What do you mean "they can only assign ... without port number and context root"?
Do you mean the DNS registrar and/or your ISP?
If so, all they will do is map a hostname to an IP address so
http://hostname:8000/SART will "just work", although if the ISP blocks ports you will have to use a port they allow through.
Or perhaps I just understand what you're asking.
[Message sent by forum member 'matterbury' (matterbury)]
http://forums.java.net/jive/thread.jspa?messageID=354924