Services.java

///usr/bin/env jbang "$0" "$@" ; exit $?
//DEPS io.vertx:vertx-rx-java3:4.2.5
//DEPS io.vertx:vertx-web-client:4.2.5

import io.reactivex.rxjava3.core.Single;
import io.vertx.rxjava3.core.Vertx;
import io.vertx.rxjava3.ext.web.client.HttpResponse;
import io.vertx.rxjava3.ext.web.client.WebClient;

import java.util.AbstractMap;
import java.util.concurrent.CountDownLatch;

import static java.lang.String.format;
import static java.lang.System.out;

public class Services {

    public static void main(String... args) throws InterruptedException {
        CountDownLatch countDownLatch = new CountDownLatch(1);

        // Vertx instance and web client
        Vertx vertx = Vertx.vertx();
        WebClient webClient = WebClient.create(vertx);

        // single sources. Lazy evaluation, no invocation at this point
        Single<Integer> service1Code = service1(webClient);
        Single<Integer> service2Code = service2(webClient);

        // combine results together and create tuple
        Single<AbstractMap.SimpleEntry<Integer, Integer>> tupleSource =
                    service1Code.zipWith(service2Code, (s1, s2) -> new AbstractMap.SimpleEntry<>(s1, s2));

        // subscribe and invoke services
        tupleSource
                .doFinally(countDownLatch::countDown)
                .subscribe(Services::printResult);

        vertx.setPeriodic(1000, l -> out.println("[" + Thread.currentThread().getName() + "] is released"));

        countDownLatch.await();
        vertx.rxClose().subscribe();
    }

    private static Single<Integer> service1(WebClient webClient) {
        return webClient.getAbs("http://httpstat.us/200?sleep=5000")
                .rxSend()
                .doOnSuccess(response -> out.println("[" + Thread.currentThread().getName() + "] service 1: response received"))
                .map(HttpResponse::statusCode);
    }

    private static Single<Integer> service2(WebClient webClient) {
        return webClient.getAbs("http://httpstat.us/200?sleep=2000")
                .rxSend()
                .doOnSuccess(response -> out.println("[" + Thread.currentThread().getName() + "] service 2 response received"))
                .map(HttpResponse::statusCode);
    }

    private static void printResult(AbstractMap.SimpleEntry<Integer, Integer> tuple){
        out.println(format(
                "[%s] Result: service1:%d service2:%d",
                Thread.currentThread().getName(),
                tuple.getKey(),
                tuple.getValue()
        ));
    }
}