For a long time. I didn’t know about “connection”, which is a fantastic library for writing clients with a specialized genserver-like behaviour. If you’ll eventually need tcp and tls, I recommend “transport”, which is a library I wrote that abstracts the difference between tcp and tls and makes it so you can seamlessly transition between one and the other.

This is the place to start to learn: Buckets of Sockets | Learn You Some Erlang for Great Good!

You’ll have to switch between erlang and elixir (a good exercise in and of itself) and I recommend writing a generic udp client/server pair and then a tcp client/server pair on localhost, then you can graduate to your application.

I would also recommend first learning by using active: true sockets (packets get turned into messages) and if you want, later learn active: false sockets. I think active: false sockets are better but active: true sockets are simpler.

Usually there should be a documented line protocol that defines what kinds of bits and bytes you send across the wire, and in what order, to indicate various intents. It might be a custom binary format, something like Protobufs, line-separated JSON, etc. There are all kinds of answers there and they all get handled a little differently. I think only the vendor you’re trying to integrate with can answer the initial part of this question for you.

:gen_tcp erlang module is useful for this. I’ve written several tcp protocols using it, it’s not terrible.