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Subject: RE: [xri] A different perspective on * and / (long)


Can you also talk about how this would affect resolution of relative
references, which currently depends on an unambiguous hierarchical
structure based on slash?

Dave

> -----Original Message-----
> From: Wachob, Gabe [mailto:gwachob@visa.com]
> Sent: Monday, June 14, 2004 9:46 AM
> To: Drummond Reed; xri@lists.oasis-open.org
> Subject: RE: [xri] A different perspective on * and / (long)
> 
> I hadn't realized this was the proposal.
> 
> How would this affect XRI resolution? What marks the end of the ID
> Authority? If the two delimiters are *truly* equal, then it would seem
> that the first of either of them would mark the end of the authority,
but
> that means that * couldn't be used as an authority delegation
character.
> 
> If the "/" still marks the end of the authority, then it seems a
little
> odd since we're basically saying the two delimiters really aren't
> equivalent.
> 
> Explain please ;-)
> 
> 	-Gabe
> 
> 
> __________________________________________________
> gwachob@visa.com
> Chief Systems Architect
> Technology Strategies and Standards
> Visa International
> Phone: +1.650.432.3696   Fax: +1.650.554.6817
> 
> 
> > -----Original Message-----
> > From: Drummond Reed [mailto:drummond.reed@cordance.net]
> > Sent: Sunday, June 13, 2004 11:22 PM
> > To: xri@lists.oasis-open.org
> > Subject: RE: [xri] A different perspective on * and / (long)
> >
> >
> > That's a good one, Gabe - "failing to connect the dots" ;-)
> >
> > Anyway, to answer your question, the impact on the BNF is
> > that star would
> > now have an equal footing with slash. Either could be used to
> > delimit a
> > "segment", and either could be followed by a colon to denote
> > a persistent
> > segment (with the absence of a colon as the first character
> > of the segment
> > meaning the segment is reassignable).
> >
> > This is a significant simplification because "subsegments" go
> > away. Now
> > there would be just star segments and slash segments and they
> > would both
> > behave identically. The xri-segments production would become:
> >
> > xri-segments = [ ":" ] segment-value *( ( "/" / "*" ) [":"]
> > segment-value )
> > segment-value  = 1*xri-pchar / xref
> >
> > =Drummond
> >
> > -----Original Message-----
> > From: Wachob, Gabe [mailto:gwachob@visa.com]
> > Sent: Friday, June 11, 2004 10:19 AM
> > To: Drummond Reed; xri@lists.oasis-open.org
> > Subject: RE: [xri] A different perspective on * and / (long)
> >
> > Drummond-
> > 	Somewhere along the line, I'm failing to connect the
> > dots. While I
> > understand the idea that peer-links should be representable
> > in XRIs, and I
> > understand your proposal of using syntax to do this, I'm not
> > understanding
> > how this impacts the */: vs. *:/*. discussion..
> >
> > 	-Gabe (who never admits to things he thinks about at 4am ;-)
> >
> >
> > __________________________________________________
> > gwachob@visa.com
> > Chief Systems Architect
> > Technology Strategies and Standards
> > Visa International
> > Phone: +1.650.432.3696   Fax: +1.650.554.6817
> >
> >
> > > -----Original Message-----
> > > From: Drummond Reed [mailto:drummond.reed@cordance.net]
> > > Sent: Friday, June 11, 2004 9:10 AM
> > > To: xri@lists.oasis-open.org
> > > Subject: [xri] A different perspective on * and / (long)
> > >
> > >
> > > I realize I am in the minority in the perspective I'm sharing
> > > on the * vs. :
> > > issue. In the message below Peter adds his vote along with
> > Gabe, Mike,
> > > Loren, and Dave to the preference to use both * and : as
> > "second-level
> > > hierarchy characters", whereas I am advocating using just *.
> > >
> > > However after a conversation Dave and I had about this late
> > > yesterday, I
> > > woke up thinking about it at 4am this morning and came to a
> > > much deeper
> > > understanding of why there appears to be such a huge gap
> > > between these two
> > > perspectives. Since I couldn't get back to sleep, I'll try to
> > > explain it
> > > here.
> > >
> > > First, just to make it clear, I agree with everyone that if
> > > the choice is
> > > simply between the "readability" of the two examples given
> > > below, i.e.:
> > >
> > > xri:@:3*:4*:5/:6*:7
> > > or
> > > xri:@:3:4:5/:6:7
> > >
> > > ...then of course it appears to be a no-brainer. The latter
> > > is more compact
> > > and, as Peter says, "much easier to read".
> > >
> > > But therein lies the issue. What is "easier to read" depends
> > > on what you are
> > > reading for. What I realized laying in bed at 4am this
> > > morning is that I am
> > > reading for something entirely different. But to explain
> > this requires
> > > explaining the entire worldview behind this perspective, and
entire
> > > worldviews are not easy to explain, so please bear with me
> > > while I try.
