thesis - Faculty of Information and Communication Technologies ...

Chapter 4. Measuring Evolving Software
of Inheritance Tree to have a value of 1. However, if the Java framework
was fully analysed then this would change to 6 (for Java 1.6), since we
now are processing the full extent of the inheritance chain by extracting
additional information from the external Java framework. Though our
metrics are constrained, the inheritance hierarchy within the external
framework was designed and created by an external team and hence all
changes to it are outside of the direct control of the development team
creating the software under study. Hence, we do not measure the inheritance
hierarchies of external libraries and the core Java framework as
part of our analysis. Furthermore, we do not consider interface implementation
as inheritance and hence do not count them in our metrics.
4.6 Summary
The evolution of a software system can be studied in terms of how various
properties as reflected by software metrics change over time. We
build a release history model by analysing the compiled class files. Our
release history model captures meta-data and 58 different metrics at a
class level. We also build a class dependency graph for each release in
the evolution history.
The data selection and metric extraction method that we use ensures
that we study non-trivial software allowing us to extend our findings
to other comparable software systems built in Java. We also analyse
compiled binaries that have already gone through the build process
improving the accuracy of our measures. Further, as discussed in the
previous chapter, we focus on contributions from the core development
team ignoring third party libraries ensuring that the metrics that we
collect are a better reflection of the development effort.
The next chapter (Growth Dynamics) addresses the research questions
related to growth. We describe how size and complexity is distributed
as systems evolve and present a novel analysis technique to help understand
growth dynamics.
89