I think we are on the same page here. NR, either in a function node or a custom node, can do the job without having to use mqtt/http/websockets/whatever to communicate with another process.
Something that works well in this sort of situation is the Map data structure (a not-as-well-known-as-it-should-be feature of ES6), which makes it easy to add, update, and delete objects. The map can saved in a context variable and made persistent over restarts. There is an example in the function node I posted in another thread.
