TransJam server runs on same computer as the web page. Applets can only
open a socket on that host computer because of browser security.
Server listens for new clients logging in, and for messages from current
clients.
Server provides a "lobby" for each application, for example, WebDrum, TicTacToe.
Each lobby contains several rooms. Rooms can be nested.
Each room tree has a maximum number of users.
Rooms contain "things" which are shared editable data objects. Kept in
RAM.
When last user in a room logs out, the room data is deleted. Not designed
for world building.