diff --git a/README.md b/README.md
index 1e71a8fe..b1d8ebd0 100644
--- a/README.md
+++ b/README.md
@@ -243,7 +243,7 @@ m:subscribe("/topic",0, function(conn) print("subscribe success") end)
 -- publish a message with data = hello, QoS = 0, retain = 0
 m:publish("/topic","hello",0,0, function(conn) print("sent") end)
 
-m:close();  -- if auto-reconnect = 1, will reconnect.
+m:close();  -- if auto-reconnect == 1, will disable auto-reconnect and then disconnect from host.
 -- you can call m:connect again
 
 ```
diff --git a/app/include/user_version.h b/app/include/user_version.h
index 79d104c5..06bce33b 100644
--- a/app/include/user_version.h
+++ b/app/include/user_version.h
@@ -7,6 +7,6 @@
 #define NODE_VERSION_INTERNAL   0U
 
 #define NODE_VERSION	"NodeMCU 0.9.5"
-#define BUILD_DATE	    "build 20150331"
+#define BUILD_DATE	    "build 20150403"
 
 #endif	/* __USER_VERSION_H__ */
diff --git a/app/modules/mqtt.c b/app/modules/mqtt.c
index d64a831b..ce303af2 100644
--- a/app/modules/mqtt.c
+++ b/app/modules/mqtt.c
@@ -17,8 +17,6 @@
 #include "mqtt_msg.h"
 #include "msg_queue.h"
 
-static lua_State *gL = NULL;
-
 #define MQTT_BUF_SIZE 1024
 #define MQTT_DEFAULT_KEEPALIVE 60
 #define MQTT_MAX_CLIENT_LEN   64
@@ -50,18 +48,16 @@ typedef struct mqtt_state_t
   int auto_reconnect;
   mqtt_connect_info_t* connect_info;
   uint8_t* in_buffer;
-  uint8_t* out_buffer;
   int in_buffer_length;
-  int out_buffer_length;
   uint16_t message_length;
   uint16_t message_length_read;
-  mqtt_message_t* outbound_message;
   mqtt_connection_t mqtt_connection;
   msg_queue_t* pending_msg_q;
 } mqtt_state_t;
 
 typedef struct lmqtt_userdata
 {
+  lua_State *L;
   struct espconn *pesp_conn;
   int self_ref;
   int cb_connect_ref;
@@ -80,6 +76,8 @@ typedef struct lmqtt_userdata
 }lmqtt_userdata;
 
 static void socket_connect(struct espconn *pesp_conn);
+static void mqtt_socket_reconnected(void *arg, sint8_t err);
+static void mqtt_socket_connected(void *arg);
 
 static void mqtt_socket_disconnected(void *arg)    // tcp only
 {
@@ -94,33 +92,47 @@ static void mqtt_socket_disconnected(void *arg)    // tcp only
 
   os_timer_disarm(&mud->mqttTimer);
 
-  if(mud->pesp_conn){
-    mud->pesp_conn->reverse = NULL;
-    if(mud->pesp_conn->proto.tcp)
-      c_free(mud->pesp_conn->proto.tcp);
-    mud->pesp_conn->proto.tcp = NULL;
-    c_free(mud->pesp_conn);
-    mud->pesp_conn = NULL;
-  }
-
   if(mud->connected){     // call back only called when socket is from connection to disconnection.
     mud->connected = false;
-    if((mud->cb_disconnect_ref != LUA_NOREF) && (mud->self_ref != LUA_NOREF)) {
-      lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->cb_disconnect_ref);
-      lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata(client) to callback func in lua
+    if((mud->L != NULL) && (mud->cb_disconnect_ref != LUA_NOREF) && (mud->self_ref != LUA_NOREF)) {
+      lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->cb_disconnect_ref);
+      lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata(client) to callback func in lua
       call_back = true;
     }
   }
 
-  lua_gc(gL, LUA_GCSTOP, 0);
-  if(mud->self_ref != LUA_NOREF){   // TODO: should we unref the client and delete it?
-    luaL_unref(gL, LUA_REGISTRYINDEX, mud->self_ref);
-    mud->self_ref = LUA_NOREF; // unref this, and the mqtt.socket userdata will delete it self
-  }
-  lua_gc(gL, LUA_GCRESTART, 0);
+  if(mud->mqtt_state.auto_reconnect){
+    mud->pesp_conn->reverse = mud;
+    mud->pesp_conn->type = ESPCONN_TCP;
+    mud->pesp_conn->state = ESPCONN_NONE;
+    mud->connected = false;
+    mud->pesp_conn->proto.tcp->remote_port = mud->mqtt_state.port;
+    mud->pesp_conn->proto.tcp->local_port = espconn_port();
+    espconn_regist_connectcb(mud->pesp_conn, mqtt_socket_connected);
+    espconn_regist_reconcb(mud->pesp_conn, mqtt_socket_reconnected);
+    socket_connect(pesp_conn);
+  } else {
+    if(mud->pesp_conn){
+      mud->pesp_conn->reverse = NULL;
+      if(mud->pesp_conn->proto.tcp)
+        c_free(mud->pesp_conn->proto.tcp);
+      mud->pesp_conn->proto.tcp = NULL;
+      c_free(mud->pesp_conn);
+      mud->pesp_conn = NULL;
+    }
 
-  if(call_back){
-    lua_call(gL, 1, 0);
+    if(mud->L == NULL)
+      return;
+    lua_gc(mud->L, LUA_GCSTOP, 0);
+    if(mud->self_ref != LUA_NOREF){   // TODO: should we unref the client and delete it?
