I’ve connected a temperature & humidity sensor, a photoresistor, and a LED to an Ethernet shield plugged onto my Arduino Uno.
I’ve used a CoAP library and I’ve created an Arduino sketch. It connects to the internet and sends sensor readings to the cloud.
I may view them in the application or on a dashboard. I can also embed live measurements into an image and show it on any website (as I did with the schematic above).
The schematic and code can be found on GitHub.