Not downvoting, but those two links don't really describe much - though they are part of the story.
For other readers, here's a general takeaway -
- Arrow Plasma was deprecated, and is now no longer even present in the Arrow project.
- The maintainers behind the Plasma store in Arrow forked it, into Ray. Plasma is still alive and well in Ray - and it still uses the Arrow IPC format, among other things. In addition to the links from the above poster, read the original blog post on Plasma [0], and the section on Ray on [1].
I use Ray quite a bit. For more lightweight stuff, or for more low-level control, I use Arrow Flight [2] (and [3] for Python examples)