Metrics and laws of software evolution

Abstract

The process of E-type software development and evolution has proven most difficult to improve, possibly due to the fact that the process is a multi-input, multi-output system involving feedback at many levels. This observation, first recorded in the early 1970s during an extended study of OS/360 evolution, was recently captured in a FEAST (Feedback, Evolution And Software Technology) hypothesis: a hypothesis being studied in on-going two-year project, FEAST/1. Preliminary conclusions based on a study of a financial transaction system-Logica's Fastwire (FW)-are outlined and compared with those reached during the earlier OS/360 study. The new analysis supports, or better does not contradict, the laws of software evolution, suggesting that the 1970s approach to metric analysis of software evolution is still relevant today. It is hoped that FEAST/1 will provide a foundation for mastering the feedback aspects of the software evolution process, opening up new paths for process modelling and improvement.