The journey we’ve made through the architecture of distributed systems has progressed from the basic principles of communication to the intricate details of internal service design using Domain-Driven Design (DDD) and Hexagonal Architecture, and finally, how to connect everything to make asynchronous reactive systems. This chapter now guides you through the transformation of the original restaurant system from Chapter 4, “Working System,” into a resilient Reactive System, as defined by the principles of the Reactive Manifesto.