Can we pass XML file as a single variable to .aspx page....?

Hi, i want to make an XML-API where the XML file should call from "aspx" page. When the specific aspx calls, it should get the user's information parameters. Is it possible to pass the xml file as a singe varible...? How to link this xml to aspx page...? How to receive users login parameters into the aspx...? Please provide me wih sample code....