title: Google Oauth "Service Account", how to refresh token?
body: <p>I am using Oauth to access Google Cloud Storage via their JSON API.</p>
  
  <p>All is fine, I authenticate and get an access token which has an expiration of 3600.</p>
  
  <p>What is the correct way to refresh this?</p>
  
  <p>It is my understanding that in other types of oAuth flows (i.e. Web Server), the initial authorization request returns a refresh token as well as an access token, and that the refresh token is used to ask for another access token when the current access token has expired.</p>
  
  <p>But is appears that there is no refresh token when doing server-to-server oAuth with a Google "Service Account"?</p>