diff --git a/editor/editors.go b/editor/editors.go
index 83a9ac9..5945f33 100644
--- a/editor/editors.go
+++ b/editor/editors.go
@@ -44,7 +44,7 @@ func WSHandler(w http.ResponseWriter, r *http.Request) {
 	editorChan := util.WSChannel{Sid: sid, Conn: conn, Request: r, Time: time.Now()}
 
 	ret := map[string]interface{}{"output": "Editor initialized", "cmd": "init-editor"}
-	err := editorChan.Conn.WriteJSON(&ret)
+	err := editorChan.WriteJSON(&ret)
 	if nil != err {
 		return
 	}
@@ -92,7 +92,7 @@ func WSHandler(w http.ResponseWriter, r *http.Request) {
 
 		ret = map[string]interface{}{"output": string(output.Bytes()), "cmd": "autocomplete"}
 
-		if err := session.EditorWS[sid].Conn.WriteJSON(&ret); err != nil {
+		if err := session.EditorWS[sid].WriteJSON(&ret); err != nil {
 			glog.Error("Editor WS ERROR: " + err.Error())
 			return
 		}
diff --git a/notification/notifications.go b/notification/notifications.go
index d8b39e7..3c557ba 100644
--- a/notification/notifications.go
+++ b/notification/notifications.go
@@ -79,7 +79,7 @@ func event2Notification(e *event.Event) {
 		return
 	}
 
-	wsChannel.Conn.WriteJSON(notification)
+	wsChannel.WriteJSON(notification)
 
 	wsChannel.Refresh()
 }
@@ -98,7 +98,7 @@ func WSHandler(w http.ResponseWriter, r *http.Request) {
 	wsChan := util.WSChannel{Sid: sid, Conn: conn, Request: r, Time: time.Now()}
 
 	ret := map[string]interface{}{"notification": "Notification initialized", "cmd": "init-notification"}
-	err := wsChan.Conn.WriteJSON(&ret)
+	err := wsChan.WriteJSON(&ret)
 	if nil != err {
 		return
 	}
diff --git a/output/outputs.go b/output/outputs.go
index 0bde0de..4cd4b59 100644
--- a/output/outputs.go
+++ b/output/outputs.go
@@ -59,7 +59,7 @@ func WSHandler(w http.ResponseWriter, r *http.Request) {
 	wsChan := util.WSChannel{Sid: sid, Conn: conn, Request: r, Time: time.Now()}
 
 	ret := map[string]interface{}{"output": "Ouput initialized", "cmd": "init-output"}
-	err := wsChan.Conn.WriteJSON(&ret)
+	err := wsChan.WriteJSON(&ret)
 	if nil != err {
 		return
 	}
@@ -123,7 +123,7 @@ func RunHandler(w http.ResponseWriter, r *http.Request) {
 			channelRet["cmd"] = "run-done"
 			channelRet["output"] = ""
 
-			err := wsChannel.Conn.WriteJSON(&channelRet)
+			err := wsChannel.WriteJSON(&channelRet)
 			if nil != err {
 				glog.Error(err)
 				return
@@ -150,7 +150,7 @@ func RunHandler(w http.ResponseWriter, r *http.Request) {
 		if nil != wsChannel {
 			channelRet["cmd"] = "run"
 			channelRet["output"] = ""
-			err := wsChannel.Conn.WriteJSON(&channelRet)
+			err := wsChannel.WriteJSON(&channelRet)
 			if nil != err {
 				glog.Error(err)
 				return
@@ -177,7 +177,7 @@ func RunHandler(w http.ResponseWriter, r *http.Request) {
 					if nil != wsChannel {
 						channelRet["cmd"] = "run-done"
 						channelRet["output"] = buf
-						err := wsChannel.Conn.WriteJSON(&channelRet)
+						err := wsChannel.WriteJSON(&channelRet)
 						if nil != err {
 							glog.Error(err)
 							break
@@ -191,7 +191,7 @@ func RunHandler(w http.ResponseWriter, r *http.Request) {
 					if nil != wsChannel {
 						channelRet["cmd"] = "run"
 						channelRet["output"] = buf
-						err := wsChannel.Conn.WriteJSON(&channelRet)
+						err := wsChannel.WriteJSON(&channelRet)
 						if nil != err {
 							glog.Error(err)
 							break
@@ -219,7 +219,7 @@ func RunHandler(w http.ResponseWriter, r *http.Request) {
 
