diff --git a/apps/emqtt/include/emqtt_log.hrl b/apps/emqtt/include/emqtt_log.hrl
deleted file mode 100644
index cb9215ebc..000000000
--- a/apps/emqtt/include/emqtt_log.hrl
+++ /dev/null
@@ -1,85 +0,0 @@
-%%-----------------------------------------------------------------------------
-%% Copyright (c) 2014, Feng Lee <feng@slimchat.io>
-%% 
-%% Permission is hereby granted, free of charge, to any person obtaining a copy
-%% of this software and associated documentation files (the "Software"), to deal
-%% in the Software without restriction, including without limitation the rights
-%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-%% copies of the Software, and to permit persons to whom the Software is
-%% furnished to do so, subject to the following conditions:
-%% 
-%% The above copyright notice and this permission notice shall be included in all
-%% copies or substantial portions of the Software.
-%% 
-%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-%% SOFTWARE.
-%%------------------------------------------------------------------------------
-
-%%------------------------------------------------------------------------------
-%% Logging mechanism
-%%------------------------------------------------------------------------------
--define(PRINT(Format, Args),
-    io:format(Format, Args)).
-
--define(PRINT_MSG(Msg),
-    io:format(Msg)).
-
--define(DEBUG(Format, Args),
-    lager:debug(Format, Args)).
-
--define(DEBUG_TRACE(Dest, Format, Args),
-    lager:debug(Dest, Format, Args)).
-
--define(DEBUG_MSG(Msg),
-    lager:debug(Msg)).
-
--define(INFO(Format, Args),
-    lager:info(Format, Args)).
-
--define(INFO_TRACE(Dest, Format, Args),
-    lager:info(Dest, Format, Args)).
-
--define(INFO_MSG(Msg),
-    lager:info(Msg)).
-
--define(WARN(Format, Args),
-    lager:warning(Format, Args)).
-
--define(WARN_TRACE(Dest, Format, Args),
-    lager:warning(Dest, Format, Args)).
-
--define(WARN_MSG(Msg),
-    lager:warning(Msg)).
-			      
--define(WARNING(Format, Args),
-    lager:warning(Format, Args)).
-
--define(WARNING_TRACE(Dest, Format, Args),
-    lager:warning(Dest, Format, Args)).
-
--define(WARNING_MSG(Msg),
-    lager:warning(Msg)).
-
--define(ERROR(Format, Args),
-    lager:error(Format, Args)).
-
--define(ERROR_TRACE(Dest, Format, Args),
-    lager:error(Dest, Format, Args)).
-
--define(ERROR_MSG(Msg),
-    lager:error(Msg)).
-
--define(CRITICAL(Format, Args),
-    lager:critical(Format, Args)).
-
--define(CRITICAL_TRACE(Dest, Format, Args),
-    lager:critical(Dest, Format, Args)).
-
--define(CRITICAL_MSG(Msg),
-    lager:critical(Msg)).
-
diff --git a/apps/emqtt/src/emqtt_app.erl b/apps/emqtt/src/emqtt_app.erl
index b8fac497f..3b9aeff9d 100644
--- a/apps/emqtt/src/emqtt_app.erl
+++ b/apps/emqtt/src/emqtt_app.erl
@@ -24,13 +24,15 @@
 
 -author('feng@slimchat.io').
 
--include("emqtt_log.hrl").
-
 -behaviour(application).
 
 %% Application callbacks
 -export([start/2, stop/1]).
 
+-define(PRINT_MSG(Msg), io:format(Msg)).
+
+-define(PRINT(Format, Args), io:format(Format, Args)).
+
 %% ===================================================================
 %% Application callbacks
 %% ===================================================================
diff --git a/apps/emqtt/src/emqtt_auth.erl b/apps/emqtt/src/emqtt_auth.erl
index 0905ef8ee..ba3202e0a 100644
--- a/apps/emqtt/src/emqtt_auth.erl
+++ b/apps/emqtt/src/emqtt_auth.erl
@@ -26,8 +26,6 @@
 
 -include("emqtt.hrl").
 
