system.reactive - Reactive Streams Design Patterns -

i'm looking forward using reactive streams in 1 of projects. understand basics of using observable , observer! know if there design patterns should consider. example., there patterns employ when comes error handling?

when stream connected client rest endpoint, upstream system not yet ready respond requests , if have observable calls rest end-point every 2 seconds, how handle these empty responses rest calls?

i'm looking practices when using reactive streams! suggestions?