2. Installation

2.1. Download

Get the library from the PyPi repository with the pip command, preferably using the --user option:

pip install --user mqttgateway

Alternatively use the bare pip command if you have administrator rights or if you are in a virtual environment.

pip install mqttgateway

Running pip also installs an executable file (exe in Windows or executable python script in Linux) called dummy2mqtt. It launches the demo interface dummy with the default configuration. Its location should be %APPDATA%\Python\Scripts\dummy2mqtt.exe on Windows and ~/.local/bin/dummy2mqtt on Linux (it probably depends on the distribution though…). If not, please search for the file manually.

Also, those same locations should be already defined in the PATH environment variable and therefore the executable should launch from any working directory. If not, the variable will have to be updated manually, or the executable needs to be specified with its real path.

2.2. Configuration

A configuration file is needed for each interface. In the library, the default interface dummy has its own configuration file dummy2mqtt.conf inside the package folder.

The configuration file has a standard INI syntax, as used by the standard library ConfigParser with sections identified by [SECTION] and options within sections identified by option:value. Comments are identified with a starting character #.

There are four sections:

  1. [MQTT] defines the MQTT parameters, most importantly the IP address of the broker under the option host. The address of the MQTT broker should be provided in the same format as expected by the paho.mqtt library, usually a raw IP address ( for example) or an address like test.mosquitto.org. The default port is 1883, if it is different it can also be indicated in the configuration file under the option port. Authentication is not available at this stage.
  2. [LOG] defines the different logging options. The library can log to the console, to a file, send emails or just send the logs to the standard error output. By default it logs to the console.
  3. [INTERFACE] is the section reserved to the actual interface using this library. Any number of options can be inserted here and will be made available to the interface code through a dictionary initialised with all the option:value pairs.
  4. [CONFIG] is a section reserved to the library to store information about the configuration loading process. Even if it is not visible in the configuration file it is created at runtime.

For more details about the .conf file, its defaults and the command line arguments, go to Configuration.

2.3. Launch

If pip installed correctly the executable files, just launch it from anywhere:


Launched without argument, the application looks for a configuration file in the same directory as the targeted script with the same name as the application, with a .conf extension. In this case, it finds the file dummy2mqtt.conf inside the package folder:

With the configuration provided, the application uses test.mosquitto.org as MQTT broker and will log messages from all levels only into the console.

Once started, the application logs a banner message and the full configuration used. Check here that all the options are as intended.

Then the log should show if the MQTT connection was successful and display the topics to which the application has subscribed.

After the start-up phase, the dummy interface logs any MQTT messages it receives. It also emits a unique message every 30 seconds.

Start your a MQTT monitor app (I use mqtt-spy). Connect to your MQTT broker (here it is test.mosquitto.org) and subscribe to the topic:


You should see the messages arriving every 30 seconds in the MQTT monitor, as well as in the log.

As the application has subscribed as well to this same topic testmqttgtw/dummyfunction/#, it receives back from the broker the same message it just sent, as can be seen in the log.

Publish now a message from the MQTT monitor:

topic: testmqttgtw/dummyfunction//kitchen//me/C
payload: audio_on

You should see in the log that the MQTT message has been received by the gateway, and that it has also been processed correctly by the mapping processor: a first log indicates that the MQTT message has been received by the mqttgateway library, a second log indicates that the internal message has been received by the dummy interface, with the changed (mapped) values of the various characteristics.


When the application sends a message with a topic it has subscribed to (as above), it receives it back from the broker, as seen before. Indeed a log showed that the MQTT message was received by the library. However, because of a feature that silences echo messages (via the sender characteristic), the library stops the message and does not send it to the dummy interface. That is why there is no second log in that case.

2.4. The mapping data

The mapping data is an optional feature that allows to map some or every keyword in the MQTT vocabulary into the equivalent keyword in the interface. This mapping is a very simple many-to-one relationship between MQTT and internal keywords for each characteristic, and its use is only to isolate the internal code from any changes in the MQTT vocabulary.

For the dummy interface, the mapping data is provided by the text file dummy_map.json. It’s just there as an example and it is enabled in the configuration provided. If you send MQTT messages with MQTT keywords from the mapping file, you should see their translation in the logs.

Note that the map file also contains the root of the MQTT messages and the topics that the interface should subscribe to.

For more details on the mapping data, go to Description.

2.5. Deploying a gateway

The objective of developing a gateway is to ultimately deploy it in a production environment. To install a gateway as a service on a linux machine, go to Configuration.