Is MQTT Necessary? or, Use Case for MQTT?

[TRS-80]

Thanks for the clarification, @hek!

I think I have done just about as much research as is needed to select hub hardware, software, and sort of overall topology and protocols, etc... And I've already got several ideas for various nodes, of course!

Which means, time to order parts soon and start tinkering! I'm excited! :)

[UglyKidJoe]

@TRS-80, this topic is very interesting (so I though I would revive it :) )

I'm building my system based on Openhhab2 which it a pretty awesome framework to say the least. Immensely powerful.

Your post here touches on one area that I just can't get my head around - the link between OH2 on the Pi and Arduino RF boards. I'm probably missing something obvious but it's never been clear to me.

Admittedly I haven't set up any Arduino-based sensors yet but I'm hoping to start shortly (my dream is to build motion sensors as they are horribly expensive to buy manufactured (i.e. Aeotec etc)).

Have you bypassed MQTT or has it become integral in your workflow?

[gohan]

With OH2 you can use either serial gateway or mqtt. Mqtt allows you to have much more flexibility in terms of monitoring data or send data to your controller: for example if you want to tinker with sensor values for testing purposes, you could just power off sensor and send data you want using a simple mqtt client, or if you want to play around with multiple controllers you only need to configure them to subscribe to mqtt and they can run simultaneously. I've even seen a post about using zabbix to plot data from mqtt

[hek]

Sidenote: MySensors has a Node RED plugin available as well. It's also a good alternative for tinkering/route messages from a MySensors network. Even more flexible then a raw MQTT broker.

[UglyKidJoe]

@gohan

Thanks for the quick response.

It will be my first implementation of MQTT so I'm pretty much a blank canvas. I'll go with setting up the MQTT broker (server it's called now I believe) on my Raspberry Pi 3.

Installing OpenHAB2 on the Pi has been made a breeze by an unattended installer called OpenHABian. Bundled with the installer is an MQTT option which should set it up (it's accessed via a menu).

I'll be happy to share my lessons learned here, no doubt there will be a few :)

I've still got to order a few sensors and boards etc to get started so it will take a little while. That;s why I read this thread to get an idea of how the components all talk to each other. That would at least help me determine what I need to buy upfront so I can get busy with it. Any advice would be appreciated (just to get a motion sensor up and running)

I imagine it can become addictive!

[TimO]

For the OpenHAB users: take a look at the MQTT eventbus. This is really cool!
I'm using OpenHAB 2 with the MySensors binding and currently three serial gateways. From OpenHAB 2 the messages are send to the MQTT broker to Node Red.

So:
Serial gateway <-> OpenHAB 2 (with binding) <-> MQTT (Mosquitto) <-> Node Red

[gohan]

@UglyKidJoe
I started with openhabian too, but I figured it's too complicated to start with. So now I moved to domoticz that's much simpler for beginners: at the moment I'm only using one ethernet gateway for sensors but I am planning to move to mqtt later on, after I learned better how to make sensors nodes.

[UglyKidJoe]

@hek

This got me interested so I looked at Node Red. Wow! I started looking at some youtube intros and it looks very good. So let the learning curve begin :)

I suppose the first challenge will be to figure out how the architectures relate to one another.

Would I be able to use Node Red with the OH2 Z-Wave binding as well as mysensors for instance? Similarly, OH2 controls my WEMO lights, so they will also play with Node Red via OH2?

I know these are real noob questions but it would be a huge help to get set off in the right direction

[UglyKidJoe]

@TimO said:

So:
Serial gateway <-> OpenHAB 2 (with binding) <-> MQTT (Mosquitto) <-> Node Red

Interesting infrastructure. I would imagine there are endless possibilities with it. Thanks for the pointer :)

I got some homework to do on this, but looks like a helpful introduction video is here: here

[bgunnarb]

@UglyKidJoe
I have been using OpenHAB and MQTT for a number of years now.

The reason for using MQTT and not just a serial connection from the MySensors GW is partly the flexibility as many have stated previously here. Easy to test, using e.g. the mqtt.fx tool. If you want to know what is going on you simply connect to the MQTT stream and "snoop" on the messages.

Another reason is that I am running three geographical sites on one OH installation. OH is running on a NUC at my home. There is also an MQTT GW here. Two other My Sensors MQTT-GW are running remotely in two summer houses. The three GW connect over internet to a cloud-based MQTT broker and OH connects to the same broker. In that way I do not have to open any ports into my home network for access should I have had a local MQTT-broker at home.