Examples of Async Restful services

Hi,

There are certain situations where modelling services as async is better
choice. One of the reasons can be to limit load on the backend services or
databases if the requests involve heavy processing.
Restful way of creating these services is to return 202 accepted with a URL
to poll the result or status of the request.
While I have read about and seen text book examples of this approach, I
don't know of any real life good examples of this. Can someone point me to
a good example?

Thanks,
Unmesh