I'm about to start implementing this sort of thing myself. We have a handful of webservices, an online store, a customer design tool and some third party connections to customers and suppliers. Then we have a factory of machines and operator stations that need to fetch and display information.

My thinking was to use something like Kafka, leaning towards NATS, as a big pub sub pipe.

I'm not looking for scaling. We are slow and don't need real time. What I need is uniformity. I don't want this connection to interface through FTP while that one is over a REST API. I'd prefer one connection for our main system and little interfaces to connect everything to the same pipe.