import { Observable } from "rxjs/Observable";
import { Subject } from "rxjs/Subject";
import "rxjs/add/observable/defer";
import "rxjs/add/observable/of";

const source = Observable.defer(() => Observable.of(
  Math.floor(Math.random() * 100)
));

function observer(name: string) {
  return {
    next: (value: number) => console.log(`observer ${name}: ${value}`),
    complete: () => console.log(`observer ${name}: complete`)
  };
}

function multicast<T>(source: Observable<T>) {
  const subject = new Subject<number>();
  source.subscribe(subject);
  return subject;
}

const m = multicast(source);
m.subscribe(observer("a"));
m.subscribe(observer("b"));