Advanced

EMQ 2.0 release supports Local Subscription and Shared Subscription.

Local Subscription

The EMQ broker will not create global routes for Local Subscription, and only dispatch MQTT messages on local node.

mosquitto_sub -t '$local/topic'

mosquitto_pub -t 'topic'

Usage: subscribe a topic with $local/ prefix.

Shared Subscription

Shared Subscription supports Load balancing to distribute MQTT messages between multiple subscribers in the same group:

                            ---------
                            |       | --Msg1--> Subscriber1
Publisher--Msg1,Msg2,Msg3-->|  EMQ  | --Msg2--> Subscriber2
                            |       | --Msg3--> Subscriber3
                            ---------

Two ways to create a shared subscription:

Prefix	Examples
$queue/	mosquitto_sub -t ‘$queue/topic’
$share/<group>/	mosquitto_sub -t ‘$share/group/topic’