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

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

> -----Original Message-----
> From: Breno de Medeiros [mailto:breno@google.com]
> Sent: Thursday, February 04, 2010 4:50 PM

> > I changed the spec to say "The <Subject> element contains a URI value
> which identifies the resource described by this XRD" to be more consistent.
> Enough?
> 
> I don't think so. This language can mean many things. We should make it
> explicitly that identifiers the resource in a scheme-specific manner.

That has nothing to do with it. The scheme-specific language is about comparing values, not about figuring out what a URI identifies (and it is still a TODO).
 
> Yes, I just meant here that the concept of <Alias> is identical as <Subject>,
> i.e., the rules to find out what resource is mentioned by an <Alias> element
> is the same as for a <Subject> element.

Yes.
 
> >
> >> My thoughts currently are that the resource is the equivalence class
> >> of URIs in a scheme-dependent way. My thinking is that these URIs are
> >> alternative representations of the same resource, and XRDs are
> >> meta-data about resources, not about a URI string.
> >
> > This discussion becomes useless very fast. XRD is about what the URI
> *identifies*.
> 
> "URI identifies" can mean a lot of things to a lot of people. I would like it to
> say what the "URI identifiers, in a scheme-specific manner"

Your language doesn't make it any better defined because scheme-specific can mean a lot of different things too. What if the URI is an XML namespace but can also be resolved to a web page with the XSD schema? The scheme-specific text helps when you need to consider normalization when comparing two strings that might be equivalent. It's all about a URI to URI comparison. When we talk about what a URI identifies, it is beyond application specific, it is philosophical...

All you should care about is how to compare two URIs, not how to interpret what each URI means. This only comes into play if you have an XRD and some resource you want more information about, and you want to know if that XRD is about that resource. You can also make this determination if you compare apples to apples, which means, you need to first know how to identify the resource, and that is, unless someone invents something new, a URI.

I don't think we are in any disagreement on this. A sentence clarifying that comparing subject values is scheme specific should solve your concerns (same for Alias).

EHL