我如何使用可观察项而不是承诺?

我有一个带有一些方法的服务,其中大多数都需要完成某个回调才能完成任务。有了承诺,在pseudo中,很容易做到这一点:

ready = http.get(stuff); // Returns a promise, resolves after a while

methodOne() { // methods sometimes called before promise resolves
    this.ready.then(_ => { 
        // doStuff
    });
}

methodTwo() {
    return this.ready.then(d => {
        // doOtherStuff
    });
}

实际上,我只需要检查它是否准备好(什么 methodOne methodTwo ,也很容易得到更多的东西)。

承诺会记住它的价值,并知道它是否得到了解决。一个可观察的有点复杂,创建同样的流似乎很麻烦。我需要任何订阅可观察对象的东西,当它准备好时就知道。有时,该方法在可观察物发射之前调用,有时在可观察物发射之后调用。

我现在有这个,但它似乎不起作用:

this.ready$ = someObservable // Will fire after a litle while but never finish - i only need the first to check though.
  .publishReplay(1).refCount(); // Trying to replay if subscription comes after emit.

this.ready$.subscribe(_ => {
    // This will be called
});

methodOne() { 
    this.ready$.subscribe(_ => {
        // Not called
    });
};

也许我误解了 publishReplay refCount ?