def kill_same_name_node(caller_id, api)
      delete_api = nil
      [@publishers, @subscribers, @services].each do |list|
        list.each do |pub|
          if pub.caller_id == caller_id and pub.api != api
            puts "killing #{caller_id}"
            delete_api = pub.api
            break
          end
        end
      end
      if delete_api
        proxy = SlaveProxy.new('/master', delete_api)
        begin
          proxy.shutdown("registered new node #{delete_api}")
        rescue
        end
        # delete
        [@publishers, @subscribers, @services].each do |list|
          list.delete_if {|x| x.api == delete_api}
        end
      end
    end
def kill_same_name_node(caller_id, api)
      delete_api = nil
      [@publishers, @subscribers, @services].each do |list|
        list.each do |pub|
          if pub.caller_id == caller_id and pub.api != api
            puts "killing #{caller_id}"
            delete_api = pub.api
            break
          end
        end
      end
      if delete_api
        proxy = SlaveProxy.new('/master', delete_api)
        begin
          proxy.shutdown("registered new node #{delete_api}")
        rescue
        end
        # delete
        [@publishers, @subscribers, @services].each do |list|
          list.delete_if {|x| x.api == delete_api}
        end
      end
    end
kill old node if the same caller_id node is exits.
 @param [String] caller_id new node's caller_id
 @param [String] api new node's XMLRPC URI