The protocol is called Eclipse uProtocol. Slide deck intro here:
https://docs.google.com/presentation/d/1yfJ_ynBGHQTcnG1GhyMQ...Protobuf, CloudEvents... Url based routing. Semi abstracted transport, atop http2, android binder, mqtt, amqp, and one I hadn't heard of DDS (Data Distribution Service, out of OMG).
Entity system. uTwin & uDiscovery are the two "core" entities. uSubscription uBus uStreamer and DPR are the communication layer entities. There's also uApps, Services, uDevices.
So each device seems to have a uBus. Attached are uApps (consumer), uServices (producer), a uSubscription, a uDiscovery, and a uStreamer. UStreamer connect device-to-device and/or device-to-cloud.