Feng Lee edited this page Aug 15, 2015 · 8 revisions


One or more emqttd brokers could be bridged together. Bridge forward PUBLISH message from one broker node to another.

Clustered nodes will share/copy the same topics tree, but bridge nodes will not.


Pub -----> Broker1 --- Bridge Forward--> Broker2 -- Bridge Forward --> Broker3 -> Sub

User Guide

For example, two brokers:

Name Node MQTT Port
emqttd1 emqttd1@ 1883
emqttd2 emqttd2@ 2883

Create a bridge from emqttd1 to emqttd2, follow steps:

1. Start brokers

cd emqttd1/ && ./bin/emqttd start
cd emqttd2/ && ./bin/emqttd start

2. Create bridge on emqttd1

cd emqttd1/ && ./bin/emqttd_ctl bridges start emqttd2@ topic/# qos=2,prefix=abc/,suffix=/xyz

Print if successfully:

bridge is started."

Show bridges:

./bin/emqttd_ctl bridges list

3. Subscribe on emqttd2

mosquitto_sub -p 2883 -t topic/# -q 2 -d

4. Publish on emqttd1

mosquitto_pub -p 1883 -t topic/1 -m hello -q 1

Admin Commands

#query bridges
./bin/emqttd_ctl bridges list

#start bridge                       
./bin/emqttd_ctl bridges start <Node> <Topic>

#start bridge with options
./bin/emqttd_ctl bridges start <Node> <Topic> <Options>

#stop bridge  
./bin/emqttd_ctl bridges stop <Node> <Topic>


  qos     = 0 | 1 | 2
  prefix  = string
  suffix  = string
  queue   = integer


emqttd_bridge_sup:start_bridge(Node, SubTopic)

emqttd_bridge_sup:start_bridge(Node, SubTopic, Options)


-type option()  :: {max_queue_len, pos_integer()} |
                   {qos, mqtt_qos()} |
                   {topic_suffix, binary()} |
                   {topic_prefix, binary()} |
                   {ping_down_interval, pos_integer()}.
Option Type Description
max_queue_len pos_integer() max cache queue length(TODO: still not work)
qos mqtt_qos() reset qos
topic_suffix binary() topic suffix when forwarding message
topic_prefix binary() topic prefix when forwarding message
ping_down_interval pos_integer() ping interval when bridge node down
  1. cache messages when bridged node down?
  2. shutdown bridge when remote down?
  3. auto reconnect with remote node?
  4. RemoteTopicPrefix???

TODO: Round Robbin Bridge??

--->Bridge Group --> Bridge -> --> Bridge -> --> Bridge -> --> Bridge -> .......

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