The purpose of Spring Cloud Netflix Hystrix is to add more resiliency solutions to a client application that aims to execute RESTful services from a set of microservices or from microservice instances registered in a Eureka server. The resiliency applied by Hystrix is the execution of a certain recovery method once a RESTful service failed to retrieve a response. Hystrix has a @HystrixCommand to wire these services to its respective fallbackMethod that can only be called given a certain fault tolerance level.

What is best in Hystrix is that it can listen to and recognize blocking, non-blocking, and reactive executions given only the restriction that both service method and its fallbackMethod must be of the same classification type like a reactive client service execution is wired to a Mono<T> or Flux<T> fallbackMethod type.