I realize this is a basic question, but how does synchronization between the client and server work with Angular? I understand the concept of data-binding once you've retrieved the data to a data-structure on the client-side, thus causing that data to update the view in the DOM, but what triggers a client-side update when your server-side data changes? Do you need to poll a REST service to check for changes? Does the server push the change to the client side? Say there's no client-action triggering an update? What causes the new server-data to get pushed to the client?