How to access a XML file from another machine

Lets say I have two Ubuntu machine (in the real world they are two ec2 instances) U1 and U2 with ip address of 10.0.0.0 and 11.0.0.0. There is a XML file in U2 that I want to modify from a ruby file that is located in U1 when a new information arrive. I am developing in Ruby and I know about NokoGiri and how to modify the XML I just dont know how to access the U2 from my ruby file.