BookService.java

@Singleton
@Path("book")
public class BookService {

    private static final String BOOKSERVICE = "http://localhost:8080/bookservice";
    private static final String COMMENTSERVICE = "http://localhost:8080/bookcomments";

    @Resource(name = "DefaultManagedExecutorService")
    ManagedExecutorService executor;

    Client bookServiceClient;
    WebTarget bookServiceTarget;

    Client commentServiceClient;
    WebTarget commentServiceTarget;

    @PostConstruct
    void initializeRestClients() {

        bookServiceClient = ClientBuilder.newClient();
        bookServiceTarget = bookServiceClient.target(BOOKSERVICE + "/rest/bookinfo");

        commentServiceClient = ClientBuilder.newClient();
        commentServiceTarget = commentServiceClient.target(COMMENTSERVICE + "/rest/comments");

    }

    @GET
    @Path("{isbn}")
    @Produces(MediaType.APPLICATION_JSON)
    public void bookAndComment(@Suspended final AsyncResponse asyncResponse, @PathParam("isbn") String isbn) {
    //RxJava code shown below
    }
}