This is an altered version of a technical test I completed as part of an interview process.
The premise was that I needed to demonstrate my ability to learn new concepts, and implement both a front and a back end of a simple system. This project was written in python, this was my first time using python.
The system requires a random number to be published over the MQTT protocol. MQTT is a publish-subscribe messaging framework. For this test two consumers were required. One was a web application, that would resize an SVG in response to the magnitude of the published number. The other was a command line application that would print the published output to the terminal.
I broke the python component of this project down into a QueueClient class and two scripts, Producer.py and Consumer.py.
The random number generator is included in the publish method on the QueueClient class. If it was any more complex than one line I would have put it in a separate file and imported it in but thought that was overkill in this case.
I've included relatively detailed commit messages demonstrating my thinking.
I've used RabbitMQ as my message broker, and paho MQTT as the MQTT client library for both the python and javascript components of this project.
These following instructions assume you are using a UNIX based system.
I am running a local instance of rabbitmq for this project. To set one up for yourself install rabbitmq. For debian users: sudo apt install rabbitmq-server. Then we need to enable a few plugins via rabbitmq-plugins enable rabbitmq_mqtt rabbitmq_web_mqtt.
To start rabbitmq use the command rabbitmq-server and stop the process with <CTRL C>.
Once you have your rabbitmq process running, from the root of this project run start.sh. It should already have the correct permissions, however if it does not run chmod +x start.sh.
This will start the both the Producer.py and Consumer.py scripts as background processes. You will see the output of Consumer.py (namely the random number read from the MQTT topic in the message broker)
This means you will not be able to stop the process with <CTRL C>as normal. To stop these processes find their process id with ps | grep -E "(Producer|Consumer).py" and use the kill command to terminate them.
To test the web application all you need to do is open the file ./web-app/index.html in your browser of choice while the python applications are running.