EMQ X nodes can be bridged by other types of MQTT broker to achieve cross-platform message subscription and post. In this article, we present a configuration example to illustrate how to configure the bridge from Mosquitto to EMQ X.
Mosquitto is a small, lightweight, open source MQTT Broker written in C/C++ language. Mosquitto uses a single core and single thread architecture to support embedded devices deployed in limited resources, access a small number of MQTT device terminals, and implement MQTT 5.0 and 3.1.1 protocols.
Both EMQ X and Mosquitto fully support the MQTT protocol feature, but EMQ X supports more communication protocols and private protocol access. In terms of functional extension of the application, Mosquitto lacks the out-of-the-box business-related functions, such as certification authentication, rules engine, data persistence and high-performance message bridging (EMQ X enterprise editions). In the aspect of monitoring operation, maintenance and visualization management, EMQX has full existing features and extended solution support. In terms of the basic function, Mosquitto clustering is weak, and neither official nor third-party clustering solutions can support the performance requirements of large-scale massive connectivity of IoT.
Therefore, Mosquitto is not suitable for the MQTT broker for large-scale services. However, since it is lightweight and compact, it can run on any low-power microcontroller including embedded sensors, mobile devices, embedded microprocessors, and message access at the edge of the Internet of Things. It is a better technology choice for edge message access in the IoT, and the message can be processed locally and passed to the cloud by combining bridging function
Assuming we have an EMQ X server'emqx1'and a Mosquitto server, we need to create a bridge on Mosquitto to forward all ''sensor" topic messages to the'emqx1' server and subscribe to all "control" topics from EMQX.
|Node||Node name||Listening port|
Configuring Mosquitto's bridging requires modifying the
mosquitto.conf file after installation. For each bridge, the basic content that needs to be configured is:
mosquitto.conf file and add a
connection to create a new bridge. The string after the
connection keyword is also the client id used on the remote node:
The MQTT protocol version used by Mosquitto bridge defaults to 3.1, and the 3.1.1 protocol needs to be specified in the configuration for use.
The configuration format of the bridged topic is
topic topic mode direction QoS local prefix remote prefix, which defines the rules for bridging forwarding and receiving. among them:
The following configuration example adds two bridging rules:
topic sensor/# out 1 topic control/# in 1
After the configuration is complete, Mosquitto needs to be restarted to make the bridge configuration take effect.
After the EMQ X MQTT server is installed, in order to make the Mosquitto bridge accessible, it is necessary to decide whether to configure the corresponding user certification and authentication information. Or in the experimental phase, in order to simplify testing, anonymous login is allowed and acl_nomatch can skip certification and authentication.
We use the
mosquitto_pub tools to test if the bridging configuration was successful.
Subscribe to the 'sensor/#' topic on 'emqx1', which will receive data reported by Mosquitto:
$ mosquitto_sub -t "sensor/#" -p 1883 -d -q 1 -h 192.168.1.100 Client mosqsub|19324-Zeus- sending CONNECT Client mosqsub|19324-Zeus- received CONNACK Client mosqsub|19324-Zeus- sending SUBSCRIBE (Mid: 1, Topic: sensor/#, QoS: 1) Client mosqsub|19324-Zeus- received SUBACK Subscribed (mid: 1): 1
Post a message on Mosquitto:
mosquitto_pub -t "sensor/1/temperature" -m "37.5" -d -h 192.168.1.101 -q 1 Client mosqpub|19325-Zeus- sending CONNECT Client mosqpub|19325-Zeus- received CONNACK Client mosqpub|19325-Zeus- sending PUBLISH (d0, q1, r0, m1, 'sensor/1/temperature', ... (4 bytes)) Client mosqpub|19325-Zeus- received PUBACK (Mid: 1) Client mosqpub|19325-Zeus- sending DISCONNECT
This message should be received on 'emqx1':
Client mosqsub|19324-Zeus- received PUBLISH (d0, q1, r0, m1, 'sensor/1/temperature', ... (4 bytes)) Client mosqsub|19324-Zeus- sending PUBACK (Mid: 1) 37.5
Subscribe to the 'control/#' topic on Mosquitto, which will receive messages posted on EMQ X:
$ mosquitto_sub -t "control/#" -p 1883 -d -q 1 -h 192.168.1.101 Client mosqsub|19338-Zeus- sending CONNECT Client mosqsub|19338-Zeus- received CONNACK Client mosqsub|19338-Zeus- sending SUBSCRIBE (Mid: 1, Topic: control/#, QoS: 1) Client mosqsub|19338-Zeus- received SUBACK Subscribed (mid: 1): 1
Post a message on 'emqx1', the message will be passed on 'emqx1' and bridged to Mosquitto local:
$ mosquitto_pub -t "control/1" -m "list_all" -d -h 192.168.1.100 -q 1 Client mosqpub|19343-Zeus- sending CONNECT Client mosqpub|19343-Zeus- received CONNACK Client mosqpub|19343-Zeus- sending PUBLISH (d0, q1, r0, m1, 'control/1', ... (8 bytes)) Client mosqpub|19343-Zeus- received PUBACK (Mid: 1) Client mosqpub|19343-Zeus- sending DISCONNECT
This message should be received on Mosquitto:
Client mosqsub|19338-Zeus- received PUBLISH (d0, q1, r0, m2, 'control/1', ... (8 bytes)) Client mosqsub|19338-Zeus- sending PUBACK (Mid: 2) list_all
The message retention function of [EMQ X MQTT Broker](https://emqx.io) is implemented by the `emqx_retainer` plugin, which is enabled by default. By modifying the configuration of the` emqx_retainer` plugin, you can adjust the EMQ X Broker's retention message Location, restrict the number of retained messages and maximum payload length, and adjust the expiration time of retained messages.
In March, the focus of our work was on finalising 4.3 release as well as the design of EMQ X Broker 5.0
[MQTT X](https://mqttx.app) is a cross-platform MQTT 5.0 desktop test client provided by the world's leading open source IoT middleware provider [EMQ](https://emqx.io) , which supports macOS, Linux, Windows. The user interface of **MQTT X** simplifies the operation logic of the page with the pattern of chatting software. Users can quickly create multiple simultaneous-online MQTT clients to test the connection/publish/subscribe functions of MQTT/TCP, MQTT/TLS and other MQTT protocol features.