XDI TC Minutes

Following are the minutes of the unofficial telecon of the XDI TC at:

Date: Friday, 01 November 2013 USA
Time: 09:00AM - 10:30AM Pacific Time (16:00-17:30 UTC)

ATTENDING

Dan Blum

Markus Sabadello

Animesh Chowdhury

Joseph Boyle

Drummond Reed

Les Chasen

REGRETS

Phil Windley

GUESTS

Andy Dale

NEWS & UPDATES

XDI at IIW #17 Report

We recapped what we learned at Internet Identity Workshop in Mountain View.

Drummond said that it made all the difference to show examples of how XDI actually works to solve a problem, because putting it in a specific problem context makes it much easier to understand.

Markus said that he is more convinced than ever of the need for higher-level tools and libraries to make it simpler for developers to adopt XDI.

PRESENTATIONS/DISCUSSIONS

Progress on Working Drafts

Drummond explained that his workload leading up to IIW meant that he simply could not finish his sections of XDI Core, despite the availability of Joseph’s sections.

Joseph said that he had made progress on his sections, and is now largely waiting on Drummond.

Markus reiterated that he has not been able to put time into Messaging spec due to all the work preparing to demonstrate link contract initiation for IIW.

Drummond concluded that as always it comes down to resource availability and allocation. He plans to work with Respect Network VP Development Andy Dale, who he invited to the call, to discuss how Respect Network might be able to provide more resources.

Inner Root Dependent Graphs and Why We Don’t Need Statement Roots

The solution to clarifying the relationship of inner roots to entity or attribute contexts was to define inner roots as “dependent graphs” of the associated XDI graph nodes. So an operation on any particular XDI node also affects all of its dependent graphs.

Markus gave a demonstration of how he implemented this in XDI2. He said that this does make the persistence mechanisms more complicated because a $del operation must walk the tree of subcontexts to find all dependent graphs.

To illustrate this, Markus gave this minimal example of an XDI statement based on an inner root:

Normal notation:

(=a/+b)=c/+d/(=a/+b)=e

Short notation:

=a/+b/(=c/+d/=e)

Example operation on a context containing an inner root:

../$get/=a

Complete set of result statements of operation:

()/()/=a

()/()/(=a/+b)

=a/+b/(=a/+b)

(=a/+b)/()/=c

(=a/+b)/()/=e

(=a/+b)=c/+d/(=a/+b)=e

As a result of this analysis of inner roots, Drummond explained that we no longer need the concept of “statement roots”. We only need 3 types of root nodes:

The outer root: empty parens, i.e., ()
Peer roots: an XDI subject in parens, e.g., (=markus)
Inner roots: an XDI subject and predicate in parens, e.g., (=markus/+friend)

Joseph pointed out that inner roots have an analogy to RDF blank nodes in that they are not addressable with simple paths but require other statements. However, unlike RDF, they are in XDI fully and uniquely addressable.

We then discussed this further by looking at diagrams prepared by Markus.

Drummond asked for feedback on a term to use to describe the relationship between the four “levels” or “layers” or “spaces” of context node types:

Roots
Entities
Attributes
Values

He and Markus gave this example of an XDI address containing all 4 types of context nodes:

<-- ROOT --><-- ENTITY --><-- ATTRIBUTE --><-- VALUE -->

(=markus)

[=]!:uuid:1111$public

<$key>

Joseph said he recommended against adding another new term to describe these four types of contexts. Markus pointed out that in his opinion it is more important to stress how much they have in common—that they are all context nodes—than their differences.

Drummond said he would think hard about it because while he agrees strongly about how much these four types of context nodes share by being context nodes, he also believes their differences are critically important, and important in a different way than the distinction between singletons and collections/members, or the distinctions between different types of root nodes (outer, peer, inner).