 					channelRet["cmd"] = "run-done"
 					channelRet["output"] = buf
-					err := wsChannel.Conn.WriteJSON(&channelRet)
+					err := wsChannel.WriteJSON(&channelRet)
 					if nil != err {
 						glog.Error(err)
 						break
@@ -235,7 +235,7 @@ func RunHandler(w http.ResponseWriter, r *http.Request) {
 
 					channelRet["cmd"] = "run"
 					channelRet["output"] = buf
-					err := wsChannel.Conn.WriteJSON(&channelRet)
+					err := wsChannel.WriteJSON(&channelRet)
 					if nil != err {
 						glog.Error(err)
 						break
@@ -336,7 +336,7 @@ func BuildHandler(w http.ResponseWriter, r *http.Request) {
 
 		wsChannel := session.OutputWS[sid]
 
-		err := wsChannel.Conn.WriteJSON(&channelRet)
+		err := wsChannel.WriteJSON(&channelRet)
 		if nil != err {
 			glog.Error(err)
 			return
@@ -439,7 +439,7 @@ func BuildHandler(w http.ResponseWriter, r *http.Request) {
 			glog.V(3).Infof("Session [%s] 's build [id=%d, dir=%s] has done", sid, runningId, curDir)
 
 			wsChannel := session.OutputWS[sid]
-			err := wsChannel.Conn.WriteJSON(&channelRet)
+			err := wsChannel.WriteJSON(&channelRet)
 			if nil != err {
 				glog.Error(err)
 			}
@@ -508,7 +508,7 @@ func GoTestHandler(w http.ResponseWriter, r *http.Request) {
 
 		wsChannel := session.OutputWS[sid]
 
-		err := wsChannel.Conn.WriteJSON(&channelRet)
+		err := wsChannel.WriteJSON(&channelRet)
 		if nil != err {
 			glog.Error(err)
 			return
@@ -553,7 +553,7 @@ func GoTestHandler(w http.ResponseWriter, r *http.Request) {
 		if nil != session.OutputWS[sid] {
 			wsChannel := session.OutputWS[sid]
 
-			err := wsChannel.Conn.WriteJSON(&channelRet)
+			err := wsChannel.WriteJSON(&channelRet)
 			if nil != err {
 				glog.Error(err)
 			}
@@ -623,7 +623,7 @@ func GoInstallHandler(w http.ResponseWriter, r *http.Request) {
 
 		wsChannel := session.OutputWS[sid]
 
-		err := wsChannel.Conn.WriteJSON(&channelRet)
+		err := wsChannel.WriteJSON(&channelRet)
 		if nil != err {
 			glog.Error(err)
 			return
@@ -712,7 +712,7 @@ func GoInstallHandler(w http.ResponseWriter, r *http.Request) {
 			glog.V(3).Infof("Session [%s] 's running [go install] [id=%d, dir=%s] has done", sid, runningId, curDir)
 
 			wsChannel := session.OutputWS[sid]
-			err := wsChannel.Conn.WriteJSON(&channelRet)
+			err := wsChannel.WriteJSON(&channelRet)
 			if nil != err {
 				glog.Error(err)
 			}
@@ -781,7 +781,7 @@ func GoGetHandler(w http.ResponseWriter, r *http.Request) {
 
 		wsChannel := session.OutputWS[sid]
 
