Implementing Domain-Driven Design

Latency Tolerances

Won’t the potentially long latency periods before a message is received—where eventual consistency represents delays of more than a few milliseconds—cause problems? Certainly this is a matter to consider carefully, given that out-of-sync data could influence wrong and even damaging actions. We must ask how long between consistent states is acceptable, and how much delay is too great. Domain experts will likely be very much in tune with what constitutes acceptable and unacceptable delays. It may surprise developers to learn that most times, several seconds, minutes, hours, or even days between consistent states is completely tolerable. This is not to say that it is always true. But we must not assume that in any given domain, ...