+      luaL_unref(mud->L, LUA_REGISTRYINDEX, mud->self_ref);
+      mud->self_ref = LUA_NOREF; // unref this, and the mqtt.socket userdata will delete it self
+    }
+    lua_gc(mud->L, LUA_GCRESTART, 0);
+  }
+
+  if((mud->L != NULL) && call_back){
+    lua_call(mud->L, 1, 0);
   }
 
   NODE_DBG("leave mqtt_socket_disconnected.\n");
@@ -137,11 +149,11 @@ static void mqtt_socket_reconnected(void *arg, sint8_t err)
   if(mud == NULL)
     return;
 
-  pesp_conn->proto.tcp->remote_port = mud->mqtt_state.port;
-  pesp_conn->proto.tcp->local_port = espconn_port();
-
   os_timer_disarm(&mud->mqttTimer);
-  if( (mud->event_timeout != 0) || mud->mqtt_state.auto_reconnect ){
+
+  if(mud->mqtt_state.auto_reconnect){
+    pesp_conn->proto.tcp->remote_port = mud->mqtt_state.port;
+    pesp_conn->proto.tcp->local_port = espconn_port();
     socket_connect(pesp_conn);
   } else {
     mqtt_socket_disconnected(arg);
@@ -152,6 +164,8 @@ static void mqtt_socket_reconnected(void *arg, sint8_t err)
 static void deliver_publish(lmqtt_userdata * mud, uint8_t* message, int length)
 {
   NODE_DBG("enter deliver_publish.\n");
+  if(mud == NULL)
+    return;
   const char comma[] = ",";
   mqtt_event_data_t event_data;
 
@@ -165,15 +179,17 @@ static void deliver_publish(lmqtt_userdata * mud, uint8_t* message, int length)
     return;
   if(mud->self_ref == LUA_NOREF)
     return;
-  lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->cb_message_ref);
-  lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata to callback func in lua
+  if(mud->L == NULL)
+    return;
+  lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->cb_message_ref);
+  lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata to callback func in lua
 
-  lua_pushlstring(gL, event_data.topic, event_data.topic_length);
+  lua_pushlstring(mud->L, event_data.topic, event_data.topic_length);
   if(event_data.data_length > 0){
-    lua_pushlstring(gL, event_data.data, event_data.data_length);
-    lua_call(gL, 3, 0);
+    lua_pushlstring(mud->L, event_data.data, event_data.data_length);
+    lua_call(mud->L, 3, 0);
   } else {
-    lua_call(gL, 2, 0);
+    lua_call(mud->L, 2, 0);
   }
   NODE_DBG("leave deliver_publish.\n");
 }
@@ -199,7 +215,9 @@ READPACKET:
 	  return;
 
   c_memcpy(mud->mqtt_state.in_buffer, pdata, len);
-  mud->mqtt_state.outbound_message = NULL;
+  uint8_t temp_buffer[MQTT_BUF_SIZE];
+  mqtt_msg_init(&mud->mqtt_state.mqtt_connection, temp_buffer, MQTT_BUF_SIZE);
+  mqtt_message_t *temp_msg = NULL;
   switch(mud->connState){
     case MQTT_CONNECT_SENDING:
     case MQTT_CONNECT_SENT:
@@ -214,13 +232,15 @@ READPACKET:
         mud->connState = MQTT_DATA;
         NODE_DBG("MQTT: Connected\r\n");
         if(mud->cb_connect_ref == LUA_NOREF)
-          return;
+          break;
         if(mud->self_ref == LUA_NOREF)
-          return;
-        lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->cb_connect_ref);
-        lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata(client) to callback func in lua
-        lua_call(gL, 1, 0);
-        return;
+          break;
+        if(mud->L == NULL)
+          break;
+        lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->cb_connect_ref);
+        lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata(client) to callback func in lua
+        lua_call(mud->L, 1, 0);
+        break;
       }
       break;
 
@@ -248,9 +268,11 @@ READPACKET:
               break;
             if (mud->self_ref == LUA_NOREF)
               break;
-            lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->cb_suback_ref);
-            lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->self_ref);
-            lua_call(gL, 1, 0);
+            if(mud->L == NULL)
+              break;
+            lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->cb_suback_ref);
+            lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->self_ref);
+            lua_call(mud->L, 1, 0);
           }
           break;
         case MQTT_MSG_TYPE_UNSUBACK:
@@ -261,14 +283,14 @@ READPACKET:
           break;
         case MQTT_MSG_TYPE_PUBLISH:
           if(msg_qos == 1){
-            mud->mqtt_state.outbound_message = mqtt_msg_puback(&mud->mqtt_state.mqtt_connection, msg_id);
-            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), mud->mqtt_state.outbound_message, 
-                      msg_id, MQTT_MSG_TYPE_PUBACK, 0 );
+            temp_msg = mqtt_msg_puback(&mud->mqtt_state.mqtt_connection, msg_id);
+            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), temp_msg, 
+                      msg_id, MQTT_MSG_TYPE_PUBACK, (int)mqtt_get_qos(temp_msg->data) );
           }
           else if(msg_qos == 2){
-            mud->mqtt_state.outbound_message = mqtt_msg_pubrec(&mud->mqtt_state.mqtt_connection, msg_id);
