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Chapter 4. Measuring Evolving Software
Abbv. Name Description
ODC Out Degree Count Number of classes that this class depends
upon. Metric is defined by
l out (n) and the values are within the
interval [0, |K|).
IDC In Degree Count Number of classes that depend on
this class. Metric is defined by l in (n)
and the values are within the interval
[0, |N|).
EDC External Out Degree
Count
Number of classes that this class
classes depends upon, but belong in
external libraries. Metric is defined
by lout e (n) and the values are within
the interval [0, |K|).
TDC Internal Out Degree
Count
Number of classes that depend on
this class and are part of the core
software system. Metric is defined by
lout i (n) and the values are within the
interval [0, |N|).
Table 4.5: Dependency metrics computed for each class.
l out (n) = |{(n, n j ) ∧ n j ∈ K ∧ n ̸= n j }| (4.5.2)
The In-Degree Count is a measure of the “popularity" of node n in the
graph G T whereas the Out-Degree Count is node n’s “usage" of other
types in the graph G T [223].
We further refine the notions of in-degree and out-degree in the context
of our analysis by considering dependencies to classes in external
libraries. These external dependencies give rise to a refinement of the
measures in-degree and out-degree in which we also distinguish between
intra- and inter-system links. A given link to or from a node n
may or may not cross the boundary of the containing core system, depending
on some organizational, structural, and/or functional features.
If an outbound link from node n ends in a node n int that occurs within
the boundary of the system under analysis, then we call this link an
internal outbound link. On the other hand, if an outbound link ends
in a node n ext that lies outside of the system’s boundary, then we call
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