# eMQTT Desgin Guide ## KeepAlive ## Retained ## QOS1 ## QOS2 ## Durable Subscriptions Durable Sub: Client->Queue->Router->Queue->Client Normal Sub: Client->Router->Client Router to register queues ## Topic Tree ## Offline Message ## ACL ## Authentication with clientId ## SSL/TLS Socket ## $SYS/topics and Broker statistics... ## Cluster ## Bridge