[StavrosK]

I've solved this problem for myself, and I suspect that many other people have it, but nobody has shown any interest in my solution so far:

https://github.com/skorokithakis/gweet

It's a command queue that allows your Raspi/Arduino to listen to commands and your control apps to issue them. I use secret keys for the commands, but you can also use crypto to sign the requests. It's been working very well for me, and with very low latency (the DNS query and TLS setup are the slowest parts, it seems).

[anonbanker]

posting as breadcrumbs. I'll need this in the next two months.

[StavrosK]

It should also be on the first page if you Google "message queue internet of things".

[williamjennings]

I have gone: spelunking in the deepest caves; and climbing on the tallest mountains; but my breadcrumbs always lead home.

https://www.youtube.com/watch?v=XybNecZc1nU