--include("emqtt_log.hrl").
-
 -export([start_link/0,
 		add/2,
 		check/1, check/2,
@@ -73,7 +71,6 @@ init([]) ->
 	ok = AuthMod:init(Opts),
 	ets:new(?TAB, [named_table, protected]),
 	ets:insert(?TAB, {mod, AuthMod}),
-	?PRINT("emqtt authmod is ~p", [AuthMod]),
 	{ok, undefined}.
 
 authmod(Name) when is_atom(Name) ->
diff --git a/apps/emqtt/src/emqtt_client.erl b/apps/emqtt/src/emqtt_client.erl
index cd3132774..8ed84a55e 100644
--- a/apps/emqtt/src/emqtt_client.erl
+++ b/apps/emqtt/src/emqtt_client.erl
@@ -37,8 +37,6 @@
 
 -include("emqtt.hrl").
 
--include("emqtt_log.hrl").
-
 -include("emqtt_frame.hrl").
 
 %%Client State...
@@ -91,7 +89,7 @@ handle_info(timeout, State) ->
     
 handle_info({stop, duplicate_id}, State=#state{conn_name=ConnName}) ->
 	%%TODO:
-	%?ERROR("Shutdown for duplicate clientid:~s, conn:~s", [ClientId, ConnName]), 
+	%lager:error("Shutdown for duplicate clientid:~s, conn:~s", [ClientId, ConnName]), 
 	stop({shutdown, duplicate_id}, State);
 
 %%TODO: ok??
@@ -116,7 +114,7 @@ handle_info({inet_reply, _Sock, {error, Reason}}, State) ->
 handle_info(keep_alive_timeout, #state{keep_alive=KeepAlive}=State) ->
 	case emqtt_keep_alive:state(KeepAlive) of
 	idle ->
-		?INFO("keep_alive timeout: ~p", [State#state.conn_name]),
+		lager:info("keep_alive timeout: ~p", [State#state.conn_name]),
 		{stop, normal, State};
 	active ->
 		KeepAlive1 = emqtt_keep_alive:reset(KeepAlive),
@@ -124,7 +122,7 @@ handle_info(keep_alive_timeout, #state{keep_alive=KeepAlive}=State) ->
 	end;
 
 handle_info(Info, State) ->
-	?ERROR("badinfo :~p",[Info]),
+	lager:error("badinfo :~p",[Info]),
 	{stop, {badinfo, Info}, State}.
 
 terminate(_Reason, #state{proto_state = ProtoState}) ->
@@ -165,7 +163,7 @@ process_received_bytes(Bytes,
 			  State#state{ parse_state = emqtt_frame:initial_state(),
 						   proto_state = ProtoState1 });
 		{error, Error} ->
-			?ERROR("MQTT protocol error ~p for connection ~p~n", [Error, ConnStr]),
+			lager:error("MQTT protocol error ~p for connection ~p~n", [Error, ConnStr]),
 			stop({shutdown, Error}, State);
 		{error, Error, ProtoState1} ->
 			stop({shutdown, Error}, State#state{proto_state = ProtoState1});
@@ -173,14 +171,14 @@ process_received_bytes(Bytes,
 			stop(normal, State#state{proto_state = ProtoState1})
 		end;
 	{error, Error} ->
-		?ERROR("MQTT detected framing error ~p for connection ~p~n", [ConnStr, Error]),
+		lager:error("MQTT detected framing error ~p for connection ~p~n", [ConnStr, Error]),
 		stop({shutdown, Error}, State)
     end.
 
 %%----------------------------------------------------------------------------
 network_error(Reason,
               State = #state{ conn_name  = ConnStr}) ->
-    ?ERROR("MQTT detected network error '~p' for ~p", [Reason, ConnStr]),
+    lager:error("MQTT detected network error '~p' for ~p", [Reason, ConnStr]),
 	%%TODO: where to SEND WILL MSG??
     %%send_will_msg(State),
     % todo: flush channel after publish
diff --git a/apps/emqtt/src/emqtt_cm.erl b/apps/emqtt/src/emqtt_cm.erl
index 94e5424e0..bd5562aba 100644
--- a/apps/emqtt/src/emqtt_cm.erl
+++ b/apps/emqtt/src/emqtt_cm.erl
@@ -25,8 +25,6 @@
 
 -author('feng@slimchat.io').
 
