Building Reactive Microservices in Java

Chapter 2. Understanding Reactive Microservices and Vert.x

Microservices are not really a new thing. They arose from research conducted in the 1970s and have come into the spotlight recently because microservices are a way to move faster, to deliver value more easily, and to improve agility. However, microservices have roots in actor-based systems, service design, dynamic and autonomic systems, domain-driven design, and distributed systems. The fine-grained modular design of microservices inevitably leads developers to create distributed systems. As I’m sure you’ve noticed, distributed systems are hard. They fail, they are slow, they are bound by the CAP and FLP theorems. In other words, they are very complicated to build and maintain. That’s where reactive comes in.

30+ Years of Evolution

The actor model was introduced by C. Hewitt, P. Bishop, and R. Steiger in 1973. Autonomic computing, a term coined in 2001, refers to the self-managing characteristics (self-healing, self-optimization, etc.) of distributed computing resources.

But what is reactive? Reactive is an overloaded term these days. The Oxford dictionary defines reactive as “showing a response to a stimulus.” So, reactive software reacts and adapts its behavior based on the stimuli it receives. However, the responsiveness and adaptability promoted by this definition are programming challenges because the flow of computation isn’t controlled by the programmer but by the stimuli. In this chapter, we are going to see ...