The much-awaited (by me, at least) Jack metadata API has arrived. This will allow us to easily achieve many new things with minimal/nonexistent API friction. One of the simplest and most obvious is pretty names for Jack clients and ports, so I've chosen this as the first thing to tackle (as part of a drive to get Patchage polished up for a much overdue release).
Unfortunately, as far as I can tell, there is a chicken & egg scenario here since nothing is setting this metadata yet. So, I've made Jalv and Ingen both set pretty names for their ports. In the case of Jalv, the "pretty name" is the label given in the plugin data (distinct from the LV2 "symbol" which is restricted and unique).
Firing up Jalv with the Tal Dub III plugin (LV2 port courtesy KXStudio), we can see the port symbols, which are a bit awkward for end users with their prefixes and underscores. Conflating strong identifiers with human-readable labels is a serious design error I learned of the hard way, but that's a discussion for another time...
Enable "Human Names" in the view menu, or press C-h, and voilà, we see the pretty names set in Jack metadata (if present) instead.
The metadata API is very simple to use for ports, though there seems to be a hole in the API which makes it difficult to get the UUID for your client to set metadata (I want a simple jack_client_uuid, like jack_port_uuid, but it seems you have to get a string UUID and parse it to a jack_uuid_t, clunky enough that I just didn't bother). In any case, I am happy to see a low-friction mechanism in Jack which apps can use to share metadata towards making a better user experience.
It will be interesting to see what sort of information proves useful and becomes established/standard. For those of us of a mad scientist bent who live in a nest of patch cables, a CV tag seems like another obvious simple step, but for everyone, a big step is finally having meaningful port grouping and channel roles. I have always liked to joke that Jack (like LADSPA) doesn't really even do stereo, but with metadata, we can mark up stereo, 5.1, Ambisonics, etc., and other clients will be able to make sense of the channel assignments without resorting to dirty kludges based on guessing from names. All without changing the ABI one bit. Good stuff.