RE: [xri] What is this XRD is for?

[Eran Hammer-Lahav <eran@hueniverse.com>]

I'm trying to stay as far as possible from this conversation.

My point is only that only Subject defines what an XRD is about. Alias describes the subject. This is not some tricky logic and I agree that the terminology is bad, but while others may feel free to continue to debate this, any discussion that separates between representations and resources is not for me... :-)

But to explain what I meant:

<XRD>
    <Subject>Stephen King</Subject>
    <Alias>Richard Bachman</Alias>

    <Link rel='wife' href='Tabitha King' />
</XRD>

This XRD is only about Stephen King (who, BTW, is also known as Richard Bachman). Richard Bachman's (pretend) wife is Claudia Inez Bachman.

In other words, Alias describes the Subject, but it doesn't mean that everything about the Subject applies. To make it more technical:

<XRD>
    <Subject>http://hueniverse.com/eran</Subject>
    <Alias>acct:eran@hueniverse.com</Alias>

    <Link rel='copyright' href='http://creativecommons.org/licenses/by-nc-nd/3.0/us/' />
</XRD>

In this example, the link states that the copyright for the web page the Subject points to is a CC license. That link has nothing to do with the account URI in the Alias. In the context of WebFinger and identity protocols, the alias is useful, and these protocols may choose to use the information about my HTTP URI in connection with my account URI. XRD does not prevent this. But all you can learn from this XRD without knowing anything else about anything, is that the link's subject is the Subject, and that the Alias is another identifier for that resource.

Back to the dark hole of terminology, 'resource' can mean two very different things here (application specific, which only applies to what you do with the URI, not how you compare it): me the person or an HTML page with my biography. And (god!) no, I absolutely don't want to debate what the TAG, semantic web, or anyone really, thinks about this... :-)

EHL

> -----Original Message-----
> From: Scott Cantor [mailto:cantor.2@osu.edu]
> Sent: Thursday, February 04, 2010 5:02 PM
> To: Eran Hammer-Lahav; 'Breno de Medeiros'; xri@lists.oasis-open.org
> Subject: RE: [xri] What is this XRD is for?
> 
> Eran Hammer-Lahav wrote on 2010-02-04:
> > Can both denote the same resource but one uses HTTP and the other
> > ACCT. If an XRD has the HTTP in the subject, that's all the XRD is
> > about. If that
> XRD
> > also has the ACCT one in an alias, all it means is that the resource
> > identified by the subject can also be identified by the alias, but it
> > does not mean that the properties and links associated with the
> > HTTP-identified resource apply to the ACCT-identified resource.
> 
> I don't think you can make such a statement, and have it make any sense,
> unless you s/resource/representation. In other words, if the XRD is about
> the representation, you can plausibly say that even though the Alias is
> another URI for the same resource, the XRD content doesn't necessarily
> apply because the Alias could map to a different representation of the same
> resource.
> 
> But you seem to want to stick with the "resource" terminology, and then
> your argument falls apart, it seems to me.
> 
> -- Scott
>