webservice - get client ip address

Hi
I have the following problem in my application I have
in the controller:

class XmlrpcController < ApplicationController
    web_service_dispatching_mode :layered
    wsdl_service_name 'weblogUpdates.ping'
    web_service_scaffold :invoke
    web_service :weblogUpdates, WeblogUpdates.new
end

in the api definition file: