Independent on-line monitoring of evolving systems

We argue that the trustworthiness of evolving software systems can be significantly enhanced by a rigorous process of independent on-line monitoring. Such monitoring can prevent fraud, encourage careful maintenance, and serve as an early detector of irregularities in the state and behavior of a system. Unfortunately, there is a conflict between the concepts of on-line and independent monitoring. This conflict is due to the fact that on-line monitoring requires the embedding of some kinds of sensors in the base-system. But the introduction of such sensors requires a degree of cooperation with the developers of the base system, and may interfere with the operations of that system, contrary to the requirements of independent monitoring. We describe a way to resolve this conflict by applying the concept of law-governed architecture.