0.0.0.0 stands for all hosts on the server. Listen at this host will accept localhost, gpzhang-desktop ...
3 types of invoke:
1) remote mashalling
2) local mashalling -- no network transfer .. LocalConnection.invokeLocal
3) directly call skeleton



"system-role" is run as server itself. It does not have many priviledges ad admin@system
"admin-role" is run as admin user of the server.