Equality checks for NSIDs

[stevenbenitez]

The spec for NSIDs permits upper and lowercase letters for both the authority and name segments. Given that domain names are case-insensitive and generally normalized to lowercase, should the following two NSIDs be considered equal?

io.social.getFeed
IO.SOCIAL.getFeed

Are both of these legal NSIDs?

I assume that the name should be treated as case-sensitive, since it may identify a method and most languages will permit both getFeed and getfeed.

[bnewbold]

Good question! We are working on formalizing our NSID specification a bit.

Current thinking is:

• the "domain" parts should be normalized to lower-case (including when the NSID is embedded in an AT-URI)
• the "name" part is case-sensitive (should not be normalized)
• for equality and uniqueness checks, case can be ignored on the "name" part, and thus the NSID as a whole
• there "must" never be multiple schemas from the same authority that differ only by casing (though unclear how this is enforced technically)
• there "should" never be multiple collections in the same atproto repository (aka, account storage) that differ only by case (again, the burden of enforcement/implementation is unclear)

The NSIDs embedded in record paths, inside records, and inside AT-URIs inside records, are the most important parts to get correct.

[stevenbenitez]

Thanks for the detailed reply, @bnewbold! What you outlined sounds reasonable. I'll proceed with treating the example NSIDs in my original post as being equal (case-insensitive comparison).

[bnewbold]

We addressed these questions, at least indirectly, in an updated spec document: https://atproto.com/specs/nsid

Going to convert this issue to a discussion, as it is helpful to keep around!