Yadis Spec .9 Change Proposal: Section 7.3.1 clarify multiple XRD

Drummond Reed drummond.reed at cordance.net
Thu Feb 9 19:28:21 UTC 2006

I'm actually sitting right next to Johannes at a conference today and was
able to clarify this with him as well.

Larry is correct, when an XRDS document contains a sequence of multiple XRD
elements, it is always the final XRD element that describes the target
resource (or, in YADIS terms, the target identity).

The reason for a sequence, BTW, is that each XRD can represent a different
subsegment of an XRI resolution path. For example, to resolve xri://@a*b*c,
the resulting XRDS document from an XRI resolver would contain 3 XRDS, one
from the @ authority for *a, one from the @a authority for @a*b, and one for
the @a*b authority for @a*b*c.

=Drummond (http://xri.net/=drummond.reed) 

-----Original Message-----
From: yadis-bounces at lists.danga.com [mailto:yadis-bounces at lists.danga.com]
On Behalf Of Larry Drebes
Sent: Thursday, February 09, 2006 8:45 AM
To: yadis at lists.danga.com
Subject: Re: Yadis Spec .9 Change Proposal: Section 7.3.1 clarify multiple

I think we should take a position.  It is worthwhile to have all 
implementations do the same thing when presented a document containing 
multiple <XRD> elements.   I believe the strategy of ignoring all <XRD> 
elements except the last came from Drummond's post 
http://lists.danga.com/pipermail/yadis/2005-December/001886.html .

If this is the correct behavior (Drummond?), then I think we need a 
wording change.


Johannes Ernst wrote:
> Are we certain that we want to have a position on this issue at all?
> The way your change request sounds is that different compliant 
> implementations can choose data from different sections (e.g. if there 
> is a higher-priority element in a non-last XRD), I don't think that is 
> what we mean.
> What we have so far is unambigious, but on further reflection, maybe 
> we should not take a position.
> On Feb 8, 2006, at 11:14, Larry Drebes wrote:
>> In section 7.3.1
>> The sentence
>> If a YADIS XRDS includes more than one XRD element, a Relying Party 
>> Agent MUST examine at least the last XRD element.
>> should be replaced with
>> If a YADIS XRDS includes more than one XRD element, the YADIS 
>> Resource Descriptor is the last XRD element. Other <XRD> elements are 
>> ignored.
> Johannes Ernst
> NetMesh Inc.
>  http://netmesh.info/jernst

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