multiple URI elements per Service in XRDs

Martin Atkins mart at
Sat Jan 21 02:16:50 UTC 2006

Johannes Ernst wrote:
> It appears to me, that there is not requirement (aka MUST):
>  - that an implementation faithfully follow the priority attributes  at all

This requirement falls into that frustrating sub-category of MUST where
you really wish implementors would do it but in practice they don't lose
anything by ignoring it completely.

If I'm lazy and I write a relying party which just picks the first
acceptable service it sees, completely discarding priority, then it's
only the server end that suffers. Therefore there's nothing pressuring
me to do the right thing.

I guess what I'm describing is the difference between "You MUST do this
or it won't work" and "You MUST do this or we'll glare at you for not
doing the right thing". The latter case is still worthwhile because it
provides advise to implementers, but everyone must still be ready to
deal with people who ignore the requirement. In this case, I guess the
practical upshot of this is that in a case where several items share the
same priority the first is more likely to get picked, and users should
be aware of this when writing their YADIS documents.

All the best,

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