The IObservable interface, the opposite of the IObserver interface, has the task of handling message production and the observer subscription. It routes right messages to the OnNext message handler and errors to the OnError message handler. As its life cycle ends, it acknowledges all the observers on the OnComplete message handler.
To create a valid reactive observable interface, we must write something that is not locking against user input or any other external system input data. The observable object acts as an infinite message generator, something like an infinite enumerable of messages; although in such cases, there is no enumeration.
Once a new message is available somehow, observer routes it to all the subscribers.
In the following example, we will try creating a console application to ask the user for an integer number and then route such a number to all the subscribers. Otherwise, if the given input is not a number, an error will be routed to all the subscribers...