> ... and have no ability to generate messages the other can consume, because they're completely different devices, from different manufacturers, with different

> ... and have no ability to generate messages the other can consume, because they're completely different devices, from different manufacturers, with different protocols? Even if the fridge wanted to tell the smart lightbulb to turn on when the door is open, they need a shared "lightbulb control protocol", no? That is what a message broker [1] is for. [1] https://en.wikipedia.org/wiki/Message_broker https://en.wikipedia.org/wiki/Message_broker