-            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), mud->mqtt_state.outbound_message, 
-                      msg_id, MQTT_MSG_TYPE_PUBREC, 0 );
+            temp_msg = mqtt_msg_pubrec(&mud->mqtt_state.mqtt_connection, msg_id);
+            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), temp_msg, 
+                      msg_id, MQTT_MSG_TYPE_PUBREC, (int)mqtt_get_qos(temp_msg->data) );
           }
           if(msg_qos == 1 || msg_qos == 2){
             NODE_DBG("MQTT: Queue response QoS: %d\r\n", msg_qos);
@@ -283,9 +305,11 @@ READPACKET:
               break;
             if(mud->self_ref == LUA_NOREF)
               break;
-            lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->cb_puback_ref);
-            lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata to callback func in lua
-            lua_call(gL, 1, 0);
+            if(mud->L == NULL)
+              break;
+            lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->cb_puback_ref);
+            lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata to callback func in lua
+            lua_call(mud->L, 1, 0);
           }
 
           break;
@@ -294,18 +318,18 @@ READPACKET:
             NODE_DBG("MQTT: Publish  with QoS = 2 Received PUBREC\r\n"); 
             // Note: actrually, should not destroy the msg until PUBCOMP is received.
             msg_destroy(msg_dequeue(&(mud->mqtt_state.pending_msg_q)));
-            mud->mqtt_state.outbound_message = mqtt_msg_pubrel(&mud->mqtt_state.mqtt_connection, msg_id);
-            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), mud->mqtt_state.outbound_message, 
-                      msg_id, MQTT_MSG_TYPE_PUBREL, 1 );
+            temp_msg = mqtt_msg_pubrel(&mud->mqtt_state.mqtt_connection, msg_id);
+            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), temp_msg, 
+                      msg_id, MQTT_MSG_TYPE_PUBREL, (int)mqtt_get_qos(temp_msg->data) );
             NODE_DBG("MQTT: Response PUBREL\r\n");
           }
           break;
         case MQTT_MSG_TYPE_PUBREL:
           if(pending_msg && pending_msg->msg_type == MQTT_MSG_TYPE_PUBREC && pending_msg->msg_id == msg_id){
             msg_destroy(msg_dequeue(&(mud->mqtt_state.pending_msg_q)));
-            mud->mqtt_state.outbound_message = mqtt_msg_pubcomp(&mud->mqtt_state.mqtt_connection, msg_id);
-            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), mud->mqtt_state.outbound_message, 
-                      msg_id, MQTT_MSG_TYPE_PUBCOMP, 0 );
+            temp_msg = mqtt_msg_pubcomp(&mud->mqtt_state.mqtt_connection, msg_id);
+            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), temp_msg, 
+                      msg_id, MQTT_MSG_TYPE_PUBCOMP, (int)mqtt_get_qos(temp_msg->data) );
             NODE_DBG("MQTT: Response PUBCOMP\r\n");
           }
           break;
@@ -317,15 +341,17 @@ READPACKET:
               break;
             if(mud->self_ref == LUA_NOREF)
               break;
-            lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->cb_puback_ref);
-            lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata to callback func in lua
-            lua_call(gL, 1, 0);
+            if(mud->L == NULL)
+              break;
+            lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->cb_puback_ref);
+            lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata to callback func in lua
+            lua_call(mud->L, 1, 0);
           }
           break;
         case MQTT_MSG_TYPE_PINGREQ:
-            mud->mqtt_state.outbound_message = mqtt_msg_pingresp(&mud->mqtt_state.mqtt_connection);
-            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), mud->mqtt_state.outbound_message, 
-                      msg_id, MQTT_MSG_TYPE_PINGRESP, 1 );
+            temp_msg = mqtt_msg_pingresp(&mud->mqtt_state.mqtt_connection);
+            node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), temp_msg, 
+                      msg_id, MQTT_MSG_TYPE_PINGRESP, (int)mqtt_get_qos(temp_msg->data) );
             NODE_DBG("MQTT: Response PINGRESP\r\n");
           break;
         case MQTT_MSG_TYPE_PINGRESP:
@@ -361,7 +387,6 @@ READPACKET:
     else
       espconn_sent( pesp_conn, node->msg.data, node->msg.length );
     mud->keep_alive_tick = 0;
-    mud->mqtt_state.outbound_message = NULL;
   }
   NODE_DBG("receive, queue size: %d\n", msg_size(&(mud->mqtt_state.pending_msg_q)));
   NODE_DBG("leave mqtt_socket_received.\n");
@@ -379,12 +404,14 @@ static void mqtt_socket_sent(void *arg)
     return;
   if(!mud->connected)
     return;
-  if(mud->connState == MQTT_CONNECT_SENDING){
-    mud->connState = MQTT_CONNECT_SENT;
-  }
-
   // call mqtt_sent()
   mud->event_timeout = 0;
+
+  if(mud->connState == MQTT_CONNECT_SENDING){
+    mud->connState = MQTT_CONNECT_SENT;
+    // MQTT_CONNECT not queued.
