
xdmp:get-request-user() as xs:unsignedLong
  If this App Server is using application-level authentication, 
  returns the ID of the user in the last successful call to 
  xdmp:login
  .
  Otherwise, returns the ID of the user from the Authorization 
  header of this App Server request.
  If you want to get the ID of the current user, use the 
  xdmp:get-current-userid
  
  function.
xdmp:get-request-user() => 23987236