What is Meteor's real-time data layer?


I just received a link to a questionnaire from MDG and it says “How important is Meteor’s real-time data layer?”. But I don’t know what is Meteor’s real-time data layer.

Is it

  • optimistic UI (actions are done both on the client and the server and undone if the server invalidates ?)
  • reactivity (any change in data is automatically reflected in the client after rerendering ?)
  • all of the above
  • something else


I would think the ‘real-time’ data layer is pub/sub.
Once you’re subscribed to a data set, you’re connected to it in real-time.
This would be the cornerstone for reactivity.

I would say that optimistic UI is more closely aligned with method calls where code runs on both client and server allows for clients to make assumptions which can be corrected by the server.


Well, real-time is a bad name, but it’s about the livequery system. So basically Meteor listening to oplog messages to give updates on subscriptions.


We’re referring to this:

Unfortunately the word “reactivity” isn’t really descriptive enough because people use it to refer to all kinds of things including UI frameworks like React and Angular.