Thank you Riva.
I use ThinkSpeak's free services for historical analysis, trending and visualization among other things.
I also tried a free dynamic-to-static IP service, but it was too limiting really, returning HTML frames pages with advertising. Frames - argh!
The pi is nice but I was given an Arduino to start with and it grew into multiple Arduinos before long.
So the ESP8266 nodeMCU seemed a cheap addition for internet connectivity. I already had the website so adding a small API just made sense to me. And the ESP8266 is cheaper than the pi with less to learn since the nodeMCU is programable using the same Arduino IDE that I had already learned.
Also, like the pi, the nodeMCU can be used without the Arduino boards for small control system needs.
For existing Arduino control systems, adding an ESP8266 nodeMCU for internet connectivity is an easy and cheap solution, or so I think.
Thanks again,
Greg