RE: [xri] XRD: Separating resource descriptions from authority

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

> > You can have a single <CanonicalID> but many <About>s.
>
> Ah, but only if the answer to one of your other questions is that one
> XRD can be about multiple resources, right?

Let's consider the different combinations:

* Multiple resources both point to the same XRD
* Multiple resources point to different XRDs with same exact content
* Multiple resources point to different XRDs

* Resource point to an XRD without any Abouts
* Resource point to an XRD with 1 About
* Resource point to an XRD with many Abouts

* An XRD contains no Abouts
* An XRD contains 1 About
* An XRD contains multiple Abouts

The subject of an XRD depends both on its content and how it was obtained. What is not clear is what we decide the semantic meaning of them. I doubt we will want to forbid a single XRD from describing multiple resources, if simply because that would require the presence of a single About in any XRD, and the deployment nightmare of managing movement of resource URIs.

There are many cases where a single resource is described by multiple URIs. To go and try to differentiate between URI aliases and URI pointing to different resources is never going to work.

So it seem to me that we are better off allowing these combination but making clear what they each mean. It might ok if we declare that resources listed in a single XRD could be considered equal. This is the practical conclusion of multiple URIs under a Link. But in the Link case, multiple URIs are not assumed to be the same, just to provide the same specific service. We cannot make this simple distinction at the XRD level.

An XRD can be about:

One resource with multiple URIs
One resource with a single URI
Multiple resources

Is there benefit to limiting this?

EHL