RE: [xri] Formal proposal on non-resolvable XRIs

["Marc LeMaitre" <marc.lemaitre@onename.com>]

Since I was the one who proposed the original need for a way to
recognize that XRIs convey that they refer to non resolvable resources I
will have a stab at commenting on this....
 
Is it possible for an XRI to include a reference to a resource that is
unresolvable without the XRI itself being unresolvable?  Put another
way; can I have an XRI resolve to a network resource if part of the XRI
references (or cross references) a non resolvable resource. If not then
it seems to me that we just need to notate the entire XRI as
unresolvable. If YES then the non-resolution syntax should be appended
to each segment of the XRI so that it becomes obvious which segments
resolve.
 
An example of the motivation for this would be if an XRI was used to
identify an XML Schema using an XML namespace that included the
authority responsible for creating the schema but that the segment that
identified the schema did not resolve to a copy of the schema on a
network.
 
Does this make sense?
 
marc
 
-----Original Message-----
From: Wachob, Gabe [mailto:gwachob@visa.com] 
Sent: Friday, July 18, 2003 3:29 PM
To: Drummond Reed; xri@lists.oasis-open.org
Subject: RE: [xri] Formal proposal on non-resolvable XRIs
 
Hi all-
         Back in town last night, and I have some comments/questions on
this.

1) Does nonresolvability only apply to an entire XRI or to a part? We
have syntactic constructs that end up applying to the whole XRI value
(e.g. global community  identifiers) and syntactic constructs that only
apply to "parts" (e.g. : or .). Its not clear to me that a global
community identifier is appropriately used here, when perhaps we need
something parallel to the '.' and ':' characters
2) Use of the double $$ is ugly and subject to errors. 
3) Is the use case for this feature to "comment" xri values? If so, then
$$ is definitely ugly. We've got a lot of fancy examples, but perhaps
there's a more obvious answer if we focus on exactly what the issue we
are addressing is.
Sorry for the late replies, but I made a conscious effort to make this a
real vacation (which didn't last NEARLY long enough). 
    -Gabe
 
 

> -----Original Message-----
> From: Drummond Reed [mailto:drummond.reed@onename.com
<mailto:drummond.reed@onename.com> ]
> Sent: Friday, July 18, 2003 10:01 AM
> To: xri@lists.oasis-open.org
> Subject: RE: [xri] Formal proposal on non-resolvable XRIs
>
>
> Based on some off-list feedback that using "$" by itself to indicate
> non-resolvability could be confusing because it overloads the
> meaning of
> $ (esp. because everything else in the $ space uses at least one char
> after the $), I'm modifying my proposal.
>
> The modified proposal is to use "$$" for non-resolvability, i.e., that
> the char following the $ authority char to indicate that "the
> following
> XRI value is non-resolvable" is a second $.
>
> The same equivalence rule applies, i.e., the XRI value
> following "$$" is
> equivalent to the same XRI value without the $$ prefix.
>
> Examples:
>
>         xri:$$/(@foo.bar/baz)            (is equivalent to
> "xri:@foo.bar/baz")
>         xri:$$/(//www.example.com/:1234:56/:78)
>         xri:$$/(urn:isbn:some-isbn-number)
>         xri:@foo.bar/($$/(//www.example.com/:1234:56/:78))
>
> Again, if there are any objections/counterproposals, please
> respond ASAP
> as this is being written into the 07 draft as we speak.
>
> =Drummond
>
>
> -----Original Message-----
> From: Drummond Reed
> Sent: Monday, July 14, 2003 8:34 PM
> To: xri@lists.oasis-open.org
> Subject: [xri] Formal proposal on non-resolvable XRIs
>
> Having noodled over last week's discussions, here's a formal
> proposal to
> close the non-resolvability issues in the 07 draft.
>
> The proposal is that we drop the the use of the "!" character as the
> indicator for non-resolvability, and also drop this as an XRI reserved
> character. (This brings the delta between the URI reserved
> character set
> and the XRI reserved character set down to four chars - left paren,
> right paren, dot, and star.) This also eliminates the issues
> around the
> "!" character not falling cleanly into the 2396 URI component buckets.
>
> In place of "!", we define "$/" as the special metadata that
> identicates
> "the following XRI value is non-resolvable in the context of
> this XRI".
>
> Like any XRI identifier space, if the XRI value following
> "$/" is global
> (rather than local), it must be enclosed as an xref.
>
> Lastly, we specify that the $/ is ignored for purposes of establishing
> equivalence between two XRI values.
>
> Examples:
>
>         xri:$/(@foo.bar/baz)            (is equivalent to
> "xri:@foo.bar/baz")
>         xri:$/(//www.example.com/:1234:56/:78)
>         xri:$/(urn:isbn:some-isbn-number)
>         xri:@foo.bar/($/(//www.example.com/:1234:56/:78))
>
> Note that the last example is (IMO) redundant and not recommended
> because nested xrefs should always be treated as opaque in the context
> of the enclosing XRI. Although they may be resolvable *on
> their own*, in
> the context of the enclosing XRI they are only used to establish a
> shared identifier.
>
> "$/" is proposed because a) it's short, and b) it seems like a logical
> meaning for the standalone meaning of this character, because the $
> space is intended for identifier metadata that will, as a rule, not be
> resolvable, but can only be interpreted in the context of the XRI
> specification.
>
> Please post any problems/counter-proposals by Thursday or
> we'll go with
> this in the 07 draft.
>
> =Drummond
>
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