I have a Stream<A> that I want to iterate over and fetch additional information about each record from another service. In the end it should become a Stream<B>.
Since I am using Jetty I can't use .block().
How do I do that using Reactor Project?
You can use flatMap:
Flux<A> fluxA = //...;
Flux<B> fluxB = sampleFlux.flatMap(elem -> fetchDataFromRemoteService(elem));
where fetchDataFromRemoteService(A a) return Publisher.
Or you can use Flux#concatMap:
Flux<A> fluxA = //...;
Flux<B> fluxB = sampleFlux.concatMap(elem -> fetchDataFromRemoteService(elem));
The difference between flatMap and concatMap will be that in the second case, all actions will follow each other.
Or:
Stream<B> streamB = Flux.fromStream(streamA)
.flatMap(this::fetchDataFromRemoteService)
.toStream();