Verticles then have to be modified so that they extend io.vertx.reactivex.core.AbstractVerticle instead of io.vertx.core.AbstractVerticle. How is this different? The former class extends the latter and exposes a io.vertx.reactivex.core.Vertx field.

Let’s take a look at the MainVerticle to get a better idea of how it works in practice:

Besides, the operation does not start when the method is called. It starts when you subscribe to the Single. When the operation completes, it emits the deployment id or signals the cause of the problem with a Throwable.