--include("emqtt_log.hrl").
-
 -behaviour(gen_server).
 
 -define(SERVER, ?MODULE).
@@ -85,7 +83,7 @@ init(Args) ->
 handle_call({create, ClientId, Pid}, _From, State) ->
 	case ets:lookup(?TAB, ClientId) of
         [{_, Pid, _}] ->
-			?ERROR("client '~s' has been registered with ~p", [ClientId, Pid]),
+			lager:error("client '~s' has been registered with ~p", [ClientId, Pid]),
             ignore;
 		[{_, OldPid, MRef}] ->
 			OldPid ! {stop, duplicate_id},
@@ -107,7 +105,7 @@ handle_cast({destroy, ClientId, Pid}, State) when is_binary(ClientId) ->
 	[_] ->
 		ignore;
 	[] ->
-		?ERROR("cannot find client '~s' with ~p", [ClientId, Pid])
+		lager:error("cannot find client '~s' with ~p", [ClientId, Pid])
 	end,
 	{noreply, State};
 
diff --git a/apps/emqtt/src/emqtt_ctl.erl b/apps/emqtt/src/emqtt_ctl.erl
index e24587914..e5f747552 100644
--- a/apps/emqtt/src/emqtt_ctl.erl
+++ b/apps/emqtt/src/emqtt_ctl.erl
@@ -26,7 +26,11 @@
 
 -include("emqtt.hrl").
 
--include("emqtt_log.hrl").
+-define(PRINT_MSG(Msg), 
+    io:format(Msg)).
+
+-define(PRINT(Format, Args), 
+    io:format(Format, Args)).
 
 -export([status/1,
 		cluster/1,
diff --git a/apps/emqtt/src/emqtt_http.erl b/apps/emqtt/src/emqtt_http.erl
index 2458c4241..e3bdc4f90 100644
--- a/apps/emqtt/src/emqtt_http.erl
+++ b/apps/emqtt/src/emqtt_http.erl
@@ -26,8 +26,6 @@
 
 -include("emqtt.hrl").
 
--include("emqtt_log.hrl").
-
 -import(proplists, [get_value/2, get_value/3]).
 
 -export([handle/1]).
@@ -45,7 +43,7 @@ handle(Req) ->
 
 handle('POST', "/mqtt/publish", Req) ->
     Params = mochiweb_request:parse_post(Req),
-	?INFO("~p~n", [Params]),
+	lager:info("~p~n", [Params]),
 	Topic = list_to_binary(get_value("topic", Params)),
 	Message = list_to_binary(get_value("message", Params)),
 	emqtt_pubsub:publish(#mqtt_msg {
diff --git a/apps/emqtt/src/emqtt_monitor.erl b/apps/emqtt/src/emqtt_monitor.erl
index 608dc2701..996600707 100644
--- a/apps/emqtt/src/emqtt_monitor.erl
+++ b/apps/emqtt/src/emqtt_monitor.erl
@@ -24,8 +24,6 @@
 
 -author('feng@slimchat.io').
 
--include("emqtt_log.hrl").
-
 -behavior(gen_server).
 
