TRADITIONAL SOFTWARE DEVELOPMENT PROCESSES - Software Design for Six-Sigma: A Roadmap for Excellence - page 31

8. The final system is constructed, based on the refined prototype.
9. The final system is evaluated thoroughly and tested. Routine maintenance is
carried out on a continuing basis to prevent large-scale failures and to minimize
downtime.

2.3.1.6.1 Advantages

Decisive points of the project implementation strategies predefine the overall
project management framework by the logical sequencing of project completion.
This model of development combines the features of the Prototyping Model and
the simplicity of the Waterfall Model.

2.3.1.6.2 Disadvantages

It could become very costly and time consuming.

2.3.1.6.3 Suitability. This model for development is good for the prototyping or
importantly iterative process of prototyping projects. Although, the Spiral Model is
favored for large, expensive, and complicated projects (Watts, 1997), if practiced
correctly, it could be used for small- or medium-size projects and/or organization.

2.3.1.7 Chaos Model. In computing, the Chaos Model (2008) is a structure of
software development that extends the Spiral Model and the Waterfall Model. The
Chaos Model notes that the phases of the life cycle apply to all levels of projects,
from the whole project to individual lines of code.

The whole project must be defined, implemented, and integrated.
Systems must be defined, implemented, and integrated.
Modules must be defined, implemented, and integrated.
Functions must be defined, implemented, and integrated.
Lines of code are defined, implemented, and integrated.

One important change in perspective is whether projects can be thought of as
whole units or must be thought of in pieces. Nobody writes tens of thousands of lines
of code in one sitting. They write small pieces, one line at a time, verifying that the
small pieces work. Then they build up from there. The behavior of a complex system
emerges from the combined behavior of the smaller building block. There are several
tie-ins with chaos theory.

The Chaos Model may help explain why software tends to be so unpredictable.
It explains why high-level concepts like architecture cannot be treated indepen-
dently of low-level lines of code.
It provides a hook for explaining what to do next, in terms of the chaos strategy.