mqtt_bridge

mqtt_bridge provides a functionality to bridge between ROS and MQTT in bidirectional.

mqtt_bridge is not actively maintained now. Feel free to check out mqtt_client, a high-performance C++ ROS nodelet with recent development!

Principle

mqtt_bridge uses ROS message as its protocol. Messages from ROS are serialized by json (or messagepack) for MQTT, and messages from MQTT are deserialized for ROS topic. So MQTT messages should be ROS message compatible. (We use rosbridge_library.internal.message_conversion for message conversion.)

This limitation can be overcome by defining custom bridge class, though.

Demo

Prerequisites

$ sudo apt install python3-pip
$ sudo apt install ros-noetic-rosbridge-library
$ sudo apt install mosquitto mosquitto-clients

Install python modules

$ pip3 install -r requirements.txt

launch node

$ roslaunch mqtt_bridge demo.launch

Publish to /ping,

$ rostopic pub /ping std_msgs/Bool "data: true"

and see response to /pong.

$ rostopic echo /pong
data: True
---

Publish “hello” to /echo,

$ rostopic pub /echo std_msgs/String "data: 'hello'"

and see response to /back.

$ rostopic echo /back
data: hello
---

You can also see MQTT messages using mosquitto_sub

$ mosquitto_sub -t '#'

Usage

parameter file (config.yaml):

mqtt:
  client:
    protocol: 4      # MQTTv311
  connection:
    host: localhost
    port: 1883
    keepalive: 60
bridge:
  # ping pong
  - factory: mqtt_bridge.bridge:RosToMqttBridge
    msg_type: std_msgs.msg:Bool
    topic_from: /ping
    topic_to: ping
  - factory: mqtt_bridge.bridge:MqttToRosBridge
    msg_type: std_msgs.msg:Bool
    topic_from: ping
    topic_to: /pong

you can use any msg types like sensor_msgs.msg:Imu.

launch file:

File truncated at 100 lines see the full file