title: Firebase: How do I update multiple resources atomically?
body: <p>Firebase allows for a resource to be updated <a href="https://www.firebase.com/docs/transactions.html">transactionally</a>.  As I understand it, the client does this buy sending requests to the server saying "If the old value is X, make the new value Y".  If there is contention the server could reject multiple updates form the client until one is accepted.</p>
  
  <p>Now, what if I want to update multiple resources atomically?</p>
  
  <p>What happens if the first update is accepted, and then the client is disconnected prior to the second update being accepted.  Is there any way to enclose multiple updates in an atomic transaction?  If not, is there an idiomatic solution to this problem?</p>