{"id":7556,"date":"2017-12-14T23:31:00","date_gmt":"2017-12-15T04:31:00","guid":{"rendered":"https:\/\/rud.is\/b\/?p=7556"},"modified":"2018-03-07T16:45:02","modified_gmt":"2018-03-07T21:45:02","slug":"inter-operate-with-mqtt-message-brokers-with-r-a-k-a-live-bbc-subtitles","status":"publish","type":"post","link":"https:\/\/rud.is\/b\/2017\/12\/14\/inter-operate-with-mqtt-message-brokers-with-r-a-k-a-live-bbc-subtitles\/","title":{"rendered":"Inter-operate with ‘MQTT’ Message Brokers With R (a.k.a. Live! BBC! Subtitles!)"},"content":{"rendered":"

Most of us see the internet through the lens of browsers and apps on our laptops, desktops, watches, TVs and mobile devices. These displays are showing us — for the most part — content designed for human consumption. Sure, apps handle API interactions, but even most of that communication happens over ports 80 or 443. But, there are lots<\/em> of ports out there; 0:65535<\/code>, in fact (at least TCP-wise). And, all of them have some kind of data, and most of that is still targeted to something for us.<\/p>\n

What if I told you the machines are also talking to each other<\/em> using a thin\/efficient protocol that allows one, tiny sensor to talk to hundreds — if not thousands<\/em> — of systems without even a drop of silicon-laced sweat? How can a mere, constrained sensor do that? Well, it doesn’t do it alone. Many of them share their data over a fairly new protocol dubbed MQTT<\/a> (Message Queuing Telemetry Transport).<\/p>\n

An MQTT broker<\/em> watches for devices to publish<\/em> data under various topics<\/em><\/a> and then also watches for other systems to subscribe<\/em> to said topics and handles the rest of the interchange. The protocol is lightweight enough that fairly low-powered (CPU- and literal electric-use-wise) devices can easily send their data chunks up to a broker, and the entire protocol is robust enough to support a plethora of connections and an equal plethora of types of data.<\/p>\n

Why am I telling you all this?<\/h2>\n

Devices that publish to MQTT brokers tend to be in the spectrum of what folks sadly call the “Internet of Things”. It’s a terrible, ambiguous name, but it’s all over the media and most folks have some idea what it means. In the context of MQTT, you can think of it as, say, a single temperature sensor publishing it’s data to an MQTT broker so many other things — including programs written by humans to capture, log and analyze that data — can receive it. This is starting to sound like something that might be right up R’s alley.<\/p>\n

There are also potential use-cases where an online data processing system might want to publish data to many clients without said clients having to poll a poor, single-threaded R server constantly.<\/p>\n

Having MQTT connectivity for R could be really interesting.<\/p>\n

And, now we have the beginnings of said connectivity with the mqtt<\/code>? package<\/a>.<\/p>\n

Another Package? Really?<\/h2>\n

Yes, really.<\/p>\n

Besides the huge potential for having a direct R-bridge to the MQTT world, I’m work-interested in MQTT since we’ve found over 35,000 of them on the default, plaintext port for MQTT (1883) alone:<\/p>\n

\"\"<\/a><\/p>\n

There are enough of them that I don’t even need to show a base map.<\/p>\n

Some of these servers require authentication and others aren’t doing much of anything. But, there are a number of them hosted by corporations and individuals that are exposing real data. OwnTracks<\/a> seems to be one of the more popular self-\/badly-hosted ones.<\/p>\n

Then, there are others — like test.mosquitto.org<\/code> — which deliberately run open MQTT servers for “testing”. There definitely is testing going on there, but there are also real services using it as a production broker. The mqtt<\/code> package is based on the mosquitto C library<\/a>, so it’s only fitting that we show a few examples from its own test site here.<\/p>\n

For now, there’s really one function: topic_subscribe()<\/code>. Eventually, R will be able to publish to a broker and do more robust data collection operations (say, to make a live MQTT dashboard in Shiny). The topic_subscribe()<\/code> function is an all-in one tool that enables you to:<\/p>\n