I wanted to use rxjs for the first time but am a bit stucked 'cause it doesn't behave exactly like I want it to: In my scenario I want to create an observable from a promise. But I want the promise only being called once (not on every subscription) and I want it not being called on creation time (defer the call to the first subscription).
First I tried this:
var source = Rx.Observable.fromPromise(_this.getMyPromise())
which causes a call to the getMyPromise function right on creation time. This is not satisfying because at that time I don't know if the source really will be used.
Then I tried:
var source = Rx.Observable.defer(function() { return _this.getMyPromise() })
which causes a call to the getMyPromise function each time a new subscription is being made to source. This makes way too many unnecessary calls to the web server. The Rx.Observable.create function seems to have the same issue.
So what is left or what am I missing?