Cannot CMake on Linux with latest SDK Installed

[jwise-mfg]

Environment (please complete the following information):

• OS and Version: Ubuntu 20.04.3 LTS
• IDE used: no
• PLCnext Technology:
  • Firmware Version: 2021.9.0 (21.9.0.40)
  • PLCnext Engineer: 2021.0.3

Following instructions here: http://plcnext-runtime.com/ch01-04-installing-a-software-development-kit.html Installed plcncli, version: 21.6.0 Installed SDK, version: AXCF2152, 2021.9

Running CMake fails

• Per readme, ran cmake -G "Ninja" cmake -G "Ninja" -DCMAKE_TOOLCHAIN_FILE=/opt/pxc/sdk/AXCF2152/2021.9/toolchain.cmake -DBUILD_TESTING=OFF -DUSE_ARP_DEVICE=ON -DCMAKE_STAGING_PREFIX=/home/me/Projects/MqttGdsConnector/bin/axcf2152 -DCMAKE_INSTALL_PREFIX=/usr/local -DCMAKE_PREFIX_PATH=/home/me/Projects/MqttGdsConnector/external/deploy/axcf2152 -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DARP_TOOLCHAIN_ROOT=/opt/pxc/sdk/AXCF2152/2021.9 -DARP_DEVICE=AXCF2152 "-DARP_DEVICE_VERSION=2021.9.0 (21.9.0.40)" -S . -B ./build/axcf2152-2021.9

• Error is:

  
  CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
  Please set them or make sure they are set and tested correctly in the CMake files:
  Mqtt_Client
  linked by target "GdsConnector" in directory /home/me/Projects/MqttGdsConnector

-- Configuring incomplete, errors occurred!

**Improvement Request:** 
Update the sample build command to include the Mqtt_Client variable to avoid this error
![CMakeError](https://user-images.githubusercontent.com/57234292/139356632-bb5a0eac-595e-4e5a-92ff-e18be30b560b.png)

Trying to build output of https://github.com/PLCnext/MqttClient#building-from-source led to a build error for that project, which I have filed as https://github.com/PLCnext/MqttClient/issues/9

**Also fails when running tools scripts:**
The `tools\build-component.sh` script fails with the same error.

**Expected behavior**
Should be able to build as [instructed in this repo](https://github.com/PLCnext/MqttGdsConnector#building-from-source).

**Additional context**
Also tried on Windows, but couldn't even get this far.

[martinboers]

Hi, sorry for the delay.

Unfortunately we have not updated this project for some time, so I am afraid that it has fallen behind developments in the PLCnext Control firmware and SDKs.

We have decided not to maintain this project, since (a) the general concepts demonstrated here are now also demonstrated in other repositories, (b) it will not be possible in the forseeable future for users to develop their own RSC services for the PLCnext Runtime, and (c) there are now a number of alternatives for users who require MQTT Client functionality in their PLCnext Control projects.

I have now added a note to the top of the README, which we should have done some time ago (sorry).

If there is a particular reason that you need this specific component for your project, please let know.