Resilience is the ability to absorb disturbances, to be changed and then to re-organise and still have the same identity (retain the same basic structure and ways of functioning). It includes the ability to learn from the disturbance. A resilient system is forgiving of external shocks. As resilience declines the magnitude of a shock from which it cannot recover gets smaller and smaller. Resilience shifts attention from purely growth and efficiency to needed recovery and flexibility…Systems are never static, they tend to move through four, recurring phases, known as an adaptive cycle. Generally, the pattern of change is a sequence from a rapid growth phase through to a conservation phase in which resources are increasingly unavailable, locked up in existing structures, followed by a release phase that quickly moves into a phase of reorganisation, and thence into another growth phase.” – Resilience Alliance

Adaptive Control Valves versus Circuit Breakers

Adaptive control valves are dynamically added into code at runtime. It is not necessary to explicitly call into an API and introduce a compile time dependency. No command framework or actor programming model with software circuit breaker capabilities needs to be adopted pervasively (and perversely). Safety valves can be automatically introduced into any method that is metered. Valves can be specified at deployment time via externalized configuration in comparison circuit breaker APIs require hardwiring at development time.

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