Thanks to all who helped with the reverse question. I’d now like to stream data from node-red to a c program for use as input in computations. I’ll keep it simple. All I want is to inject a timestamp, stream it live to someplace I can access in my c program, then multiply it by 2 in c and stream i…

I dont think that can be solved as easy. Now you need the c to listen so you are back at square #1. TCP or MQTT...two way implementation in c seems the best for your needs Is this thing a hobby stuff or @work? If a business task you have been given, why not hire a c programmer as consultant?

It's both hobby and work, like a quantum superposition of states, but one that has me both excited and miserable all at once. Mostly miserable now that I'm doing C.

To start simple, I wonder if I can write from node-red to a file and read that file in C as it gets updated... then do my calculations in C and pass the results in to node-red... which would come for free if I'm running my C program using an exec node?

Or maybe I could output from node-red to stdin and use stdin as input in my C program, do my calculations, and pass the results to node-red (again with C running in an exec node)? This obviously wouldn't work if node-red and my C program are on different machines, but as a simple start, maybe it co…

Why not just use one of the prebuilt libraries and work around it for MQTT ? [image] Eclipse Paho | The Eclipse Foundation The Eclipse Foundation - home to a global community, the Eclipse IDE, Jakarta EE and over 375 open source projects, including runtimes, tools and frameworks. …

[image] craigcurtin: Why not just use one of the prebuilt libraries and work around it for MQTT Now we are full circle :smiley:

The node-red-node-daemon will help you here. It is like the exec node in that it runs your external program, but hooks the input to your stdin, so if your app listens to stdin it can get what you send it

You beat me to it Dave. I wanted to get a working example before I posted. So here it is, better late than never. [{"id":"a43a81bd.755b2","type":"inject","z":"8b280028.0371c8","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic"…

A simple question: If the c program runs on same machine, why do you not use N-API or NaN ?

I think the long term intention is not to run on the same machine.

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Stream data from node-red to c program?

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Steve-Mcl 19 February 2021 09:11 8

Now we are full circle

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Stream data from node-red to c program?

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