> > >
> > > In this second worldview, * would not be considered a
> > > "secondary hierarchy
> > > character", but an "alternative hierarchy character" on an
> > > equal footing
> > > with slash.
> > >
> > > I can just hear Dave screaming right now, "What does Drummond
> > > mean, 'an
> > > "alternative hierarchy character" on an equal footing with
> > > slash'?? How
> > > could there be such a thing? Slash is THE 2396 hierarchy
> > character! It
> > > defines 2396 segments. The only option we have is to define
> > > subsegments
> > > within slash segments!"
> > >
> > > But this is exactly what I mean about two entirely different
> > > worldviews. In
> > > the 2396 worldview the world is purely hierarchical. There is
> > > only slash
> > > because there is only hierarchy.
> > >
> > > It's pretty ironic, then, that URIs based on 2396 are the
> > > very basis of the
> > > World Wide Web, which is the very opposite of hierarchy. It's
> > > a peer-to-peer
> > > web. Any page can link to any page.
> > >
> > > Laying in bed at 4am, I did the following thought experiment,
"Using
> > > conventional URIs, is there any way you can address the LINK
> > > between two web
> > > pages?" In other words, not the URI of Page A or the URI of
> > > Page B, but the
> > > LINK from Page A to Page B. Literally, the A tag present in
> > > the HTML of Page
> > > A that links to Page B.
> > >
> > > There is certainly no standard way, at least that I know of.
> > > So I started
> > > thinking through how you would do it. If Page A was expressed
> > > as XHTML, then
> > > the actual node of the XHTML document that contains the link
> > > to Page B would
> > > at least be addressable using an XPath expression under the
> > > URI of Page A.
> > > So you could have something like:
> > >
> > > http://www.example.com/Page-A#Xpath-to-A-tag-linking-Page-B
> > >
> > > Of course, there is no spec for doing this that I am aware
> > > of. However it
> > > wouldn't be hard to construct one. Since you know the link is
> > > in an A tag,
> > > you'd just need a standard XPath query that says, "Give me
> > > the A tag whose
> > > HREF attribute equals the following value" and then supply
> > > the target URI as
> > > a paremeter. Say this query was called "Xpath-A-ref". Then
> > > any site that
> > > supported this query could resolve a URI that looked like the
> > > following:
> > >
> > > http://www.example.com/Page-A?Xpath-A-ref&HREF="http://www.sit
> > > e.com/Page-B"
> > >
> > > Such an address would actually let you address Page B in the
> > > context of Page
> > > A. It lets you construct a path ACROSS pages, not just DOWN
> > > the DNS tree and
> > > local file path hierarchy to a specific page.
> > >
> > > Why would you want to be able to address across Web pages? If
> > > you wanted to
> > > be able to follow the path of who is linked to who. It lets you
test
> > > assertions about relationships between pages. If the address
> > > above resolves,
> > > it tells you Page A is linked to Page B. If it doesn't, they
aren't.
> > >
> > > Now, imagine if there was: a) a standard URI syntax character
> > > that equates
> > > to the link query operation "?x-path-A-ref" above, and b) a
> > > standard way in
> > > URI syntax to nest one URI inside another. Let's say the
> > > standard link query
> > > character was * and the nesting syntax was to enclose the
> > > nested URI in
> > > parentheses. Then the URI above could be expressed much more
> > > compactly and
> > > readably as:
> > >
> > > 	http://www.example.com/Page-A*(http://www.site.com/Page-B)
> > >
> > > Now let's take one more step. Say that the author of Page A
> > > had his own name
> > > for Page B inside the HREF tag that points to
> > > "http://www.site.com/Page-B";.
> > > Say this name was "Glockenspiel". This is really a relative
> > > identifier for
> > > Page B, since it's relative to the Web page
> > > http://www.example.com/Page-A.
> > > But in the context of this Web page, it's very likely to be
> > > unique, since
> > > the author of Page A is unlikely to create two outgoing links
> > > to different
> > > resources on the same Web page and label both the A tags
> > identically.
> > >
> > > In this case there is a second way to address the link
> > > between Page A and
> > > Page B using this relative identifier. This would look like:
> > >
> > > 	http://www.example.com/Page-A*(Glockenspiel)
> > >
> > > I know this example has been quite extensive, but as you can
> > > see, the point
> > > is that in this alternative worldview - this Web-based worldview -
> > > peer-to-peer linking relationships have an equal status with
> > > hierarchical
> > > relationships. Neither is "good" or "bad". Neither is "primary" or
> > > "secondary". They are simply equally valid. Like Cartesian
> > and radian
> > > coordinate systems, they both let you address any point on a
> > > plane - it's
> > > just that each one can be much more appropriate for certain tasks.
> > >
> > > It follows then that in this worldview, the primary failing
> > > of 2396 syntax
> > > is that it does not accommodate the peer-to-peer linking
> > > worldview. It only
> > > accommodates the hierarchical worldview. It has no syntax for
> > > addressing
> > > link relationships, nor for nesting identifiers for this
> > > purpose (i.e.,
> > > cross-references). In syntactic terms, it has only /, and
> > no * nor ().
