Serving data with a reactive GET method

Web controllers typically do one of two things: serve up data or serve up HTML. To grok the reactive way, let’s pick the first since it’s much simpler.

In the previous section, we saw a simple usage of Reactor’s Flux type. Flux is Reactor’s implementation of Publisher and provides a fistful of reactive operators.

We can use it in a web controller like this:

@RestController
public class ApiController {
  @GetMapping("/api/employees")
  Flux<Employee> employees() {
    return Flux.just( //
      new Employee("alice", "management"), //
      new Employee("bob", "payroll"));
  }
}

This RESTful web controller can be described as follows:

• @RestController: Spring Web’s annotation to indicate that this controller involves data, not templates...