As I mentioned in my previous article, “Microservice architecture is agile software architecture,” my initial reaction to microservice architecture was to question how it differed from service-oriented architecture (SOA). I was not alone in associating these two architectural styles. In their definitive blog post, James Lewis and Martin Fowler included a sidebar that contrasts microservices and SOA. In response, skeptics claimed there were no differences. And in fact, influential microservice adopters Amazon and Netflix both referred to their architectures as service-oriented before the term “microservices” was coined. More than two years later, the debate over whether microservice architecture is or is not SOA has produced a substantial library of articles.