We have seen already how to define a service. The next natural step is to implement the service interface, and this is materialized in the hello-impl project. The HelloServiceImpl class is responsible for implementing your API interface. We saw this throughout the code snippets listed earlier. One important thing to notice is that all the methods don't actually execute the call, but rather return a method handle through the instance of ServiceCall. The reason behind this approach is to allow function composition in order to achieve a processing pipeline where authentication, authorization, logging, and exception handling can easily be added.
Let's move the focus back to the ServiceCall class. From the definition presented already, you can see it takes a request object and returns CompletionStage<Response>. This container is nothing...
