thesis - Faculty of Information and Communication Technologies ...
thesis - Faculty of Information and Communication Technologies ...
thesis - Faculty of Information and Communication Technologies ...
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Chapter 4. Measuring Evolving S<strong>of</strong>tware<br />
The classes that we measure are compiled Java classes <strong>and</strong> our metric<br />
extraction approach is discussed in Section 4.5.2. The class dependency<br />
graph captures the dependencies between the various classes in<br />
the s<strong>of</strong>tware system. The graph is constructed by analysing all classes<br />
in the system <strong>and</strong> our method is discussed in further detail in Section<br />
4.5.4 <strong>and</strong> Section 4.5.5. We consider the metrics that are described<br />
in this chapter as direct metrics since we compute the value by a direct<br />
count <strong>of</strong> either a class or a graph, rather than by combining different<br />
types <strong>of</strong> measures. That is, the domain used by the metric function<br />
contains only one variable.<br />
4.2 Types <strong>of</strong> Metrics<br />
S<strong>of</strong>tware systems exhibit two broad quantitative aspects that are captured<br />
by a range <strong>of</strong> s<strong>of</strong>tware metrics: size <strong>and</strong> structural complexity [77].<br />
These metrics can be used to provide a quantitative view <strong>of</strong> the s<strong>of</strong>tware<br />
systems size <strong>and</strong> internal structure as well as infer the process<br />
being used to create the s<strong>of</strong>tware system [117]. Over the past few<br />
decades, a number <strong>of</strong> different s<strong>of</strong>tware metrics have been proposed<br />
(e.g., purely size-oriented measures like the number <strong>of</strong> lines <strong>of</strong> code<br />
(LOC) or function-oriented measures to analyze process aspects like<br />
costs <strong>and</strong> productivity) to aid in the comprehension <strong>of</strong> the size as well<br />
as the complexity <strong>of</strong> a s<strong>of</strong>tware system [77,165]. When these measures<br />
are collected <strong>and</strong> analyzed over time, we can distil a temporal dimension<br />
which is capable <strong>of</strong> revealing valuable information such as the rate <strong>of</strong><br />
change [174,175] <strong>and</strong> evolutionary jumps in the architecture <strong>and</strong> complexity<br />
<strong>of</strong> the s<strong>of</strong>tware system under observation [101]. In this <strong>thesis</strong>,<br />
we collect both size <strong>and</strong> complexity metrics at the class level as this is<br />
the primary abstraction under study in our work.<br />
4.2.1 Size Metrics<br />
Size measures provide an indication <strong>of</strong> the volume <strong>of</strong> functionality provided<br />
by a s<strong>of</strong>tware system. Size metrics are considered to be a broad<br />
indicator <strong>of</strong> effort required to build <strong>and</strong> maintain a s<strong>of</strong>tware system,<br />
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