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Subject: RE: [xri] GCS Characters
The GCS Delimiter proposal (http://wiki.oasis-open.org/xri/XriThree/GcsDelimiter)
goes into great depth about why XDI needs the level of precision provided by both
GCS delimiters and cross-references. Cross-reference syntax (syntactically
encapsulating identifiers by enclosing them in parentheses) is essential for
being able to put any identifier (a URI or an XRI) in another context. For
example, in my last message I showed how it could be used to indicate –
anywhere within an XRI – that a URI represented a resource in either a
personal or an organizational context: ...=(http://example.com/data/uri)... ...@(http://example.com/data/uri)... This isn’t something we want to give
up. At the same time, the extreme semantic precision
of XDI RDF (which is really to say the extreme semantic precision of any RDF
vocabulary compared to natural language vocabularies like English) also needs
to be able to express that a resource in one XDI global context can be referred
to directly within another XDI global context. That means the ability to
express any combination of the following XRIs: =example @example +example $example E.g.: @example+example +example$example @example+example$example @example=example =example@example In XDI RDF, all of these represent very
precise RDF statements about the relationship between two resources that can be
independently identified in a global context. Adding parens, stars, or bangs
would change those XDI RDF statements as explained at http://wiki.oasis-open.org/xri/XriThree/GcsDelimiter.
In conclusion, Les, I don’t think there
is any satisfactory answer to your question when you are looking at XRI syntax
from a natural language standpoint. To a human being, =drummond@microsoft.com
and =drummond*(@microsoft.com) don’t look that different. However to a
machine, they are different identifiers, and when you need the precision of a
semantic language like XDI RDF, this difference becomes critically important. On that score, for TC members who are not
intimately familiar with RDF, I did a blog post about a new book called Semantic
Web for the Working Ontologist: http://www.equalsdrummond.name/?p=164 I recommend it very highly because it does
such a good job at explaining to reasonably web-savvy technologists how RDF
really works and what kinds of problems in machine-understandable semantics it can
solve. =Drummond From: Chasen, Les
[mailto:les.chasen@neustar.biz] I continue to struggle with why we need two ways to put a
global xri in the context of another xri. =drummond@microsoft.com and
=drummond*(@microsoft.com) seem to do the same thing. If the later is less than
desirable let's drop ()'s in xri. From: Drummond Reed First, just to address some clarification
questions in this thread, the proposal under discussion, called GCS Delimiter,
is posted at:
http://wiki.oasis-open.org/xri/XriThree/GcsDelimiter The accompanying ABNF that implements this
proposal is at:
http://wiki.oasis-open.org/xri/XriThree/SyntaxAbnf
As described there in more detail, the
proposal is that in XRI 3.0, all GCS characters (=, @, +, $) are treated in XRI
syntax as delimiters just like * and ! are in XRI 2.0. Per the ABNF, both =drummond@microsoft.com
and @microsoft.com=drummond would parse into two subsegments. =drummond@microsoft.com
would parse into: 1) =drummond 2) @microsoft.com @microsoft.com=drummond would parse into: 1) @microsoft.com 2) =drummond =drummond+phone+home would parse into: 1) =drummond 2) +phone 3) +home In XRI resolution, each of these would produce
its own XRD. I don’t know why John thinks this is strange – an XRD
can describe any resource, and certainly my phone collection is a resource, and
my home phone is a resource. =Drummond From: John Bradley
[mailto:jbradley@mac.com] Well thats a can of worms:) I think in Drummonds proposal + and $ also get to have XRD. In the first segment the only place those
symbols formerly known as GCS would have
there conventional meaning is if they are attached to the
first sub segment. If they are the leading character of any other subsegment they would be
treated as * and the =, +, $ are only inferences to the global
concept. Remember I am the one opposed to the change unless there is a good
reason. So take any pro things I say with a grain of salt. The thing is that under that they will be treated as sub segments by
the authority server, so what gets passed? For =drummond@microsoft.com
the first subsegment is =drummond what is the second that get passed to
=drummonds's authority service? @microsoft.com *(@microsoft.com) microsoft.com So would =drummond*microsoft.com produce the same XRD as =drummond@microsoft.com? Could go ether way depending on how we define resolution. Yes having =drummond+phone have its own XRD seems sort of funky to me
as well. John B. On 24-Nov-08, at 10:23 AM, Victor Grey wrote: The confusion with email
addresses, social, technical or otherwise, is not the only problematic aspect
of the @ GCS character. |
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