Multicasting is a key method for reducing duplicated work in RxJava.

When you multicast an event, you send the same event to all downstream
operators/subscribers. This is useful when you're doing an expensive operation
like a network request. You don't want to repeatedly execute identical network
requests for each subscriber - you just want to execute one then multicast the
results.

There are two ways to multicast:

1. Use a ConnectableObservable (via publish() or replay()1)
2. Use a Sub

RxBinding - RxJava binding APIs for Android's UI widgets.

Implementation of pure functional concept of talking to Android View layer in a Reactive way - artem-zinnatullin/RxUi