mqtt_matlab_interface

MATLAB interface to MQTT, based on the Paho Java client. Updated versions of the Java client org.eclipse.paho.client.mqttv3-1.2.2.jar included in the jars directory can be found on this page.

Bare bones implementation which allows to connect to a MQTT broker (e.g. EMQ X Broker https://www.emqx.io/products/broker), publish and subscribe to multiple topics. The MqttInterface matlab class allows for an easy interface to the basic functionalities of MQTT-based message exchange. Besides strings and JSON messages, it is also possible to directly send and receive MATLAB objects.

Minimal test:

1. run a MQTT broker (e.g. in the case of EMQ X Broker: in a terminal, cd emqx_downloaded_folder/bin and run ./emqx start)
2. open MATLAB and run example.m
3. if the class iMqttClient is not found by MATLAB, follow step 2 below to recompile the Java source.

Extending functionalities:

1. the source file iMqttClient.java in the src directory can be modified to add the desired functionalities
2. a iMqttClient.jar file can be (re)generated as follows:

• javac is required for this to work (on Ubuntu 18.04, for instance, it can be installed through sudo apt install default-jdk)
• run version -java in the MATLAB command window to get the version of Java of your MATLAB installation (e.g. Java 1.8.0...)
• in a terminal, cd to the jars directory and run pack_to_jar.sh passing the MATLAB Java version as argument (e.g. sh pack_to_jar.sh 1.8)
• a file iMqttClient.jar should appear in the folder jars

3. the updated Java class packed in the iMqttClient.jar file in the jars folder can be then imported, together with its dependencies org.eclipse.paho.client.mqttv3-1.2.2.jar, in MATLAB using the javaaddpath command as done in example.m