ED uses number sequences based on a set rules for the procedural generator; each system (and probably each planet) has it's own seed and number sequence which is stored on Frontier's servers so we all get to see the same system, or the planet.. hence the loading screens; that's the ED client retrieving this systems unique number sequence, so it knows what and how to generate the system you're entering.
In order to retrieve Cmdr built content (ala bases), a "planet base" seed could be generated as the base is created (as the base is created around rules) and then assigned to that planet.
When a Cmdr then approaches that planet, the ED Client would request "Player Content" from "Planet X" and the only thing the server would return, is a number sequence. The client would then crunch these numbers and store it in memory ready to be rendered as a Cmdr base on your screen when you fly into view.
ED, procedural generation:
https://www.youtube.com/watch?v=iTBvpd3_Vqk