We’re currently working on putting JEP-0163: Simplified Personal Publish-Subscribe into Psi. A result of this work, together with an implementation of User Tune as our use case, can be seen in action here.
Since there is no SPPS server support yet, we still have to use the low-level PubSub protocol. However, the code is written such that an SPPS-like interface is used inside Psi, while the backend of the interface transforms the requests and events to and from PubSub services and nodes. This transformation makes use of a database of mappings, which has to be managed manually by the user. When SPPS is finally supported by servers, this transformation code can be removed from the backend, and publishing and receiving events will happen fully automatic.
Then there is still the issue of subscribing to nodes, which also has to be done manually at this time. Although SPPS has nothing to say about this, another JEP is being worked on to manage subscriptions, which should be the final brick for usable and easy-to-implement PubSub in clients.
Instructions on how to get it working can be found here.