 -export([start_link/0]).
@@ -50,7 +48,6 @@ start_link() ->
 %%--------------------------------------------------------------------
 init([]) ->
     erlang:system_monitor(self(), [{long_gc, 5000}, {large_heap, 1000000}, busy_port]),
-    ?INFO("monitor is started...[ok]", []),
     {ok, #state{}}.
 %%--------------------------------------------------------------------
 %% Function: %% handle_call(Request, From, State) -> {reply, Reply, State} |
@@ -62,7 +59,7 @@ init([]) ->
 %% Description: Handling call messages
 %%--------------------------------------------------------------------
 handle_call(Request, _From, State) ->
-    ?ERROR("unexpected request: ~p", [Request]),
+    lager:error("unexpected request: ~p", [Request]),
     {reply, {error, unexpected_request}, State}.
 %%--------------------------------------------------------------------
 %% Function: handle_cast(Msg, State) -> {noreply, State} |
@@ -71,7 +68,7 @@ handle_call(Request, _From, State) ->
 %% Description: Handling cast messages
 %%--------------------------------------------------------------------
 handle_cast(Msg, State) ->
-    ?ERROR("unexpected msg: ~p", [Msg]),
+    lager:error("unexpected msg: ~p", [Msg]),
     {noreply, State}.
 %%--------------------------------------------------------------------
 %% Function: handle_info(Info, State) -> {noreply, State} |
@@ -80,22 +77,22 @@ handle_cast(Msg, State) ->
 %% Description: Handling all non call/cast messages
 %%--------------------------------------------------------------------
 handle_info({monitor, GcPid, long_gc, Info}, State) ->
-    ?ERROR("long_gc: gcpid = ~p, ~p ~n ~p", [GcPid, process_info(GcPid, 
+    lager:error("long_gc: gcpid = ~p, ~p ~n ~p", [GcPid, process_info(GcPid, 
 		[registered_name, memory, message_queue_len,heap_size,total_heap_size]), Info]),
     {noreply, State};
 
 handle_info({monitor, GcPid, large_heap, Info}, State) ->
-    ?ERROR("large_heap: gcpid = ~p,~p ~n ~p", [GcPid, process_info(GcPid, 
+    lager:error("large_heap: gcpid = ~p,~p ~n ~p", [GcPid, process_info(GcPid, 
 		[registered_name, memory, message_queue_len,heap_size,total_heap_size]), Info]),
     {noreply, State};
 
 handle_info({monitor, SusPid, busy_port, Port}, State) ->
-    ?ERROR("busy_port: suspid = ~p, port = ~p", [process_info(SusPid, 
+    lager:error("busy_port: suspid = ~p, port = ~p", [process_info(SusPid, 
 		[registered_name, memory, message_queue_len,heap_size,total_heap_size]), Port]),
     {noreply, State};
 
 handle_info(Info, State) ->
-    ?ERROR("unexpected info: ~p", [Info]),
+    lager:error("unexpected info: ~p", [Info]),
     {noreply, State}.
 
 %%--------------------------------------------------------------------
diff --git a/apps/emqtt/src/emqtt_protocol.erl b/apps/emqtt/src/emqtt_protocol.erl
index 5438f4e64..34da96b7c 100644
--- a/apps/emqtt/src/emqtt_protocol.erl
+++ b/apps/emqtt/src/emqtt_protocol.erl
@@ -24,8 +24,6 @@
 
 -include("emqtt.hrl").
 
--include("emqtt_log.hrl").
-
 -include("emqtt_frame.hrl").
 
 -record(proto_state, {
@@ -75,7 +73,7 @@ info(#proto_state{ message_id	= MsgId,
 
 handle_frame(Frame = #mqtt_frame{ fixed = #mqtt_frame_fixed{ type = Type }}, 
 				State = #proto_state{client_id = ClientId}) ->
-	?INFO("frame from ~s: ~p", [ClientId, Frame]),
+	lager:info("frame from ~s: ~p", [ClientId, Frame]),
 	case validate_frame(Type, Frame) of	
 	ok ->
 		handle_request(Type, Frame, State);
@@ -101,10 +99,10 @@ handle_request(?CONNECT,
             _ ->
                 case emqtt_auth:check(Username, Password) of
                     false ->
-                        ?ERROR_MSG("MQTT login failed - no credentials"),
+                        lager:error_MSG("MQTT login failed - no credentials"),
                         {?CONNACK_CREDENTIALS, State};
                     true ->
-						?INFO("connect from clientid: ~p, ~p", [ClientId, AlivePeriod]),
+						lager:info("connect from clientid: ~p, ~p", [ClientId, AlivePeriod]),
 						%%TODO: 
 						%%KeepAlive = emqtt_keep_alive:new(AlivePeriod*1500, keep_alive_timeout),
 						emqtt_cm:create(ClientId, self()),
@@ -113,7 +111,7 @@ handle_request(?CONNECT,
 											 client_id  = ClientId }}
                 end
         end,
-		?INFO("recv conn...:~p", [ReturnCode]),
+		lager:info("recv conn...:~p", [ReturnCode]),
 		send_frame(Sock, #mqtt_frame{ fixed = #mqtt_frame_fixed{ type = ?CONNACK},
 								 variable = #mqtt_frame_connack{
                                          return_code = ReturnCode }}),
@@ -216,7 +214,7 @@ handle_request(?PINGREQ, #mqtt_frame{}, #proto_state{socket=Sock}=State) ->
     {ok, State};
 
