Ok, now I'm puzzled......like that's something new

Apparently there are ways to make server side maps. Think about it, you don't have to download anything to play CTF and there are objectives in it with beef, sausage, flak guns files....etc.
How are they in there that you don't need a download?
Also, has anyone played on the BuR-Jessie and girls UK server? That server is loaded with custom maps. Omaha at night with a tank, axis objective....parachutes. The Bridge with some sort of cover over the north side of the river......allie objective. Hmmm, makes these TOW in a way. On another BuR server, the maps had rain, lightning (yes, you could be killed if struck)and depending on how many frags you played, the days became night.
So there must be some way of scripting these things that client-side computers automatically load it. Desert Eagle.......where are you. I would be very interested to learn how to make these so nobody has to download a custom map for something different.