Let's assume I have a main chain with some processing and I want to call billing service on each item processed and then return the results of the processing further like so:
... ... ... // chain starts somewhere here
.flatMap(item -> processItem(item))
.doOnNext(item -> billingService.bill(item))
... ... ... // continue to work with processed items
i.e I want to do some side effect action on the chain. This would work if billingService.bill() were sync, but it returns Mono.
So, here's what I have to do instead:
... ... ... // chain starts somewhere here
.flatMap(item -> processItem(item))
.flatMap(item -> billingService.bill(item).thenReturn(item))
... ... ... // continue to work with processed items
Is there a better way to do it? Seems kinda awkward to me...
This fire and forget pattern answers my question. So in my case it will look like this:
... ... ... // chain starts somewhere here
.flatMap(item -> processItem(item))
.doOnNext(item -> billingService.bill(item).subscribe())
... ... ... // continue to work with processed items