Cold versus hot observables

There are subtle differences in behavior depending on how Observable is implemented. A major characteristic to be aware of is a cold versus a hot Observable, which defines how an Observable behaves when it has multiple observers. First, we will cover a cold Observable.

A cold Observable

A cold Observable is much like a music CD that is provided to each listener, so each person can hear all the tracks any time they start listening to it. In the same manner, a cold Observable replays the emissions to each Observer, ensuring that it gets all the data. Most data-driven observables are cold, and this includes the observables produced by the Observable.just() and Observable.fromIterable() factories.

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