Re: synonyms and property versions (was: Re: [xdi] Groups

Subject: Re: synonyms and property versions (was: Re: [xdi] Groups - XDI GraphPatterns 2011-06-23 - PDF (xdi-graph-patterns-2011-06-23.pdf) uploaded)

On Wed, Jul 6, 2011 at 1:04 AM, Giovanni Bartolomeo <giovanni.bartolomeo@uniroma2.it> wrote:

Hello Drummond, some first comments...

1- synonyms; looks like the primary/secondary synonym mechanism has disappeared, however there is a sentence saying "a $is relational arc on any context node requires XDI processor to redirect to its target node". What do you mean exactly?

Yes, I can't remember exactly in which version of the XDI Graph Patterns document we made the change, but the proposal was to solve the canonical synonym problem by: a) making $is unidirectional, and b) requiring XDI processors encountering a $is statement to redirect to the target node of the $is statement before continuing to traverse the graph.

So, for example, using the diagram on slide 3 of the 2011-06-23 version of the document, if an XDI processor was given the XDI address:

=abc+pea-patch

...it would "resolve" =abc to =!0999.a7b2.25fd.c609 before resolving +pea-patch to =!0999.a7b2.25fd.c609!1. I use the word "resolve" because the XDI processor is essentially resolving each XRI to the target XDI node that the XRI is intended to identify after evaluating synonyms. This process, which we spent 2 years working through in XRI resolution, makes it efficient to traverse a graph that may contain an unknown number of synonyms.

2- in the "Simple Properties" diagram, I think that the !2 arc from node =abc+age$v should point to the node =abc+age; that is, we are talking about the second version of the property, not of its value.

No, we are talking specifically about the second version of the property value.

The first version, =abc+age$v/!1! , has the value "32". The second version, =abc+age$v/!2!, points to the object (=abc/+age!), which has the value "33"

Likewise, in "Complex Properties", node =abc+tel$v should have an arc labelled !2 whose target is node =abc+tel, I think

Because it is a complex property, the versioning subgraph instantiates each version as a context node. So the first version of =abc+tel$v is =abc+tel$v!1. At that context node you would find an exact "snapshot" of =abc+tel at its first version state. The second version is =abc+tel$v!2. Because that is the current version, we don't need to place a snapshot of =abc+tel at that location of the graph, but can simply reference the current version, which is why there is a $is arc from =abc+tel$v!2 to =abc+tel.

=Drummond

Def. Quota drummond.reed@xdi.org:

PDF of previous file.

-- Drummond Reed

The document named XDI Graph Patterns 2011-06-23 - PDF
(xdi-graph-patterns-2011-06-23.pdf) has been submitted by Drummond Reed to
the OASIS XRI Data Interchange (XDI) TC document repository.

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http://www.oasis-open.org/committees/document.php?document_id=42654

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