anchor.diff:  	     {ipaddress, list_to_binary(emqttd_net:ntoa(Ip))}, 
   	     {session, CleanSession}] || {Tab, ClientId, _Pid, Ip, _, _, CleanSession, _ }
   	    <- emqttd_vm:get_ets_object(SessionsTab)],
  - 
  -    JsonData = list_to_binary(mochijson2:encode(Bodys) ++ <<10>>), 
  +    JsonData = 
  +    if length(Bodys) == 0 ->
  +	<<"\[\]">>;
  +    true ->
  +        list_to_binary(mochijson2:encode(Bodys) ++ <<10>>)
  +    end,
       Req:respond({200, [{"Content-Type","application/json"}], JsonData});
   
   %%-----------------------------------topic--------------------------------------
  
positive.code:     Bodys = [[{mqtt_subscriber,  Tab},
               {topic, Topic}, 
               {qos, Qos}] || {Tab, Topic, Qos, Pid} <- SubLists],
   
      JsonData = list_to_binary(mochijson2:encode(Bodys) ++ <<10>>), 
      Req:respond({200, [{"Content-Type","application/json"}], JsonData}).
  
  
negative.code: 	     {ipaddress, list_to_binary(emqttd_net:ntoa(Ip))}, 
  	     {session, CleanSession}] || {Tab, ClientId, _Pid, Ip, _, _, CleanSession, _ }
  	    <- emqttd_vm:get_ets_object(ClientsTab)],
      JsonData = 
      if length(Bodys) == 0 ->
  	<<"\[\]">>;
      true ->
          list_to_binary(mochijson2:encode(Bodys) ++ <<10>>)
      end,
      Req:respond({200, [{"Content-Type","application/json"}], JsonData});
  
  %%-----------------------------------session--------------------------------------
  