Model:
• Software development has no strict standard.
• Particular phase has no particular beginning and end.

When to use Spiral Model:
• Spiral model is used when experimenting on technology.
• When trying out new skills.
• When the user is not able to offer requirements in clear terms.
• When system is very complex with lot of functions  and facilities.
• When requirements is not clear.
• When the intended solution has multi user, multi functions, multi features, multi locations applications to be used on multiple platforms.

1. Spiral model was developed by
a) Berry Boehm
b) Bev Littlewood
c) Victor Basili
d) Roger Pressman
Answer:a Spiral model was first described by Barry Boehm, in 1986, in his paper "A Spiral Model of Software Development and Enhancement"

2. Project risk factor is considered in ?
a. Spiral Model
b. Prototyping Model
C. Waterfall Model
d. Iterative enhancement Model

Spiral Model

3. In risk analysis of spiral model, which of the following risk includes ?
a. Technical
b. Management
c. None of these
d. Both A and B

4. The model remains operative until the software is retired ?
a. Waterfall
b. Spiral
c. Incremental
d. None of these