modify

README.md

@@ -145,6 +145,14 @@ Client -> | Rule1 | --nomatch--> | Rule2 | --nomatch--> | Rule3 | -->
         allow | deny           allow | deny           allow | deny
 ~~~
 
+### Online/Offline Notification
+```bash
+ topic:
+     $SYS/broker/connection/clients/<clientID>
+ payload:
+	{"clientID":"client001","online":true/false,"timestamp":"2018-10-25T09:32:32Z"}
+```
+
 ## Performance
 
 * High throughput

broker/broker.go

@@ -617,14 +617,18 @@ func (b *Broker) removeClient(c *client) {
 func (b *Broker) PublishMessage(packet *packets.PublishPacket) {
 	var subs []interface{}
 	var qoss []byte
-	b.topicsMgr.Subscribers([]byte(packet.TopicName), packet.Qos, &subs, &qoss)
+	err := b.topicsMgr.Subscribers([]byte(packet.TopicName), packet.Qos, &subs, &qoss)
+	if err != nil {
+		log.Error("search sub client error,  ", zap.Error(err))
+		return
+	}
 
 	for _, sub := range subs {
 		s, ok := sub.(*subscription)
 		if ok {
 			err := s.client.WriterPacket(packet)
 			if err != nil {
-				log.Error("process message for psub error,  ", zap.Error(err))
+				log.Error("write message error,  ", zap.Error(err))
 			}
 		}
 	}
@@ -643,10 +647,10 @@ func (b *Broker) BroadcastUnSubscribe(subs map[string]*subscription) {
 }
 
 func (b *Broker) OnlineOfflineNotification(clientID string, online bool) {
-
 	packet := packets.NewControlPacket(packets.Publish).(*packets.PublishPacket)
+	packet.TopicName = "$SYS/broker/connection/clients/" + clientID
 	packet.Qos = 0
-	packet.Payload = []byte(fmt.Sprintf(`{"clientID":"%s","online":"%v","timestamp":"%s"}`, clientID, online, time.Now().Format(time.RFC3339)))
+	packet.Payload = []byte(fmt.Sprintf(`{"clientID":"%s","online":%v,"timestamp":"%s"}`, clientID, online, time.Now().UTC().Format(time.RFC3339)))
 
 	b.PublishMessage(packet)
 }

broker/client.go

@@ -88,7 +88,6 @@ func (c *client) init() {
 	c.info.remoteIP = strings.Split(c.conn.RemoteAddr().String(), ":")[0]
 	c.ctx, c.cancelFunc = context.WithCancel(context.Background())
 	c.subMap = make(map[string]*subscription)
-
 	c.topicsMgr = c.broker.topicsMgr
 }
 

lib/topics/memtopics.go

@@ -446,12 +446,12 @@ func nextTopicLevel(topic []byte) ([]byte, []byte, error) {
 
 			s = stateSWC
 
-		case '$':
+		// case '$':
-			if i == 0 {
+		// 	if i == 0 {
-				return nil, nil, fmt.Errorf("memtopics/nextTopicLevel: Cannot publish to $ topics")
+		// 		return nil, nil, fmt.Errorf("memtopics/nextTopicLevel: Cannot publish to $ topics")
-			}
+		// 	}
 
-			s = stateSYS
+		// 	s = stateSYS
 
 		default:
 			if s == stateMWC || s == stateSWC {