I was thinking that $SYSTEM.INetInfo.LocalHostName()
might be of help... however, that just gives the local host name, in my case "J2EDDEMOEL".
So, I tried the result of $SYSTEM.INetInfo.HostNameToAddr($SYSTEM.INetInfo.LocalHostName())
but that gives me an address that is valid only within my local area network (in my case 192.168.56.1), whereas one would need 188.8.131.52 to get to my systems from outside of the local area.
In other words: if you're only accessing that application from your local area network, the above reference would give you a usable address for the web-reference, but otherwise, I'm not sure how you'd get that programmatically.