What do we mean by a "server layer"? Servers are defined by their ability to respond to requests on-demand and to perform tasks in the background.

Here are some examples of product features that rely on a server layer:

  1. Backup Servers automatically backup all of your data in the background.
  2. Discovery Previews of new content must be fetched on-demand from a server.
  3. Ranking Servers must score a large number of candidates in the background and serve the top results on-demand.
  4. Search Servers maintain large search indexes in the background so that they can efficiently answer queries on-demand.