we take a component of the legacy application. We first rewrite the interface. We take a piece of the legacy application as a module and rewrite it into microservices. Then we take that module that is still inside the legacy application, take out all the back-end code, and replace that with a proxy to the microservices
— Eric Rong · Have Your Cake and Eat It: VMWare IT Adoption of PKS, Las Vegas 2018 · at 32:24