+    return;
+  }
   NODE_DBG("sent1, queue size: %d\n", msg_size(&(mud->mqtt_state.pending_msg_q)));
   // qos = 0, publish and forgot.
   msg_queue_t *node = msg_peek(&(mud->mqtt_state.pending_msg_q));
@@ -394,9 +421,11 @@ static void mqtt_socket_sent(void *arg)
 			return;
 		if(mud->self_ref == LUA_NOREF)
 			return;
-		lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->cb_puback_ref);
-		lua_rawgeti(gL, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata to callback func in lua
-		lua_call(gL, 1, 0);
+    if(mud->L == NULL)
+      return;
+		lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->cb_puback_ref);
+		lua_rawgeti(mud->L, LUA_REGISTRYINDEX, mud->self_ref);  // pass the userdata to callback func in lua
+		lua_call(mud->L, 1, 0);
   } else if(node && node->msg_type == MQTT_MSG_TYPE_PUBACK && node->publish_qos == 1) {
     msg_destroy(msg_dequeue(&(mud->mqtt_state.pending_msg_q)));
   } else if(node && node->msg_type == MQTT_MSG_TYPE_PUBCOMP) {
@@ -422,16 +451,18 @@ static void mqtt_socket_connected(void *arg)
   espconn_regist_sentcb(pesp_conn, mqtt_socket_sent);
   espconn_regist_disconcb(pesp_conn, mqtt_socket_disconnected);
 
+  uint8_t temp_buffer[MQTT_BUF_SIZE];
   // call mqtt_connect() to start a mqtt connect stage.
-  mqtt_msg_init(&mud->mqtt_state.mqtt_connection, mud->mqtt_state.out_buffer, mud->mqtt_state.out_buffer_length);
-  mud->mqtt_state.outbound_message = mqtt_msg_connect(&mud->mqtt_state.mqtt_connection, mud->mqtt_state.connect_info);
-  NODE_DBG("Send MQTT connection infomation, data len: %d, d[0]=%d \r\n", mud->mqtt_state.outbound_message->length,  mud->mqtt_state.outbound_message->data[0]);
+  mqtt_msg_init(&mud->mqtt_state.mqtt_connection, temp_buffer, MQTT_BUF_SIZE);
+  mqtt_message_t* temp_msg = mqtt_msg_connect(&mud->mqtt_state.mqtt_connection, mud->mqtt_state.connect_info);
+  NODE_DBG("Send MQTT connection infomation, data len: %d, d[0]=%d \r\n", temp_msg->length,  temp_msg->data[0]);
   mud->event_timeout = MQTT_SEND_TIMEOUT;
+  // not queue this message. should send right now. or should enqueue this before head.
   if(mud->secure)
-    espconn_secure_sent(pesp_conn, mud->mqtt_state.outbound_message->data, mud->mqtt_state.outbound_message->length);
+    espconn_secure_sent(pesp_conn, temp_msg->data, temp_msg->length);
   else
-    espconn_sent(pesp_conn, mud->mqtt_state.outbound_message->data, mud->mqtt_state.outbound_message->length);
-  mud->mqtt_state.outbound_message = NULL;
+    espconn_sent(pesp_conn, temp_msg->data, temp_msg->length);
+
   mud->connState = MQTT_CONNECT_SENDING;
   NODE_DBG("leave mqtt_socket_connected.\n");
   return;
@@ -444,6 +475,12 @@ void mqtt_socket_timer(void *arg)
 
   if(mud == NULL)
     return;
+  if(mud->pesp_conn == NULL){
+    NODE_DBG("mud->pesp_conn is NULL.\n");
+    os_timer_disarm(&mud->mqttTimer);
+    return;
+  }
+
   NODE_DBG("timer, queue size: %d\n", msg_size(&(mud->mqtt_state.pending_msg_q)));
   if(mud->event_timeout > 0){
     NODE_DBG("event_timeout: %d.\n", mud->event_timeout);
@@ -451,20 +488,19 @@ void mqtt_socket_timer(void *arg)
     if(mud->event_timeout > 0){
       return;
     } else {
-      NODE_DBG("event timeout. \n");    
+      NODE_DBG("event timeout. \n");
+      if(mud->connState == MQTT_DATA)
+        msg_destroy(msg_dequeue(&(mud->mqtt_state.pending_msg_q)));
       // should remove the head of the queue and re-send with DUP = 1
       // Not implemented yet.
     }
   }
 
-  if(mud->pesp_conn == NULL){
-    NODE_DBG("mud->pesp_conn is NULL.\n");
-    return;
-  }
-
   if(mud->connState == MQTT_INIT){ // socket connect time out.
