I forked an abandoned implementation of MQTT for SWI-Prolog by olsky, my fork is at https://github.com/sprior/swi-mqtt-pack https://github.com/sprior/swi-mqtt-p

I forked an abandoned implementation of MQTT for SWI-Prolog by olsky, my fork is at https://github.com/sprior/swi-mqtt-pack https://github.com/sprior/swi-mqtt-pack Look in the examples directory for some basic pub/sub code. The Prolog code that runs in my house is pretty specific to my house so I figured the best way to open source things would be as a framework more than an implementation. You can contact me via issues on the github repo and prod me into adding some more advanced examples - I've learned a lot since my last commit on the repo. I've started using the Redis functionality recently added to SWI-Prolog, so my code now responds to MQTT messages and uses state queried from Redis to help determine what actions (implemented by sent MQTT messages) to send out. The beauty is that since I don't do anything that blocks significantly in the Prolog code it is now single threaded - even the MQTT listening. It still responds quickly enough and is MUCH easier to deal with than multi-threaded. An example of what I'm doing is I built a bunch of ESP8266/EESP32 display devices that control neopixels/OLED/LCD displays. When one of those devices boots it sends a MQTT message announcing its location and capabilities (display type, bit depth, dimensions). Prolog receives that message and then stores that info in Redis. So that device info is all dynamic. So then later Prolog might get a notification that something is in the driveway. All by MQTT it requests an image from the appropriate camera, then sends the image off to Sighthound and deepstack image recognition servers. The Sighthound front end sends a message back to Prolog with a description of any vehicle spotted which Prolog then matches against known vehicles. If it determines for example that a Fedex truck is in the driveway then Prolog sends notifications around the house - it queries all the display devices from Redis and then based on the capabilities of each devices creates a JSON formatted MQTT message to send to each announcing the Fedex truck. It then also sends a MQTT message to some Java code that connects with Google and sends a push message to an Android app I wrote that displays the alert on my phone and watch. Before I switched to MQTT I was using Prolog with CORBA as the message transport and back then I also had Visual Basic and MS Agent as part of the system. One night I got bored and a little while later had 3 Peedy the Parrot characters singing Row Your Boat in a round across three different computers coordinated by Prolog. It was actually only a page worth of custom Prolog code for that.