thesis - Faculty of Information and Communication Technologies ...

Chapter 2. Software Evolution
The questions related to growth that we address in this thesis are:
• What is the nature of distribution of size and complexity measures?
• How does the profile and shape of this distribution change as software
systems evolve?
• Do large and complex classes become bigger and more complex as
software systems evolve?
The questions related to change that we address in this thesis are:
• What is the likelihood that a class will change from a given version
to the next?
• How is modification frequency distributed for classes that change?
• What is the distribution of the size of change? Are most modifications
minor adjustments, or substantive modifications?
• Does complexity make a class change-prone?
Our study address the gaps in the current literature by investigating
the evolution in forty non-trivial object-oriented Java software systems.
The larger data set, as well as the consistent measures that we apply
across 1057 releases under investigation in our study increases
the strength of our conclusions. We analyse growth across a range
of different measures and focus on how growth is distributed across
the various classes. Furthermore, our study focuses on understanding
post-release changes which have a relatively higher risk profile.
The next chapter (Chapter 3) presents the input data set, our selection
criteria and the aspects that we investigate. Chapter 4 (Measuring Java
Software) follows with a discussion of the metric extraction process and
defines the metrics we collect from the Java software systems. The key
findings of this thesis are presented in Chapter 5 (Growth Dynamics)
and Chapter 6 (Change Dynamics). We discuss the implications arising
from our findings in Chapter 7 and conclude in Chapter 8.
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