If you adhere to a microservices architecture for your application, you'll get the benefits of loose coupling, meaning that every microservice is standalone enough to be developed and maintained by separate teams. This is a kind of asynchronous approach to business tasks, but it's not the only benefit; there are others. You can increase your capacity and performance by only scaling the microservices that take a huge load. To achieve this, your microservice has to be reactive, and it has to be self-sustaining, interacting with other microservices via message passing.

In this chapter, you will learn what a reactive microservice is, and how to use message passing to ensure the connectivity of microservices. Also, we will discuss whether reactive microservices can be asynchronous.

In this chapter, we will cover the following topics: 

• What is a reactive microservice?
• JSON-RPC
• gRPC