Software Evolution and the Constructal Law

This chapter investigates the evolution in time of the number of lines of the Java source code of the Java Development Kit (JDK). We show that the rank-size distributions of the JDK source files developed characteristic evolutionary patterns during the last fifteen years, such as parabolic fractal distributions, and a sigmoid shape of the cumulated lines of code. In order to explain the emergence of these patterns, we propose here to consider the constructal tree-shaped invasion of a territory combined with the constructal rank-size distribution of a growing population as the mechanism potentially generating a wide variety of population distributions. In the case of the JDK, the functional scope addressed by the successive versions of the platform, assimilated to a functional space to invade, continuously increased in time. The development of the JDK‘s functional packages hierarchy is interpreted as the constructal tree-structure followed by the invasive flow. We propose in conclusion to consider the Constructal Law as the main driver behind software evolution.