Chapter 5
Stability Patterns

We have traveled through the vale of shadows. Now it is time to come in to the light. In the last chapter, we saw the antipatterns to avoid. In this chapter, we’ll look at the flip side and examine some patterns that are the inverse of the killers from the last chapter. These healthy patterns provide the architecture and design guidance to reduce, eliminate, or mitigate the effects of cracks in the system. Not one of these will help your software pass QA, but they will help you get a full night’s sleep, or at least an uninterrupted dinner with your family, once your software launches.

Don’t make the mistake of assuming that a system that includes more of these patterns is superior to one with fewer of them. “Count of patterns applied” is never a good quality metric. Instead, I want you to develop a recovery-oriented mind-set. At the risk of sounding like a broken record, I’ll say it again: expect failures. Apply these patterns wisely to reduce the damage done by an individual failure.