Use case: <br><br>I have 1M user accounts, each identified with a URI.<br><br>I follow each URI to its associated XRD when I want to find out metadata about that resource.<br><br>If I can do 2 things, I can avoid needing to publish (and digitally sign!) 1M XRD documents, by creating a "template XRD":<br>
(1) My URIs inside the XRD can contain {uri}<br>(2) {uri} means, in this context, "The Subject of this XRD"<br>(3) My XRD has no Subject element, so I use as its Subject the URI (user account) I started discovery on.<br>
<br>I can then sign exactly one document (the "template" XRD), and point to it from all of my 1M resources. I mark it as cacheable for 1 week and it is used for billions of metadata lookups without any HTTP overhead. Life is good.<br>
<br>(This is a profile of using XRD + templates of course, but a reasonable one suggested to me by Breno.)<br><br><div class="gmail_quote">On Thu, Nov 5, 2009 at 3:30 PM, Manger, James H <span dir="ltr"><<a href="mailto:James.H.Manger@team.telstra.com">James.H.Manger@team.telstra.com</a>></span> wrote:<br>
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<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Hi Santosh,</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
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<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">> </span>You are assuming the meta-data "is not a resource".<span style="color: rgb(31, 73, 125);"></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
</div><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">No I am not.</span></p><div class="im">
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">></span> I think meta-data is also a "Resource".<span style="color: rgb(31, 73, 125);"></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
</div><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I agree, the jim.footy.xrd file has its own URI so it is a resource — but that is irrelevant to <Subject>.</span></p>
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<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">The XRD <Subject> element “provides the identifier of the resource
<b>described by</b> this XRD” [<a href="http://www.oasis-open.org/committees/download.php/34724/xrd-1.0-wd09.html#element.xrd" target="_blank">XRD v1.0 WD9, §2.1.1.</a>].</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">jim.footy.xrd does not describe itself, it describes hundreds of other *.html pages I wrote about football. It makes no sense for <Subject> to hold the URI
of the XRD file itself in this situation.</span></p>
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<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">If you have an OpenID identifier that isn’t used for anything else (eg its not your blog or home page), then (in some potential future OpenID v3) a GET on
that OpenID identifier could return a XRD with its own URI in the <Subject>. It would be metadata about itself. It could point to an OP directly, eliminating the extra round-trip of going from a resource to its metadata since they are one and the same in this
case. [Mind you, I’m not sure you gain much over serving an HTML page with OpenID v1 or v2 <link>s to the OP.]</span></p>
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<p class="MsoNormal" style="margin-bottom: 12pt;"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="FR">James Manger</span></p>
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