 handle_request(?DISCONNECT, #mqtt_frame{}, State=#proto_state{client_id=ClientId}) ->
-	?INFO("~s disconnected", [ClientId]),
+	lager:info("~s disconnected", [ClientId]),
     {stop, State}.
 
 -spec send_message(Message, State) -> {ok, NewState} when
@@ -259,7 +257,7 @@ send_message(Message, State = #proto_state{socket = Sock, message_id = MsgId}) -
 	end.
 
 send_frame(Sock, Frame) ->
-	?INFO("send frame:~p", [Frame]),
+	lager:info("send frame:~p", [Frame]),
     erlang:port_command(Sock, emqtt_frame:serialise(Frame)).
 
 %%TODO: fix me later...
@@ -312,7 +310,7 @@ validate_frame(?UNSUBSCRIBE, #mqtt_frame{variable = #mqtt_frame_subscribe{topic_
 						not emqtt_topic:validate({subscribe, Topic})],
 	case ErrTopics of
 	[] -> ok;
-	_ -> ?ERROR("error topics: ~p", [ErrTopics]), {error, badtopic}
+	_ -> lager:error("error topics: ~p", [ErrTopics]), {error, badtopic}
 	end;
 
 validate_frame(?SUBSCRIBE, #mqtt_frame{variable = #mqtt_frame_subscribe{topic_table = Topics}}) ->
@@ -320,7 +318,7 @@ validate_frame(?SUBSCRIBE, #mqtt_frame{variable = #mqtt_frame_subscribe{topic_ta
 						not (emqtt_topic:validate({subscribe, Topic}) and (Qos < 3))],
 	case ErrTopics of
 	[] -> ok;
-	_ -> ?ERROR("error topics: ~p", [ErrTopics]), {error, badtopic}
+	_ -> lager:error("error topics: ~p", [ErrTopics]), {error, badtopic}
 	end;
 
 validate_frame(_Type, _Frame) ->
diff --git a/apps/emqtt/src/emqtt_pubsub.erl b/apps/emqtt/src/emqtt_pubsub.erl
index 22d47a90e..a9785deee 100644
--- a/apps/emqtt/src/emqtt_pubsub.erl
+++ b/apps/emqtt/src/emqtt_pubsub.erl
@@ -26,8 +26,6 @@
 
 -include("emqtt.hrl").
 
--include("emqtt_log.hrl").
-
 -include("emqtt_topic.hrl").
 
 -include_lib("stdlib/include/qlc.hrl").
@@ -174,7 +172,7 @@ handle_cast(Msg, State) ->
 handle_info({'DOWN', Mon, _Type, _Object, _Info}, State) ->
 	case get({submon, Mon}) of
 	undefined ->
-		?ERROR("unexpected 'DOWN': ~p", [Mon]);
+		lager:error("unexpected 'DOWN': ~p", [Mon]);
 	SubPid ->
 		erase({submon, Mon}),
 		erase({subscriber, SubPid}),
diff --git a/apps/emqtt/src/emqtt_retained.erl b/apps/emqtt/src/emqtt_retained.erl
index fb57d223a..69d643761 100644
--- a/apps/emqtt/src/emqtt_retained.erl
+++ b/apps/emqtt/src/emqtt_retained.erl
@@ -46,8 +46,6 @@
 
 -include("emqtt.hrl").
 
--include("emqtt_log.hrl").
-
 -export([start_link/0,
 		lookup/1,
 		insert/2,