I am using a polling method to fetch data periodically. New data may arrive at any time. I want to expose a reactive interface to my client. So, I want to create a publisher (Flux?) that would publish new data when it becomes available and notify the subscriber(s). How do I do that? All the examples of Flux that I see are for the cases where the data is already known/available. Effectively, I want something like a Flux based on a queue and my polling thread can keep filling the queue when it finds new data.
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1Okay, it looks like I need to use a sink. So, maybe Flux#create(sink) or Flux#push(sink).– PratikCommented Jun 25, 2019 at 0:31
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1 Answer
For something simple, you might want to use a DirectProcessor. This isn't the most complex of flux sinks, but it'll get you a bit of the way there.
I wrote a quick example:
Flux<String> hot = DirectProcessor.create<String>()
hot.onNext("Hello")//not printed
hot.subscribe(it -> System.out.println(it))
hot.onNext("Goodbye")//printed
Thread.sleep(100)
hot.onNext("foo")//printed
DirectProcessor implements Flux, so you can use it like a Flux.
As you can see, elements added before subscribing to the hotsource won't be passed down to the subscribe.
Looking at other posts, Flux#create and Flux#generate might be good places to start. Difference Between Flux.create and Flux.generate <- this will get you more complexity and control over the flux.