     NODE_DBG("Can not connect to broker.\n");
+    // Never goes here.
   } else if(mud->connState == MQTT_CONNECT_SENDING){ // MQTT_CONNECT send time out.
+    NODE_DBG("sSend MQTT_CONNECT failed.\n");
     mud->connState = MQTT_INIT;
     if(mud->secure)
       espconn_secure_disconnect(mud->pesp_conn);
@@ -488,12 +524,17 @@ void mqtt_socket_timer(void *arg)
       mud->keep_alive_tick ++;
       if(mud->keep_alive_tick > mud->mqtt_state.connect_info->keepalive){
         mud->event_timeout = MQTT_SEND_TIMEOUT;
+        uint8_t temp_buffer[MQTT_BUF_SIZE];
+        mqtt_msg_init(&mud->mqtt_state.mqtt_connection, temp_buffer, MQTT_BUF_SIZE);
         NODE_DBG("\r\nMQTT: Send keepalive packet\r\n");
-        mud->mqtt_state.outbound_message = mqtt_msg_pingreq(&mud->mqtt_state.mqtt_connection);
+        mqtt_message_t* temp_msg = mqtt_msg_pingreq(&mud->mqtt_state.mqtt_connection);
+        msg_queue_t *node = msg_enqueue( &(mud->mqtt_state.pending_msg_q), temp_msg, 
+                            0, MQTT_MSG_TYPE_PINGREQ, (int)mqtt_get_qos(temp_msg->data) );
+        // only one message in queue, send immediately.
         if(mud->secure)
-          espconn_secure_sent(mud->pesp_conn, mud->mqtt_state.outbound_message->data, mud->mqtt_state.outbound_message->length);
+          espconn_secure_sent(mud->pesp_conn, temp_msg->data, temp_msg->length);
         else
-          espconn_sent(mud->pesp_conn, mud->mqtt_state.outbound_message->data, mud->mqtt_state.outbound_message->length);
+          espconn_sent(mud->pesp_conn, temp_msg->data, temp_msg->length);
         mud->keep_alive_tick = 0;
       }
     }
@@ -523,6 +564,7 @@ static int mqtt_socket_client( lua_State* L )
   // create a object
   mud = (lmqtt_userdata *)lua_newuserdata(L, sizeof(lmqtt_userdata));
   // pre-initialize it, in case of errors
+  mud->L = NULL;
   mud->self_ref = LUA_NOREF;
   mud->cb_connect_ref = LUA_NOREF;
   mud->cb_disconnect_ref = LUA_NOREF;
@@ -545,7 +587,7 @@ static int mqtt_socket_client( lua_State* L )
   luaL_getmetatable(L, "mqtt.socket");
   lua_setmetatable(L, -2);
 
-  gL = L;   // global L for mqtt module.
+  mud->L = L;   // L for mqtt module.
 
   if( lua_isstring(L,stack) )   // deal with the clientid string
   {
@@ -584,8 +626,7 @@ static int mqtt_socket_client( lua_State* L )
   mud->connect_info.username = (uint8_t *)c_zalloc(unl + 1);
   mud->connect_info.password = (uint8_t *)c_zalloc(pwl + 1);
   mud->mqtt_state.in_buffer = (uint8_t *)c_zalloc(MQTT_BUF_SIZE);
-  mud->mqtt_state.out_buffer = (uint8_t *)c_zalloc(MQTT_BUF_SIZE);
-  if(!mud->connect_info.client_id || !mud->connect_info.username || !mud->connect_info.password || !mud->mqtt_state.in_buffer || !mud->mqtt_state.out_buffer){
+  if(!mud->connect_info.client_id || !mud->connect_info.username || !mud->connect_info.password || !mud->mqtt_state.in_buffer){
     if(mud->connect_info.client_id) {
       c_free(mud->connect_info.client_id);
       mud->connect_info.client_id = NULL;
@@ -601,10 +642,6 @@ static int mqtt_socket_client( lua_State* L )
     if(mud->mqtt_state.in_buffer) {
       c_free(mud->mqtt_state.in_buffer);
       mud->mqtt_state.in_buffer = NULL;
-    }
-    if(mud->mqtt_state.out_buffer) {
-      c_free(mud->mqtt_state.out_buffer);
-      mud->mqtt_state.out_buffer = NULL;
     }
   	return luaL_error(L, "not enough memory");
   }
@@ -624,7 +661,6 @@ static int mqtt_socket_client( lua_State* L )
   mud->connect_info.keepalive = keepalive;
 
