Software Design X-Rays

Measure Technical Sprawl

Four decades ago, Manny Lehman started documenting a series of observations on how software evolves, and his writings became known as Lehman’s laws. (See On Understanding Laws, Evolution, and Conservation in the Large-Program Life Cycle [Leh80].) One of the laws states the need for conservation of familiarity, which means that everyone involved in the life cycle of a system must maintain a working knowledge of the system’s behavior and content.

The main reasons for diminishing knowledge of a system are high turnover of personnel and, as Lehman points out, excessive growth of the codebase. However, microservices present another challenge that may hinder both collaboration and knowledge sharing, so let’s explore that. ...