I want to make it easy to publish lists of books I am reading and have read, or any other list. And do so without using centralised platforms like e.g. Goodreads (Amazon). A book list is a small library.
The route I am currently on, is publishing a machine readable list others can easily incorporate. These lists are in OPML, an exchange format for outlines. It’s the same format generally used to share lists of RSS feed subscriptions.

Current situation and usage: automated lists
Currently I am able to directly automatically create the lists in OPML from my individual book notes in Obsidian.md (which I use for PKM).
In Q1 2022 I experienced that creating lists and posting them works nicely and smoothly, with no friction. I do currently only create a few lists (fiction and non-fiction in the running year, antilibrary). I’m also working through the books I’ve read in the last decade or so, and gradually creating those lists. I’m not generating those as OPML however, they currently are just a list in my own notes.

Next steps: consuming other lists
Next steps will look at how to do the federating itself: how can I ‘consume’, or even include in my own lists, the OPML, ActivityPub or JSON lists of others in a meaningful way? I think a first step is consuming one list published by someone else, treating it as a recommendation list perhaps or some other form of input, much like I’m reading feeds. It might be useful to be able to pick out mentions about books I’ve already read, are in my anti-library, match an author I like, or match my interests while being unknown to me. I suspect a slightly tweaked parser for every new list might be needed, as using a list depends both on format and on content fields.

Ealier steps: proof of concept and data model
In 2020 I came across a posting by Tom Critchlow on this topic, and a year later I started looking into using OPML to create the lists.

I created a proof of concept, with a data format.
Using that I created a webform to update a book list by hand with a new entry.
Then I automated generating the lists (code on GitHub).
All as proofs of concept.