I’ve been working on finalizing a new version of an old draft for a CoAP pubsub broker.
The current draft is quite extensive, but it’s extremely straightforward to implement if you already have a CoAP implementation: A publish-subscribe architecture for the Constrained Application Protocol (CoAP)
I wrote a basic implementation, which you can check out here: GitHub - jaimejim/aiocoap-pubsub-broker: Implementation of draft-ietf-core-coap-pubsub
During the Hackathon, I’m hoping to test interoperability with other implementations. If this interests you, please reach out to me at my IETF email (listed on the draft).