-----Original Message----- From: Drummond Reed [mailto:drum...@cordance.net] Sent: Tuesday, January 27, 2009 10:00 PM To: 'XRI TC' Subject: [xri] Thoughts on XRD-to-resource cardinality

I will be offline Thursday and Friday travelling to a memorial, so I want to contribute here on the list to advance today's discussion about XRD-to-resource mapping (http://wiki.oasis-open.org/xri/SelfServeAgenda#head- a4044b7035eb441c2674549 d07ccaf27daed8970).

As I said on the call, the concept of a one-to-many mapping between >> an XRD and the resources it describes is a mind-expander for those of us who have been living a one-XRD-to-one-resource worldview for a few years now. But the use case -- being able to get and cache one XRD to describe >> potentially a very large number of resources (such as an entire site) is >> compelling.

Under a one-to-many mapping, I believe Eran's right that the >> concept of asserting a synonym (not just CanonicalID but any synonym) pretty >> much goes away. The only synonym assertion I could see providing is some form >> of aliasing template that would apply to the URIs of all the described resources (e.g., every that maps to the http://foo.example.com/* template can all be mapped to the http://bar.example.com/* template).

But that appears to be of limited use, and probably not appropriate >> for assigning CanonicalIDs (which is usually a mapping from a >> reassignable to a persistent identifier).

But the rest of the XRD metadata and Link metadata still seems appropriate, i.e., it applies as much to an individual resource (one-to-one mapping) as it does to a group of resources (one-to-many mapping).

So what I'm wondering is if maybe there should be a clear way of indicating the cardinality of the XRD. In other words, a child element of the >> root XRD element that indicates whether it is it an individual XRD (one- to-one mapping) or a group XRD (one-to-many mapping).

If there was a choice between two mutually exclusive options for that child element, then all the other elements that are appropriate only for >> one or the other (CanonicalID, EquivID, URIMap, etc.) could follow as children of that element.

Here's a simple example using the element names <Resource> and <ResourceGroup>:

INDIVIDUAL XRD:

<XRD> <Expires>2009-01-01T08:30:00Z</Expires> <Resource> <CanonicalID>http://example.com/resource/1</CanonicalID> <EquivID>http://example.net/resource/1</EquivID> </Resource> <Type>http://example.com/type/profile_photo</Type>

<Link> <URI>http://example.com/resource/2</URI> <Rel>http://example.com/rel/profile</Rel> </Link> </XRD>

GROUP XRD:

<XRD> <Expires>2009-01-01T08:30:00Z</Expires> <ResourceGroup> <URIMap>http://example.com/resource/*</URIMap> </ResourceGroup> <Type>http://example.com/type/photos</Type>

<Link> <URI>http://example.com/service/1</URI> <Rel>http://example.com/rel/some-group-service</Rel> </Link> </XRD>

Thoughts?

=Drummond

To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/ my_workgroups.php