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Subject: RE: [xri] Updated 2.1 ABNF and global subsegments
Hi All,
Even though Drummond and I discuss his newer proposal
and explore how to make it "work", I'm not promoting it. I still favor the
earlier notion of compact syntax. We never fully got compact syntax to work, but
I think we were close. I think that by limiting the scope of compact syntax to a
single subsegment, lots of the problems would go away. I acknowledge that the
compact syntax would only work for very simple xrefs, but that was its
original intent, and I kinda like that intent.
I don't like the idea of trying to get rid of parens
wherever we can, because even though they make an XRI longer, for more complex
XRIs they help me understand the intent of the XRI - I actually think complex
XRIs that include parens are more legible than ones that
don't.
Regarding the question if "=$d*2006-02-17*(=example)"
and
"=($d*2006-02-17)*(=example)" mean the same thing, I agree that if they normalize to the same value they MUST
represent the same resource. However, these examples just illustrate that we
never completed the normalization rules and syntax. If we define the scope of
compact syntax to be a single subsegment, then these two XRIs are definately not
equivalent (although of course they may be
synonyms).
I do like the idea that bang would no longer be a GCS.
As a matter of fact, I'd like for bang to continue to evolve to the point that
it is just an XRI minter's claim of persistence, and have noting to do with
namespace. I'd like for two XRIs that differ only in bangs to be
considered equivalent for comparison and resolution. Admittedly this idea is not
fully baked.
Marty.Schleiff@boeing.com;
CISSP From: Drummond Reed [mailto:drummond.reed@cordance.net] Sent: Wednesday, March 07, 2007 1:37 PM To: 'Chasen, Les'; xri@lists.oasis-open.org Subject: RE: [xri] Updated 2.1 ABNF and global subsegments Good points/questions,
Les. See [=Drummond] inline. From: Chasen,
Les [mailto:les.chasen@neustar.biz] A couple of
note/comments: * another change that
this includes but does not spell out is that ! is no longer a GCS
character. [=Drummond] Good point.
Standard Example #10 on http://wiki.oasis-open.org/xri/XriCd02/GlobalSubsegments
shows what happens under this proposal – the former ! GCS character (which by
the XRI 2.0 ABNF had to be followed by a second !, so effectively it was always
!!) is now a subspace under another GCS character. For example, the XDI.org !!
registry would become a subspace of the @ registry, i.e., !!1000 would become
@!!1000. * One thing that
confuses me is that the second instance of a global-subseg is a xref without
parenthesis but is not called a xref. [=Drummond] That’s a
good point that was also brought up by Laurie and Marty on our XRI $ Dictionary
calls. It’s purely a semantic issue, but an important one. I went back and
studied the v3 proposal ABNF closely, and I came up with a solution I really
like: remove the usage of “xref” altogether. See my next message to the list
with a full explanation of the v4 I just posted at http://wiki.oasis-open.org/xri/XriCd02/XriAbnf2dot1.
* In this example
=$d*2006-02-17=example how does that compare
to =($d*2006-02-17=example) and
=($d*2006-02-17)=example and
=$d*2006-02-17(=example) and
=($d*2006-02-17)(=example). Do these
all mean the same thing? [=Drummond] Marty and I
went over this same question on our XRI $ Dictionary call yesterday. The first
thing I need to point out is that, although we discussed not needing a delimiter
before parentheses in the 2.1 ABNF, for good reasons Marty and I discovered, we
do need to require one (either a GCS or LCS character). So the last two XRIs in
your question should be =$d*2006-02-17*(=example) and
=($d*2006-02-17)*(=example). [=Drummond] On the
question of whether they all “mean the same thing”, there are two possible
answers: a) yes, they represent the same resource because they *normalize to the same XRI*, or b) they
MIGHT represent the same resource (i.e., be synonyms), but that can only be
determined via resolution. [=Drummond] For good
reasons which we’ll talk about on tomorrow’s call, right now my answer would be
the latter. But I plan to discuss this with Marty further before then (and if we
come to solid conclusion, we’ll post it). =Drummond
From: Drummond
Reed [mailto:drummond.reed@cordance.net] XRI TC Members and
Observers: An update to the proposed ABNF for
XRI Syntax 2.1 has been posted to the XRI TC wiki
at:
http://wiki.oasis-open.org/xri/XriCd02/XriAbnf2dot1 This third draft incorporates
feedback and suggestions from earlier drafts. In particular it now breaks the
former xri-subseg (XRI subsegment) rule into two forms: global-subseg (global
subsegment) and local-subseg (local subsegment). Global subsegments replace the
former compact syntax proposal. A full explanation of global subsegments and how
they would be treated by XRI resolution has been posted
at:
http://wiki.oasis-open.org/xri/XriCd02/GlobalSubsegments Note that the latter page still has
a few TO-DOs at the end which I’ll fill in tomorrow. But I urge you to review
both the proposed ABNF and the global subsegment proposal in preparation for
this Thursday’s call. Also, in a call I had with Les and
Wil and Trung today, Wil took the action item to review the ABNF from the
standpoint of the OpenXRI parser implementation. So he may come back with
suggestions about how rule names might be refactored to best support
implementation. Please do send any feedback/comments
directly to the list, as this is the last major outstanding issue for XRI Syntax
2.1, so we want to close on this and begin drafting as soon as we can to be
ready for final review at the OASIS Symposium starting April
16. =Drummond
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