   mud->mqtt_state.in_buffer_length = MQTT_BUF_SIZE;
-  mud->mqtt_state.out_buffer_length = MQTT_BUF_SIZE;
   mud->mqtt_state.pending_msg_q = NULL;
   mud->mqtt_state.auto_reconnect = 1;
   mud->mqtt_state.port = 1883;
@@ -690,10 +726,6 @@ static int mqtt_delete( lua_State* L )
     c_free(mud->mqtt_state.in_buffer);
     mud->mqtt_state.in_buffer = NULL;
   }
-  if(mud->mqtt_state.out_buffer){
-    c_free(mud->mqtt_state.out_buffer);
-    mud->mqtt_state.out_buffer = NULL;
-  }
   // -------
 
   // free (unref) callback ref
@@ -717,12 +749,12 @@ static int mqtt_delete( lua_State* L )
     luaL_unref(L, LUA_REGISTRYINDEX, mud->cb_puback_ref);
     mud->cb_puback_ref = LUA_NOREF;
   }
-  lua_gc(gL, LUA_GCSTOP, 0);
+  lua_gc(L, LUA_GCSTOP, 0);
   if(LUA_NOREF!=mud->self_ref){
     luaL_unref(L, LUA_REGISTRYINDEX, mud->self_ref);
     mud->self_ref = LUA_NOREF;
   }
-  lua_gc(gL, LUA_GCRESTART, 0);
+  lua_gc(L, LUA_GCRESTART, 0);
   NODE_DBG("leave mqtt_delete.\n");
   return 0;  
 }
@@ -736,6 +768,8 @@ static void socket_connect(struct espconn *pesp_conn)
   if(mud == NULL)
     return;
 
+  mud->event_timeout = MQTT_CONNECT_TIMEOUT;
+  mud->connState = MQTT_INIT;
   if(mud->secure)
     espconn_secure_connect(pesp_conn);
   else
@@ -906,8 +940,6 @@ static int mqtt_socket_connect( lua_State* L )
   os_timer_disarm(&mud->mqttTimer);
   os_timer_setfn(&mud->mqttTimer, (os_timer_func_t *)mqtt_socket_timer, mud);
   // timer started in socket_connect()
-  mud->event_timeout = MQTT_CONNECT_TIMEOUT;
-  mud->connState = MQTT_INIT;
 
   if((ipaddr.addr == IPADDR_NONE) && (c_memcmp(domain,"255.255.255.255",16) != 0))
   {
@@ -943,6 +975,7 @@ static int mqtt_socket_close( lua_State* L )
     return 0;
 
   // call mqtt_disconnect()
+  mud->mqtt_state.auto_reconnect = 0;   // stop auto reconnect.
 
   if(mud->secure){
     if(mud->pesp_conn->proto.tcp->remote_port || mud->pesp_conn->proto.tcp->local_port)
@@ -1012,32 +1045,48 @@ static int mqtt_socket_subscribe( lua_State* L ) {
 	luaL_argcheck( L, mud, stack, "mqtt.socket expected" );
 	stack++;
 
+  if(mud==NULL){
+    NODE_DBG("userdata is nil.\n");
+    lua_pushboolean(L, 0);
+    return 1;
+  }
+
+  if(mud->pesp_conn == NULL){
+    NODE_DBG("mud->pesp_conn is NULL.\n");
+    lua_pushboolean(L, 0);
+    return 1;
+  }
+
 	if(!mud->connected){
 		luaL_error( L, "not connected" );
     lua_pushboolean(L, 0);
     return 1;
   }
 
+  uint8_t temp_buffer[MQTT_BUF_SIZE];
+  mqtt_msg_init(&mud->mqtt_state.mqtt_connection, temp_buffer, MQTT_BUF_SIZE);
+  mqtt_message_t *temp_msg = NULL;
+
 	if( lua_istable( L, stack ) ) {
 		NODE_DBG("subscribe table\n");
 		lua_pushnil( L ); /* first key */
 
-    uint8_t temp_buffer[MQTT_BUF_SIZE];
+    uint8_t temp_buf[MQTT_BUF_SIZE];
     uint32_t temp_pos = 0;
 
 		while( lua_next( L, stack ) != 0 ) {
 			topic = luaL_checkstring( L, -2 );
 			qos = luaL_checkinteger( L, -1 );
 
-			mud->mqtt_state.outbound_message = mqtt_msg_subscribe( &mud->mqtt_state.mqtt_connection, topic, qos, &msg_id );
-			NODE_DBG("topic: %s - qos: %d, length: %d\n", topic, qos, mud->mqtt_state.outbound_message->length);
+			temp_msg = mqtt_msg_subscribe( &mud->mqtt_state.mqtt_connection, topic, qos, &msg_id );
+			NODE_DBG("topic: %s - qos: %d, length: %d\n", topic, qos, temp_msg->length);
 
-      if (temp_pos + mud->mqtt_state.outbound_message->length > MQTT_BUF_SIZE){
+      if (temp_pos + temp_msg->length > MQTT_BUF_SIZE){
         lua_pop(L, 1);
         break;  // too long message for the outbuffer.
