What is Replay?
We have been using RX for some time now although we still get caught out on the intricate details. Replay is an extremely useful caching mechanism that allows streams to replay previous entries for new subscriptions, based on count, time or a mixture of both.
Under the covers it’s a multicast with a replay subject:
Observable.Multicast<TSource, TSource>(source, new ReplaySubject(bufferSize))