Pattern for Observables that includes acknowledgement

Question

I\'m working on something that is recording data coming from a queue. It was easy enough to process the queue into an Observable so that I can have multiple endpoints in my cod

Answer 1

What you describe sounds like "backpressure". You can read about it in RxJS 4 documentation https://github.com/Reactive-Extensions/RxJS/blob/master/doc/gettingstarted/backpressure.md. However this is mentioning operators that don't exist in RxJS 5. For example have a look at "Controlled Observables" that should refer to what you need.

I think you could achieve the same with concatMap and an instance of Subject:

const asyncOperationEnd = new Subject();

source.concatMap(val => asyncOperationEnd
    .mapTo(void 0)
    .startWith(val)
    .take(2) // that's `val` and the `void 0` that ends this inner Observable
  )
  .filter(Boolean) // Always ignore `void 0`
  .subscribe(val => {
    // do some async operation...
    // call `asyncOperationEnd.next()` and let `concatMap` process another value
  });

Fro your description it actually seems like the "observer" you're mentioning works like Subject so it would make maybe more sense to make a custom Subject class that you could use in any Observable chain.