       }
-      c_memcpy( temp_buffer + temp_pos, mud->mqtt_state.outbound_message->data, mud->mqtt_state.outbound_message->length );
-      temp_pos += mud->mqtt_state.outbound_message->length;
+      c_memcpy( temp_buf + temp_pos, temp_msg->data, temp_msg->length );
+      temp_pos += temp_msg->length;
 
 			lua_pop( L, 1 );
 		}
@@ -1048,9 +1097,9 @@ static int mqtt_socket_subscribe( lua_State* L ) {
       return 1;
     }
 
-    c_memcpy( mud->mqtt_state.out_buffer, temp_buffer, temp_pos );
-		mud->mqtt_state.outbound_message->data = mud->mqtt_state.out_buffer;
-		mud->mqtt_state.outbound_message->length = temp_pos;
+    c_memcpy( temp_buffer, temp_buf, temp_pos );
+		temp_msg->data = temp_buffer;
+		temp_msg->length = temp_pos;
 		stack++;
 	} else {
 		NODE_DBG("subscribe string\n");
@@ -1062,7 +1111,7 @@ static int mqtt_socket_subscribe( lua_State* L ) {
       return 1;
     }
 		qos = luaL_checkinteger( L, stack );
-		mud->mqtt_state.outbound_message = mqtt_msg_subscribe( &mud->mqtt_state.mqtt_connection, topic, qos, &msg_id );
+		temp_msg = mqtt_msg_subscribe( &mud->mqtt_state.mqtt_connection, topic, qos, &msg_id );
 		stack++;
 	}
 
@@ -1073,8 +1122,8 @@ static int mqtt_socket_subscribe( lua_State* L ) {
     mud->cb_suback_ref = luaL_ref( L, LUA_REGISTRYINDEX );
   }
 
-  msg_queue_t *node = msg_enqueue( &(mud->mqtt_state.pending_msg_q), mud->mqtt_state.outbound_message, 
-                            msg_id, MQTT_MSG_TYPE_SUBSCRIBE, (int)mqtt_get_qos(mud->mqtt_state.outbound_message->data) );
+  msg_queue_t *node = msg_enqueue( &(mud->mqtt_state.pending_msg_q), temp_msg, 
+                            msg_id, MQTT_MSG_TYPE_SUBSCRIBE, (int)mqtt_get_qos(temp_msg->data) );
 
   NODE_DBG("topic: %s - id: %d - qos: %d, length: %d\n", topic, node->msg_id, node->publish_qos, node->msg.length);
 
@@ -1093,7 +1142,6 @@ static int mqtt_socket_subscribe( lua_State* L ) {
   } else {
     lua_pushboolean(L, 1);  // enqueued succeed.
   }
-  mud->mqtt_state.outbound_message = NULL;
   NODE_DBG("subscribe, queue size: %d\n", msg_size(&(mud->mqtt_state.pending_msg_q)));
   NODE_DBG("leave mqtt_socket_subscribe.\n");
 	return 1;
@@ -1123,7 +1171,11 @@ static int mqtt_socket_publish( lua_State* L )
     return 1;
   }
 
-  pesp_conn = mud->pesp_conn;
+  if(!mud->connected){
+    luaL_error( L, "not connected" );
+    lua_pushboolean(L, 0);
+    return 1;
+  }
 
   const char *topic = luaL_checklstring( L, stack, &l );
   stack ++;
@@ -1140,7 +1192,9 @@ static int mqtt_socket_publish( lua_State* L )
   uint8_t retain = luaL_checkinteger( L, stack);
   stack ++;
 
-  mud->mqtt_state.outbound_message = mqtt_msg_publish(&mud->mqtt_state.mqtt_connection,
+  uint8_t temp_buffer[MQTT_BUF_SIZE];
+  mqtt_msg_init(&mud->mqtt_state.mqtt_connection, temp_buffer, MQTT_BUF_SIZE);
+  mqtt_message_t *temp_msg = mqtt_msg_publish(&mud->mqtt_state.mqtt_connection,
                        topic, payload, l,
                        qos, retain,
                        &msg_id);
@@ -1152,7 +1206,7 @@ static int mqtt_socket_publish( lua_State* L )
     mud->cb_puback_ref = luaL_ref(L, LUA_REGISTRYINDEX);
   }
 
-  msg_queue_t *node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), mud->mqtt_state.outbound_message, 
+  msg_queue_t *node = msg_enqueue(&(mud->mqtt_state.pending_msg_q), temp_msg, 
                       msg_id, MQTT_MSG_TYPE_PUBLISH, (int)qos );
 
   if(node && (1==msg_size(&(mud->mqtt_state.pending_msg_q))) && mud->event_timeout == 0){
@@ -1170,7 +1224,7 @@ static int mqtt_socket_publish( lua_State* L )
   } else {
     lua_pushboolean(L, 1);  // enqueued succeed.
