[Atp] Opening the AT URI (at://) Syntax Discussion

[Bryan Newbold <[e-mail]>]

Hi folks,

I want to kick of a thread to discuss the AT URI syntax, and in particular
the use of DID syntax (with multiple colons) in the "authority" part of the
URI. This group is chartered to formalize the "at://" URI scheme in a
standards-track document. But the currently deployed URIs (with billions of
strings in the wild) are unfortunately not strictly valid under RFC 3986.

I recently wrote a blog post about the situation[0]:
https://bnewbold.leaflet.pub/3mph4hzvbdc2v

Here is an example URI:  at://did:plc:vwzwgnygau7ed7b7wt5ux7y2/
app.bsky.feed.post/3k5nobkf2w72g

Here is the current AT URI syntax specification (which will form the basis
for a URI scheme I-D) as an informative reference:
https://atproto.com/specs/at-uri-scheme

I provisionally registered the "at" URI scheme with IANA back in 2023:
https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml

One path forward would be to "move the mountain" and try to change the IETF
URI syntax rules to be more permissive about the "authority" part. This
would make the current AT URI syntax valid. I assume this would be
difficult, but could be a positive contribution to the broader internet
ecosystem in the long run.

Another path forward would be coming up with a variant syntax or encoding
which is valid under the current rules. Realistically, the existing syntax
would need to be supported indefinitely in "legacy" form. For example,
replacing colons in DIDs with dashes ( at://did-plc-abc123/... ).

--bryan

[0]: I'm not sure what the etiquette is, but i'd be happy to copy/paste
this long-form blog post in to an I-D or on to this mailing list if helpful