This software provides an MQTT interface to a set of usb-connected Brother QL label printers attached to a linux computer.

• Python >= 3.7
• Uses the brother_ql python package
• Connects to a single MQTT broker and performs all communication through it

For installing this on a raspberry pi, for example

git clone https://github.com/mattj23/brother-ql-mqtt.git
cd brother-ql-mqtt
pip3 install -r requirements.txt

# Edit the settings.json file to match your mqtt broker
# Don't forgot to set tls_cafile if you're using tls, otherwise you'll get
# all sorts of cryptic errors

# Edit the unit file to match your user and absolute path before
# you copy it to the systemd folder
sudo cp brother-ql-mqtt.service /etc/systemd/system/
sudo systemctl enable brother-ql-mqtt
sudo systemctl start brother-ql-mqtt
sudo systemctl status brother-ql-mqtt

The goal of this software is to provide a scalable backend for Brother QL label printers.

We have services which rely on the label printers, and have encountered a few issues in using them:

1. For whatever reason, the WIFI is unreliable at our office when a non-wifi system has to initiate communication with the wifi label printer
2. There isn't any obvious way to scale out the printers, since a central system has to know about them and maintain knowledge of their addresses
3. We don't really have a way of getting status info about the printers
4. IP addresses are going to become tight

The system is composed of two parts:

1. A scalable number of label servers, each being a linux machine with a number of USB connected printers
2. A central management server, which is an ephemeral service through which all consuming services make their printing requests

These are connected through the MQTT broker and pre-agreed topic names

• Label server host (the linux machine) starts the software service
• Checks what printers are attached
• Connects to MQTT broker
• Begins regularly publishing information on the connected printing devices
• Subscribes to command topics
• Performs commands as they are received

Concerns:

• Label printer is a single threaded resource, needs to be protected by some sort of queue
• Keep label server as simple as possible: changes here need to be deployed everywhere

• Add all complexity here
• Maintain a list of unique printer serial numbers, and be able to assign aliases to them