-		err := wsChannel.Conn.WriteJSON(&channelRet)
+		err := wsChannel.WriteJSON(&channelRet)
 		if nil != err {
 			glog.Error(err)
 			return
@@ -825,7 +825,7 @@ func GoGetHandler(w http.ResponseWriter, r *http.Request) {
 		if nil != session.OutputWS[sid] {
 			wsChannel := session.OutputWS[sid]
 
-			err := wsChannel.Conn.WriteJSON(&channelRet)
+			err := wsChannel.WriteJSON(&channelRet)
 			if nil != err {
 				glog.Error(err)
 			}
diff --git a/session/sessions.go b/session/sessions.go
index a4df297..3c5d434 100644
--- a/session/sessions.go
+++ b/session/sessions.go
@@ -127,7 +127,7 @@ func WSHandler(w http.ResponseWriter, r *http.Request) {
 	wsChan := util.WSChannel{Sid: sid, Conn: conn, Request: r, Time: time.Now()}
 
 	ret := map[string]interface{}{"output": "Session initialized", "cmd": "init-session"}
-	err := wsChan.Conn.WriteJSON(&ret)
+	err := wsChan.WriteJSON(&ret)
 	if nil != err {
 		return
 	}
@@ -149,7 +149,7 @@ func WSHandler(w http.ResponseWriter, r *http.Request) {
 
 		ret = map[string]interface{}{"output": "", "cmd": "session-output"}
 
-		if err := wsChan.Conn.WriteJSON(&ret); err != nil {
+		if err := wsChan.WriteJSON(&ret); err != nil {
 			glog.Error("Session WS ERROR: " + err.Error())
 			return
 		}
diff --git a/shell/shells.go b/shell/shells.go
index 3485e48..9615c06 100644
--- a/shell/shells.go
+++ b/shell/shells.go
@@ -90,7 +90,7 @@ func WSHandler(w http.ResponseWriter, r *http.Request) {
 	wsChan := util.WSChannel{Sid: sid, Conn: conn, Request: r, Time: time.Now()}
 
 	ret := map[string]interface{}{"output": "Shell initialized", "cmd": "init-shell"}
-	err := wsChan.Conn.WriteJSON(&ret)
+	err := wsChan.WriteJSON(&ret)
 	if nil != err {
 		return
 	}
@@ -138,7 +138,7 @@ func WSHandler(w http.ResponseWriter, r *http.Request) {
 
 		ret = map[string]interface{}{"output": output, "cmd": "shell-output"}
 
-		if err := wsChan.Conn.WriteJSON(&ret); err != nil {
+		if err := wsChan.WriteJSON(&ret); err != nil {
 			glog.Error("Shell WS ERROR: " + err.Error())
 			return
 		}
diff --git a/static/js/notification.js b/static/js/notification.js
index 2b0fdc3..36de39f 100644
--- a/static/js/notification.js
+++ b/static/js/notification.js
@@ -37,6 +37,8 @@ var notification = {
                     notificationHTML = '';
             
             if (data.cmd && "init-notification" === data.cmd) {
+                console.log('[notification onmessage]' + e.data);
+                
                 return;
             }
 
diff --git a/util/websocket.go b/util/websocket.go
index a36d3c2..0781920 100644
--- a/util/websocket.go
+++ b/util/websocket.go
@@ -15,6 +15,7 @@
 package util
 
 import (
+	"errors"
 	"net/http"
 	"time"
 
@@ -29,6 +30,21 @@ type WSChannel struct {
 	Time    time.Time       // the latest use time
 }
 
+// WriteJSON writes the JSON encoding of v to the channel.
+func (c *WSChannel) WriteJSON(v interface{}) (ret error) {
+	if nil == c.Conn {
+		return errors.New("connection is nil, channel has been closed")
+	}
+
+	defer func() {
+		if r := recover(); nil != r {
+			ret = errors.New("channel has been closed")
+		}
+	}()
+
+	return c.Conn.WriteJSON(v)
+}
+
 // Close closed the channel.
 func (c *WSChannel) Close() {
 	if nil != c.Conn {