I was thinking about the age-old issue of using TCP vs. UDP in an online roleplaying game (yes, we are all naieve overachievers here, heh), and I came up with a couple questions I haven''t really seen answered. To the best of my knowledge, Ultima Online used TCP and stream sockets for its networking code. At least, the UOX server emulator for UO I helped out with at one point did, and as far as I know you can''t mix and match TCP/UDP sockets, so UO must have used it too. So how did they manage to get 3000+ people on a server? I read somewhere each process was limited to a certain number of sockets...how would one get around this limit? I think it would be disasterous to have several instances of the server app all running simultaneously. Basically that''s my question...how was UO able to basically eliminate lag (when insane numbers of people weren''t on screen which would also choke UDP anyway), and get around the sockets-per-process limit? Maybe it has to do with dividing the load between multiple machines? I''d like to hear any insights, because UDP is a pain in the butt and I''d rather use TCP if I could get around its limits . Anthracks

Simple.

UO wasn''t "A" Server... it was a series of server''s all connected together. For example you have a map
|1|2|3|4|
|5|6|7|8|

Let''s say each "cell" represents a part of the total map.

1 server for handle each "part" of the map, so it you move from part 2, to part 3, you were really jumping from 1 server to another. Well kinda hard to explained but this was discussed in a thread here about a month ago. which several UOX helpers/programmers discussed details on how to handle such thing''s.

To put it simply there was a "master server" then lot''s of server''s to handle bits and pieces.