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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 >
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