WPF MVVM - Correct way to consume a web service asynchronously -

I have implemented MVVM in my WPF application. I was wondering what is the right way to consume web services from the WPF MVVM app.

So far, I have created a dataset interface and a class that implements this interface. This will serve as a mask / proxy for web service. ViewModel receives this class reference reference parameter so that he can make a call to receive / set up data, in this case it will be a web service call. I would be happy if you could guide me with some signals and / or direct me to some online resources. I know that there are 3 different ways to remove the asynchronous code for MVVM:

• Use of coroutines:

• Using RX "Reactive Extensions" (This Newest):

We know that using all other advanced technologies except the "classical" solution.