   }
-  mud->mqtt_state.outbound_message = NULL;
+
   NODE_DBG("publish, queue size: %d\n", msg_size(&(mud->mqtt_state.pending_msg_q)));
   NODE_DBG("leave mqtt_socket_publish.\n");
   return 1;
diff --git a/app/platform/flash_fs.h b/app/platform/flash_fs.h
index 9d9da7c7..66538b90 100644
--- a/app/platform/flash_fs.h
+++ b/app/platform/flash_fs.h
@@ -71,6 +71,9 @@
 #define fs_rename myspiffs_rename
 #define fs_size myspiffs_size
 
+#define fs_mount myspiffs_mount
+#define fs_unmount myspiffs_unmount
+
 #define FS_NAME_MAX_LENGTH SPIFFS_OBJ_NAME_LEN
 
 #endif
diff --git a/app/spiffs/spiffs.c b/app/spiffs/spiffs.c
index e96e15a0..bcb11d5c 100644
--- a/app/spiffs/spiffs.c
+++ b/app/spiffs/spiffs.c
@@ -42,7 +42,7 @@ The small 4KB sectors allow for greater flexibility in applications th
 
 ********************/
 
-void spiffs_mount() {
+void myspiffs_mount() {
   spiffs_config cfg;
   cfg.phys_addr = ( u32_t )platform_flash_get_first_free_block_address( NULL ); 
   cfg.phys_addr += 0x3000;
@@ -69,6 +69,10 @@ void spiffs_mount() {
   NODE_DBG("mount res: %i\n", res);
 }
 
+void myspiffs_unmount() {
+  SPIFFS_unmount(&fs);
+}
+
 // FS formatting function
 // Returns 1 if OK, 0 for error
 int myspiffs_format( void )
@@ -85,7 +89,7 @@ int myspiffs_format( void )
   while( sect_first <= sect_last )
     if( platform_flash_erase_sector( sect_first ++ ) == PLATFORM_ERR )
       return 0;
-  spiffs_mount();
+  myspiffs_mount();
   return 1;
 }
 
diff --git a/app/spiffs/spiffs.h b/app/spiffs/spiffs.h
index c5a2c1d2..7132b92d 100644
--- a/app/spiffs/spiffs.h
+++ b/app/spiffs/spiffs.h
@@ -477,6 +477,8 @@ u32_t SPIFFS_buffer_bytes_for_cache(spiffs *fs, u32_t num_pages);
 #if SPIFFS_CACHE
 #endif
 
+void myspiffs_mount();
+void myspiffs_unmount();
 int myspiffs_open(const char *name, int flags);
 int myspiffs_close( int fd );
 size_t myspiffs_write( int fd, const void* ptr, size_t len );
diff --git a/app/user/Makefile b/app/user/Makefile
index 0dd1afe6..80c303ee 100644
--- a/app/user/Makefile
+++ b/app/user/Makefile
@@ -44,6 +44,7 @@ INCLUDES += -I ../libc
 INCLUDES += -I ../platform
 INCLUDES += -I ../lua
 INCLUDES += -I ../wofs
+INCLUDES += -I ../spiffs
 PDIR := ../$(PDIR)
 sinclude $(PDIR)Makefile
 
diff --git a/app/user/user_main.c b/app/user/user_main.c
index dee11754..88938da8 100644
--- a/app/user/user_main.c
+++ b/app/user/user_main.c
@@ -14,8 +14,7 @@
 #include "c_stdlib.h"
 #include "c_stdio.h"
 
-#include "romfs.h"
- 
+#include "flash_fs.h"
 #include "user_interface.h"
 
 #include "ets_sys.h"
@@ -44,7 +43,6 @@ void task_init(void){
     system_os_task(task_lua, USER_TASK_PRIO_0, taskQueue, TASK_QUEUE_LEN);
 }
 
-extern void spiffs_mount();
 // extern void test_spiffs();
 // extern int test_romfs();
 
@@ -69,7 +67,16 @@ void nodemcu_init(void)
         // Flash init data at FLASHSIZE - 0x04000 Byte.
         flash_init_data_default();
         // Flash blank data at FLASHSIZE - 0x02000 Byte.
-        flash_init_data_blank();        
+        flash_init_data_blank();
+        if( !fs_format() )
+        {
+            NODE_ERR( "\ni*** ERROR ***: unable to format. FS might be compromised.\n" );
+            NODE_ERR( "It is advised to re-flash the NodeMCU image.\n" );
+        }
+        else{
+            NODE_ERR( "format done.\n" );
+        }
+        fs_unmount();   // mounted by format.
     }
 #endif // defined(FLASH_SAFE_API)
 
@@ -94,7 +101,7 @@ void nodemcu_init(void)
 
     // test_romfs();
 #elif defined ( BUILD_SPIFFS )
-    spiffs_mount();
+    fs_mount();
     // test_spiffs();
 #endif
     // endpoint_setup();
diff --git a/examples/fragment.lua b/examples/fragment.lua
index 2e2e752a..9206be8c 100644
--- a/examples/fragment.lua
+++ b/examples/fragment.lua
@@ -460,3 +460,15 @@ m:publish("/topic1","hello3",0,0) m:publish("/topic1","hello2",2,0)
 
 m:subscribe("/topic2",2,function(m) print("sub done") end)
 m:publish("/topic2","hello3",0,0) m:publish("/topic2","hello2",2,0)
+
+m=mqtt.Client()
+m:on("connect",function(m) 
+	print("connection "..node.heap()) 
+	m:subscribe("/topic1",0,function(m) print("sub done") end)
+	m:publish("/topic1","hello3",0,0) m:publish("/topic1","hello2",2,0)
+	end )
+m:on("offline", function(conn)
+    print("disconnect to broker...")
+    print(node.heap())
+end)
+m:connect("192.168.18.88",1883,0,1)