An open discussion list for topics related to the eduGAIN interfederation service.

["Cantor, Scott" <cantor.2 AT osu.edu>]

After Peter brought the issue up to me, I reviewed the xml:lang rules, and 
the critical point to me is that an empty xml:lang tag does not mean "ignore" 
or "operate under a default" but rather "clear and unset any existing lang" 
and act as if it weren't present.

My opinion as the spec author is that that clearly violates the intention of 
the required inclusion of xml:lang for most of the metadata elements where 
it's defined. xml:lang="" would be treated identically to not having it, and 
that's not allowed.

The exception I ran into was Logo, where xml:lang is optional. It seems to me 
that while an empty xml:lang is clearly equivalent there to omitting it, 
that's an edge case. The code should probably be patched to allow it and 
treat those as the same if in fact it doesn't already (I didn't test it yet) 
but in the required cases, the outcome of denying the validity is IMHO 
correct behavior, even if the exact mechanics by which it's rejecting it are 
a bit odd.

I think allowing an empty lang in those cases is in fact a bug and I would 
not "fix" Shibboleth to allow it. I don't think eduGAIN has any good reason 
to allow it to appear anywhere, except perhaps Logo, and that's probably more 
work to carve out an exception for than any obvious benefit to me.

I'll file a bug to review the handling in Logo and anywhere else it shows up 
as optional. We have other SP patch work to do so it's relatively timely.

-- Scott