Connectivity properties of the Apache Ant class collaboration network

Properties of networks whose nodes represent classes of an object-oriented (OO) system, and links denote dependencies between them, are fundamental to understand, describe and characterize software complexity at the structural level. In this paper, degree distributions of the class collaboration network that represents class dependencies of Apache Ant software were examined. In contrast to similar studies where complementary cumulative degree distributions were tested only against a power law, here we also consider the exponential distribution. Our analysis revealed scale-free phenomena in in-degree and total degree distributions. However, Ant's out-degree sequence is better modeled with the exponential distribution than a power law. Based on this result, implications relevant to software engineering are discussed in the aspect of the absence of a characteristic scale of class reuse and the presence of a characteristic scale of class aggregation.