Is not a valid virtual path

Question

I am reading one xml file from the server. I have given path like this:

string xmlFilePath = Server.MapPath("http://rnd-johnf.atcl.com/NotifierService/Notifications.xml");

if (File.Exists(xmlFilePath))

{

}

I am getting error in the path 'http://rnd-johnf.atcl.com/NotifierService/Notifications.xml'  Is not a valid virtual path

Please help me....

Thanks in advance.....