MQTT in layman’s terms, best practices, use cases?

[rlkoshak (Rich Koshak)]

@Curtis

I’m using a Razberry with my Pi, would it be correct to assume that this will still work as it uses a serial port?

If it shows up as a /dev/tty device then it will work with socat/ser2net.

@Curtis

Would this mean that I would always need an internet connection to control my devices locally?

This CloudMQTT is what links the two OH instances together. Locally you will be talking to your OH directly and OH will be talking to your devices directly. But if there is no internet connection then your other OH will not be informed of these interactions.

@Curtis

The caravan is where I use SmarthThings with the Mosquitto broker. I assume I can send from this to CloudMQTT then to my main openHAB at home? I don’t make things easy for myself do I!

You can configure your SmartThings to use CloudMQTT or you can set up Mosquitto as a bridge and have it forward messages on certain topics to CloudMQTT.

@Curtis

Not sure I fully understand this approach. Do I install OpenVPN on both Pi’s then port forward through my router to connect them or something? Never used a VPN apart from to change my ip address sometimes.

A VPN is a secure way to make two LANs able to see each other over the Internet through an encrypted tunnel. You would install an OpenVPN server on one subnet and configure it appropriately which would include setting up a port forward to the OpenVPN server (usually 1194 I think). Then on your remote devices use the OpenVPN clients to connect to your OpenVPN server. You probably will want some sort of Dynamic DNS set up as well. Most midrange or better wifi routers will have OpenVPN built into them. I know for sure the Nighthawk series of routers do.

As an example, I have an OpenVPN server and I set up an OpenVPN client on my phone. So when I bring up the openHAB app it connects to the local address, not the remote myopenhab.org address because as far as my phone is concerned, it is on the same network as my OH server.

So if you set up a VPN connection between your remote LAN and your home LAN, all the computers on both LANs can see each other.

Another approach is to set up an ssh tunnel between your server and your home OH server. This is similar to the OpenVPN approach but ends up being a point-to-point solution. Rather than connecting your two LANs it only connects those two computers.