diff --git a/apps/emqtt/include/emqtt.hrl b/apps/emqtt/include/emqtt.hrl
index c73fc8f71..ff67fafde 100644
--- a/apps/emqtt/include/emqtt.hrl
+++ b/apps/emqtt/include/emqtt.hrl
@@ -45,8 +45,8 @@
 %% MQTT Client
 %%------------------------------------------------------------------------------
 -record(mqtt_client, {
-	client_id,
-	username
+    client_id,
+    username
 }).
 
 -type mqtt_client() :: #mqtt_client{}.
@@ -68,12 +68,12 @@
 %% MQTT Message
 %%------------------------------------------------------------------------------
 -record(mqtt_message, {
-    msgid				:: integer() | undefined,
-    qos		= ?QOS_0	:: mqtt_qos(),
-    retain	= false		:: boolean(),
-    dup		= false		:: boolean(),
-    topic				:: binary(),
-    payload				:: binary()
+    msgid           :: integer() | undefined,
+    qos    = ?QOS_0 :: mqtt_qos(),
+    retain = false  :: boolean(),
+    dup    = false  :: boolean(),
+    topic           :: binary(),
+    payload         :: binary()
 }).
 
 -type mqtt_message() :: #mqtt_message{}.
@@ -82,8 +82,8 @@
 %% MQTT User Management
 %%------------------------------------------------------------------------------
 -record(mqtt_user, {
-	username	:: binary(), 
-	passwdhash	:: binary()
+    username    :: binary(), 
+    passwdhash    :: binary()
 }).
 
 %%------------------------------------------------------------------------------
diff --git a/apps/emqtt/src/emqtt_retained.erl b/apps/emqtt/src/emqtt_retained.erl
index 96c605537..f7edd79f1 100644
--- a/apps/emqtt/src/emqtt_retained.erl
+++ b/apps/emqtt/src/emqtt_retained.erl
@@ -47,6 +47,7 @@
 -include("emqtt.hrl").
 
 -export([start_link/0,
+        retain/1,
 		lookup/1,
 		insert/2,
 		delete/1,
@@ -66,6 +67,11 @@
 start_link() ->
 	gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
 
+retain(Msg = #mqtt_message{retain = true}) ->
+	Msg;
+
+retain(Msg) -> Msg.
+
 lookup(Topic) ->
 	ets:lookup(retained_msg, Topic).
 
diff --git a/apps/emqtt/src/emqtt_router.erl b/apps/emqtt/src/emqtt_router.erl
index be4fbfc06..09eeaf0ce 100644
--- a/apps/emqtt/src/emqtt_router.erl
+++ b/apps/emqtt/src/emqtt_router.erl
@@ -65,7 +65,10 @@ start_link() ->
     gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
 
 route(Message) ->
-	emqtt_pubsub:publish(retained(reset_dup(Message))).
+    %%TODO: hooks later.
+	emqtt_pubsub:publish(
+        emqtt_message:unset_flag(
+            emqtt_retained:retain(Message))).
 
 %% ------------------------------------------------------------------
 %% gen_server Function Definitions
@@ -92,11 +95,4 @@ code_change(_OldVsn, State, _Extra) ->
 %% ------------------------------------------------------------------
 %% Internal Function Definitions
 %% ------------------------------------------------------------------
-retained(Msg = #mqtt_message{retain = true, topic = Topic}) ->
-	emqtt_retained:insert(Topic, Msg), Msg;
-
-retained(Msg) -> Msg.
-
-reset_dup(Msg = #mqtt_message{dup = true}) -> Msg#mqtt_message{dup = false};
-reset_dup(Msg) -> Msg.
 
diff --git a/apps/emqtt/src/emqtt_session.erl b/apps/emqtt/src/emqtt_session.erl
index e4d1e04c7..430f82ae9 100644
--- a/apps/emqtt/src/emqtt_session.erl
+++ b/apps/emqtt/src/emqtt_session.erl
@@ -235,17 +235,24 @@ handle_cast({resume, ClientId, ClientPid}, State = #session_state {
                                                 awaiting_comp = AwaitingComp,
                                                 expire_timer = ETimer}) ->
     lager:info("Session ~s resumed by ~p", [ClientId, ClientPid]),
+    %cancel timeout timer
     erlang:cancel_timer(ETimer),
 
     %% redelivery PUBREL
-    [ ClientPid ! {redeliver, {?PUBREL, PacketId}} || PacketId <- maps:keys(AwaitingComp) ],
+    lists:foreach(fun(PacketId) ->
+                ClientPid ! {redeliver, {?PUBREL, PacketId}}
+        end, maps:keys(AwaitingComp)),
 
     %% redelivery messages that awaiting PUBACK or PUBREC
     Dup = fun(Msg) -> Msg#mqtt_message{ dup = true } end,
-    [ ClientPid ! {dispatch, {self(), Dup(Message)}} || Message <- maps:values(AwaitingAck) ],
+    lists:foreach(fun(Msg) ->
+                ClientPid ! {dispatch, {self(), Dup(Msg)}}
+        end, maps:values(AwaitingAck)),
 
     %% send offline messages
-    [ClientPid ! {dispatch, {self(), Message}} || Message <- emqtt_queue:all(Queue)],
+    lists:foreach(fun(Msg) ->
+                ClientPid ! {dispatch, {self(), Msg}}
+        end, emqtt_queue:all(Queue)),
 
     NewState = State#session_state{ client_pid = ClientPid, 
                                     msg_queue = emqtt_queue:clear(Queue),