> > >
> > > Those of you who know me know why I am so passionate about
> > > this subject. To
> > > get from the Web to the Dataweb, we must be able to express
> > the links
> > > between data and the links between data sharing authorities.
> > > Suddenly it is
> > > as important (if not more important) to be able to address
> > > the source of
> > > authority and permission in a data sharing relationship as it
> > > is to be able
> > > to address the data being shared.
> > >
> > > For example, look at the following sample XRI:
> > >
> > > xri:xri-A/(xri-B)*(/($contract)/this-contract/($v1))*(/(+email
> > > )/work/($v2))
> > >
> > > (Note that the values "xri-A" and "xri-B" are placeholders
> > > for the actual
> > > XRIs for Authority A and Authority B, and "$contract" is the
> > > proposed XRI
> > > service dictionary identifier for XDI link contracts.) This
> > > is from a thread
> > > about potential XDI contract addressing available at
> > > http://wiki.idcommons.net/moin.cgi/DataSharing#head-0bd5430345
> > > 33c5641c0beacf
> > > 65be418a7a9c7fc5.
> > >
> > > Although this particular example is in the context of XDI
> > > (and uses only a
> > > proposed addressing syntax in that context), what I believe
> > > it illustrates
> > > is the tremendous importance, in that context, of link
> > > relationships. For
> > > example, this XRI expresses that authority A's relationship
> > > with authority B
> > > (xri-A/xri-B) is linked to a link contract from authority A
> > > (/($contract)/this-contract/($v1)) which is linked to a
> > > specific item of
> > > data from authority A (/(+email)/work/($v2)).
> > >
> > > So, in conclusion:
> > >
> > > * In the hierarchical-only worldview, / reigns supreme, and
> > > therefore the
> > > distinction between * and : as "secondary hierarchy"
> > > characters appears
> > > relatively minor.
> > >
> > > * In the combined hierarchy-and-peer-to-peer-link worldviews,
> > > / and * are
> > > equally important and equally valid first-level delimiters. /
> > > is used to
> > > express for hierarchical relationships between resources and
> > > * is used to
> > > express peer-to-peer linking relationships between
> > resources. In this
> > > worldview, both "/:" and "*:" would be equally valid, as
> > > colon would always
> > > be used as the prefix for a persistent identifier.
> > >
> > > I believe this worldview is not unique to XDI. Although XDI
> > > architecture is
> > > fundamentally based on the ability to express links between
> > > resources, and
> > > it uses XRIs for this purpose, I believe that establishing
> > > the syntactic
> > > "equal footing" of * and / for the purpose of enabling the
> > > expression of
> > > peer-to-peer linking vs. hierarchical relationships could
> > > apply to many
> > > other uses of XRI beyond the scope of XDI.
> > >
> > > I hope this explanation helps bridge the gap between these
> > > two worldviews.
> > >
> > > =Drummond
> > >
> > > -----Original Message-----
> > > From: Peter C Davis [mailto:peter.davis@neustar.biz]
> > > Sent: Friday, June 11, 2004 5:45 AM
> > > To: Lindelsee, Mike
> > > Cc: xri@lists.oasis-open.org
> > > Subject: RE: [xri] RE: Single delegation character
> > >
> > > ditto.  it is, among other things, much easier to read.
> > >
> > > --- peterd
> > >
> > > On Thu, 2004-06-10 at 17:56, Lindelsee, Mike wrote:
> > > > I also prefer the latter for the same reasons that Dave and
> > > Loren do.
> > > >
> > > > Mike
> > > >
> > > > -----Original Message-----
> > > > From: Dave McAlpin [mailto:Dave.McAlpin@epok.net]
> > > > Sent: Thursday, June 10, 2004 2:26 PM
> > > > To: Loren West; xri@lists.oasis-open.org
> > > > Subject: RE: [xri] RE: Single delegation character
> > > >
> > > >
> > > > Good point. Now that we've beaten the delegation issue to
> > > death, we can
> > > > come back to the original question about whether we should
> > > define one or
> > > > two second level delimiters.
> > > >
> > > > The question is whether we prefer
> > > >
> > > > xri:@:3*:4*:5/*:6*:7
> > > >
> > > > or
> > > >
> > > > xri:@:3:4:5/:6:7
> > > >
> > > > for reasons already stated. My preference is the second,
> > > i.e. to define
> > > > two second level separators, star ("*") and colon (":").
> > > >
> > > > Dave
> > > >
> > >
> > >
> > >
> > >
> > > To unsubscribe from this mailing list (and be removed from
> > > the roster of the OASIS TC), go to
> > > http://www.oasis-open.org/apps/org/workgroup/xri/members/leave
> > > _workgroup.php.
> > >
> >
> >
> >
> > To unsubscribe from this mailing list (and be removed from
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> 
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