一些使用案例

轻易实现让服务器retry客户端发起的HTTP调用：

return this.http.get('/api/v1/tasks.json').retry(5).map( res => res.json());...

每隔10秒钟，轮询一次

pollTasks() {return Observable.interval(10000).flatMapLatest(() => http.get('/api/v1/tasks.json')).map(res => res.json())}// caller can do subscription and store it as a handle:let tasksSubscription =pollTasks().subscribe( data => this.payload = data);// turn it off at a later timetasksSubscription.unsubscribe();

the pollTasks() method emits a call every 10 seconds, which triggers the call inside of flatMapLatest – we’re basically ignoring the result of that event, and using it to trigger the http.get method to fetch our data. We’ll map it into JSON each time.

pollTasks方法返回一个Observable对象，封装了一个10秒间隔的周期性调用，调用内部会执行http操作读取tasks.json文件，将结果以json格式返回。

The caller of our pollTasks() method just gets an observable, which is emitting content every 10 seconds.

调用pollTasks方法，只会返回一个Observable对象，这个Observable对象subscribe之后，会每隔10秒产生内容。调用unsubscribe关闭。

Also the flatMapLatest call is really interesting – any calls generated by previous events are canceled, including their in-flight HTTP method calls. Try doing that with a promise!

flagMapLatest是一个强力方法，这里将其当作一种engine使用：所有基于之前发生的事件触发的调用都会自动被cancel，包括正在进行中的in-flight HTTP调用。很难想象使用promise实现类似的方法，会花费多大的工作量。

参考文献

总结

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