LinuxCNC controlled by Android

This is a first working test of a remote LinuxCNC UI running on supported Qt platforms like Android, iOS, Linux, Windows, ..

The final goal is to be able to run a full LinuxCNC control including stepperdrives on $50 worth of hardware, namely a cheap Cortex-A8 computer such as Raspberry Pi Zero, Raspberry CM1, i.MX51/AM335x-based hardware, etcetera. Just because we can.
Another nice application is the ability to use this as a secondary UI screen.

Now, how does this work? On the LinuxCNC side there is a server process that connects to the LinuxCNC Python interface. This process translates the error, status and command channels to JSON data which is posted/read to an MQTT broker over a secure socket.
The client also connects to the broker over a secure websocket, and the two parties are able to exchange status and commands.

Advantage of this approach over a pure socket is that the broker can be anywhere, and so can the clients. Thus, it also works flawless on a phone using a 3G/4G connection. Also, MQTT provides basic quality of service, it is lightweight and fast, you can have as many UI's running as needed.
It is also very easy to enhance functionality by designating different MQTT topics for different functionality. A separate webcam server process on the LinuxCNC machine could dump image data to a /webcam topic, and on the client side a separate viewer can extract this information without interfering with a webcam-unaware GUI.

Please forgive the crude layout, my experience with Qt is only a few hours.