Minutes: XDI TC Call Wed. 7 December 9PM-10AM Pacific

Minutes of the unofficial XDI TC telecon 2005-12-07

Date: Wednesday, 7 December 2005 USA

Time: 09:00AM - 10:00AM Pacific Time

Dial-in number: 218-936-6666

Access Code: 2647893

PRESENT

Jason

Drummond

Andy

Owen

AGENDA

1) DISCUSS XDI TRIPLE TRIPLE MODEL

We discussed a potential proposal, inspired both by work on the "i-tag" initiative (see

http://www.seedwiki.com/wiki/itag/itag.cfm and in particular

http://www.seedwiki.com/wiki/itag/power_i-tags.cfm?wpid=220488) as well as

work on simple link contracts (as requested by Victor).

The proposal is that the XDI graph can be optimized not by just limiting it

to 3 levels deep, but also 3 levels "across". This means that everything in

the graph can be represented by an RDF "triple triple" -- a maximum of 3

linked RDF triples - a Subject triple, a Predicate triple, and an Object

triple. See the additional reference information appended below.

The group discussed the potential advantages of this model, principally that it would produce well-known "predicates" that enable parties to programmatically construct the XRIs representing the well-known XDI address of a data object in the context of a known contract in the context of a known relationship.

Before we could delve into this deeply we discussed how XRI resolution would work using XDI documents. This led into a long discussion about the type of XDI document that would be returned from a request to an XRI registry. We agreed that there should be a clear model for how XRI resolution is modeled using XDI documents, and that this should be documented by the XDI TC.

We concluded with an action item to create and post sample XRIs that would meet the "triple triple" or "3D" model for XDI addresses, particularly for link contracts. The goal is to do this before next week's call so we can continue the discussion then.

# ACTION ITEM – ALL: Compose and post sample XRIs that meet the constraints of the triple triple model.

=Drummond

***REFERENCE MATERIAL***

Following is an HTML excerpt from the early draft i-tag spec that explains the "triple triple" model in more detail:

I-tag syntax is based on the RDF "subject-predicate-object" statement model.XRIs are used to serializing these RDF statements because:

XRIs support the use of global identifiers within other global identifiers (i.e., XRIs within XRIs, or URIs/IRIs within XRIs) in order to express structured, cross-context relationships.

XRI syntax enables the persistent identification of the resources (people, organizations, dictionaries, media objects) participating in an i-tagging relationship.

As applied to tagging, the RDF + XRI model maps as follows:

Statement part	Usage
Subject XRI	XRI identifing the authoritative source of the tag
Predicate XRI	XRI identifing the tag used to describe the media object
Object XRI	XRI that identifing the media object being tagged

This RDF model is then applied recursively one layer deep, so each of the three XRIs above can also be expressed using its own RDF triple. This yields the following matrix:

	Subject	Predicate	Object
Subject XRI	XRI identifying the author asserting the i-tag (e.g. i-name or URL)	XRI identifying the type of tag source (e.g., a blog, website, album)	XRI identifying the instance of the tag source (e.g. a blog name, web page name, album name)
Predicate XRI	XRI identifying the author defining the i-tag (e.g. i-name or URL)	XRI identifying the type of tag (e.g., tag, license, rating)	XRI identifying the instance of the tag type (e.g., tag name, license name, rating no.)
Object XRI	XRI identifying the author of the media object (e.g. i-name or URL)	XRI identifying the type of media object (e.g. blog post, video, song)	XRI identifying the instance of the media object (e.g. blog post number, video name, song name)

xdi message