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Subject: RE: [xri] RE: GCS chars and star in XRI authority resolution
While the ABNF is nominally simpler using the production below, it makes XRIs less regular and harder to understand from a human perspective. If we allow "@!", I belive that we need a very strong reason not to also allow "@*". Mike > -----Original Message----- > From: Drummond Reed [mailto:drummond.reed@cordance.net] > Sent: Monday, August 23, 2004 5:56 PM > To: Lindelsee, Mike ; xri@lists.oasis-open.org > Subject: RE: [xri] RE: GCS chars and star in XRI authority resolution > > > In retrospect I believe we erred in the 1.0 BNF in allowing > what was then > dot (and is now star) after a GCS character. I believe a > cleaner approach in > XRI 1.1 would be the following rationale: > > 1) All the GCS chars except "!" are "proxies" for "*", in > that they default > to a reassignable subsegment. > > 2) Therefore, there is no need for * following a GCS character. It is > redundant - the equivalent of "**", which makes no sense. > > 3) Therefore the simplest rule, which eliminates any confusion and any > chance of false negatives in a equivalence comparision, is > > GCS-authority = gcs-char [ "!" ] [ nz-segment ] > > Also, to keep XRI resolution consistent, the GCS char would be treated > exactly the same as star in subsegment resolution, i.e., it would be > submitted as part of the string being resolved when resolving > against a GCS > root. For example, when resolving "@foo*bar", the string > submitted to the > "@" authority would be "@foo", and the string submitted to the "@foo" > authority would be "*bar". > > =Drummond > > > -----Original Message----- > From: Lindelsee, Mike [mailto:mlindels@visa.com] > Sent: Monday, August 23, 2004 3:57 PM > To: xri@lists.oasis-open.org > Subject: [xri] RE: GCS chars and star in XRI authority resolution > > My preference would be to stick to a completely regular syntax. I.e., > always prefix the sub-segment that follows the GCS char with > a "*" or a "!", > but I realize that this won't be satisfactory for many > others, so I think we > should stick with xri 1.0 rules/syntax wrt this issue and > allow any of: > > xri:@foo > xri:@!foo > xri:@*foo > > where xri:@foo is equivalent to xri:@*foo. > > Mike > > > -----Original Message----- > > From: Drummond Reed [mailto:drummond.reed@cordance.net] > > Sent: Friday, August 20, 2004 3:15 PM > > To: Lindelsee, Mike ; xri@lists.oasis-open.org > > Subject: GCS chars and star in XRI authority resolution > > > > > > Per the question Mike raises: "The inclusion (or not) of the > > delimiter that > > indicates reassignability or persistence in the sub-segment > that gets > > resolved is something that we'll still need to discuss as we revisit > > resolution for 1.1." > > > > I'd like to propose something I think will make both > > equivalence and XRI > > authority resolution simpler in 1.1. > > > > Per the BNF I just posted following Dave's suggestion, a GCS-rooted > > authority segment would be: > > > > GCS-authority = gcs-char [ "!" / "*" ] [ nz-segment ] > > > > Therefore a GCS char can be followed by either an nz-segment, > > or !, or *. So > > the following are all legal: > > > > @foo > > @*foo > > @!foo > > > > In XRI 1.0 we treated "@foo" and "@*foo" as equivalent. We > > said the * was > > "assumed" with any GCS char. > > > > In XRI 1.1 I'd propose that we simplify things in one of two ways: > > > > OPTION 1: BY NOT DEFINING GCS-CHAR AND GCS-CHAR* AS EQUIVALENT > > > > Instead, the rules would be that: > > > > 1) By default, the nz-segment following a GCS char is reassignable. > > 2) In XRI authority resolution, if EITHER ! or * preceed an > > nz-sub-segment, > > they are treated as part of the nz-sub-segment from the > standpoint of > > resolution, i.e., are part of the value being resolved. > > > > By these rules, @foo, @*foo, and @!foo are all different > > values. "foo" is a > > reassignable sub-segment in both "@foo" and "@*foo" by > definition, but > > "@foo" and "@*foo" are not equivalent. > > > > OPTION 2: BY NOT ALLOWING * DIRECTLY AFTER A GCS CHAR > > > > In ths option, the BNF would be: > > > > GCS-authority = gcs-char [ "!" ] [ nz-segment ] > > > > Again, the same two rules proposed in Option 1 would apply. > > Only now you can > > just have "@foo" and "@!foo", because "@*foo" is illegal. > > > > I believe this is actually the option most consistent with > > the rule that by > > default, the nz-sub-segment following a GCS char is > > reassignable, because it > > means that the * is already inherent in the GCS char, just > > the way it is > > inherent in a slash (reassignable sub-segment being the > default after > > slash). > > > > Which do folks prefer? > > > > =Drummond > > > > > > -----Original Message----- > > From: Lindelsee, Mike [mailto:mlindels@visa.com] > > Sent: Friday, August 20, 2004 2:10 PM > > To: xri@lists.oasis-open.org > > Subject: RE: RE: [xri] Initial proposed XRI 1.1 ABNF and > > issues analysis > > > > Bill, > > > > I'm not clear which XRI ABNF you are asking your questions > > with respect to. > > I don't believe that the XRI below (xri:@example*:23:45) > > would be valid > > using XRI 1.0 syntax ('*' is only allowed as a GCS character > > in 1.0). The > > XRI also wouldn't be valid in the original 1.1 ABNF ('*' > and ':' can't > > follow one another). It would be valid in the various > > iterations of the ABNF > > that Dave, Drummond and I have been discussing on the list -- > > though the > > interpretation of the sub-segments might be slightly > > different between the > > various iterations. > > > > The latest proposal would break the XRI up as follows: > > > > 1: @ > > 2: *example (reassignable sub-segment - and showing > > implicit delimiter) > > 3: *:23:45 (reassignable sub-segment) > > > > The inclusion (or not) of the delimiter that indicates > > reassignability or > > persistence in the sub-segment that gets resolved is > > something that we'll > > still need to discuss as we revisit resolution for 1.1. > > > > Mike > > > > > -----Original Message----- > > > From: Barnhill William [mailto:barnhill_william@bah.com] > > > Sent: Friday, August 20, 2004 11:03 AM > > > To: Lindelsee, Mike > > > Cc: xri@lists.oasis-open.org > > > Subject: Re: RE: [xri] Initial proposed XRI 1.1 ABNF and > > > issues analysis > > > > > > > > > Looks good to me as well, but some questions... > > > (1) Is this XRI valid? xri:@example*:23:45 > > > (2) If valid, would it represent 4 resolution steps: > > > 1: @ > > > 2: .example > > > 3: *:23 > > > 4: *:45 > > > With the '. on 1: and the '*' on 4 being implicitly stated. > > > > > > (3) If the above XRI is suppose to respresent 4 resolution > > > steps do not > > > the new rules result in only 3 steps? As :23:45 would be > > > considered one > > > segment. > > > > > > Thanks, > > > > > > Bill Barnhill > > > > > > > > > > > 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 > the roster of the OASIS TC), go to > http://www.oasis-open.org/apps/org/workgroup/xri/members/leave > _workgroup.php. > >
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