2. Installation

2.1. Download

Get the library from the PyPi repository with the pip command, preferrably 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 UPDATE NEEDED HERE on Windows and UPDATE NEEDED HERE on Linux. If not, 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 dummy.

The configuration file has a standard INI syntax, 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 (192.168.1.55 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. It is not visible in the template files but 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:

dummy2mqtt

By default, the process will log messages from all levels into the console. It should start printing a banner message to indicate the application has started, then a list of the full configuration used.

If the MQTT connection is successful it should say so as well as displaying the topics to which the application has subscribed.

2.4. First Run

After the start-up phase, the dummy interface logs (at a DEBUG level) any MQTT messages it receives. It also emits a unique message every 30 seconds. Start your favourite MQTT monitor app (I use the excellent mqtt-spy). Connect to your MQTT broker and subscribe to the topic:

home/+/dummy/+/+/+/C

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

Publish now a message from the MQTT monitor:

topic: home/lighting/dummy/office/undefined/me/C
payload: LIGHT_ON

You should see in the log that the message has been received by the gateway, and that it has been processed correctly, meaning that even if it does not do anything, the translation methods have worked.

2.5. 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 one-to-one relationship between keywords of 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, as, once again, the dummy interface really doesn’t do anything, and it is disabledby default. 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 Concepts.

2.6. 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.