Re: [urn] Preferences and Choice matrix
John C Klensin <john-ietf@jck.com> Sun, 03 August 2014 19:21 UTC
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Date: Sun, 03 Aug 2014 15:20:52 -0400
From: John C Klensin <john-ietf@jck.com>
To: Keith Moore <moore@network-heretics.com>, "Leslie Daigle (TCE)" <ldaigle@thinkingcat.com>, urn@ietf.org
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Subject: Re: [urn] Preferences and Choice matrix
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--On Monday, 28 July, 2014 06:13 -0400 Keith Moore <moore@network-heretics.com> wrote: > On 07/27/2014 03:35 AM, "Martin J. Dürst" wrote: >> I actually think it's utterly consistent with RFC 3986. RFC >> 3986 only says that it's "scheme definable". This means that >> a scheme can define what it wants. >> > Yes, 3986 allows a scheme to define what it wants. The > reason that "?" should not have a namespace-specific meaning > is not because 3986 prohibits it. > > Some reasons that "?" should not have a namespace-specific > meaning are: >... Can I encourage you to be a little bit more specific about what you are talking about and specifically what you mean by "meaning"? For example, I don't have much problem with saying "ok, there are things that, for lack of a better term, we will call 'queries'. From the standpoint of syntax the query collection starts with "?" and continues to the end of the URI string or the first occurrence of '#'. After that, their interpretation is pretty much an NID problem". Up to the last sentence that is, I think, pretty much what 3986 says. The last sentence is problematic is one believes that 3986 makes query interpretation a per-scheme problem that can't be delegated to NID registrations. That interpretation is more than sufficient to make generic URI parsers, and even more specific generic URN parsers feasible. Where things get complicated is when wants to specify syntax or interpretation/semantics _within_ the query string. I can see doing that for at least one more layer on an "all-URNs" basis, but believe we would have to be very careful about extensibility. Proposals to create a closed list of keywords with "all-URN" interpretations scare me because I don't think we can get that right in a single attempt. But, if one can specify that on a per-NID basis, I don't see any problem even though I personally think it would be desirable to push a level further down (see below). Similarly, in a world of generalized URNs, I think one needs to be very careful about rules about what is included in URN equality or about the context in which something is evaluated. If those things are specified for all URNs (or all URIs), then I think we are likely to get into trouble given some of the examples Juha, Lars, and others have given. On the other hand, if they are pushed down to the NID level, then the registry (or some information without the query string itself) has to be consulted before performing those interpretations. That isn't impossible, but it would certainly be inconvenient for many purposes (that statement is intended to be consistent with Leslie's "not only tricky, it's likely to lead to heartbreak", which which I agree. One could pretty much substitute "fragment/ #" or "/" with some appropriate words for "query / ?" above without changing much, if anything. --On Wednesday, 30 July, 2014 11:11 -0400 "Leslie Daigle (TCE)" <ldaigle@thinkingcat.com> wrote: (paragraphs rearranged for my convenience) > Thumbwrestling about interpretations of RFC3986 is distracting > from the hard problem, IMO. Agreed. See my prior note about the new version of the separation draft. In retrospect, the Toronto meeting was disappointing because we ended up spending almost all of our time on that issue and hence couldn't get to the ones that you and Keith are now raising. > Getting beyond the meta, I'd like to see actual proposals for > how to handle facets (whether using the "?" and "#" or not) in > a way that works consistently across all persistent > identifiers. > I don't have a proposal to kick off the discussion, as I am a > self-admitted skeptic :-) Various of us have tried to identify types of URNs and, in some cases, the differences among their requirements. At other times, we have tried to predict the future, both in terms of requirements and in terms of whether new types will be discovered. Against that background, the only thing I know how to propose is fully general, e.g., the four-tuple Service Request described in Appendix B of draft-ietf-urnbis-urns-are-not-uris-01 and some earlier notes. I hope we can be less general than that, but I'm not convinced yet, especially if strong equality comparisons for URNs (high on the "fewer false negatives" ladder but without relying on comparison of retrieved content are desired. It would, FWIW, be completely rational to use "?" to introduce service requests that are interpreted "outside" the URN and URN comparisons and "/" for ones that are interpreted "inside" the URN and that count in comparisons if that distinction were sufficient. If it were and we went down that path, the four-tuple would drop to a three-tuple. However, to remove some of the noise from that discussion, I suggest it would be useful to concentrate on what we want those Service Requests to be able to do, specify, and how and where they are interpreted, rather than on their syntax. > To further remove noise from that discussion, I think having > the discussion in the abstract -- e.g., for a new > [UR]identifier, as Joe Hildebrand suggested at the meeting > last week -- might be helpful. Works for me with one qualification, which is almost the same qualification I would apply to "use '/' and not '?'". I believe we are stretching the patience of those who have been waiting for us to bring this work to a useful and usable conclusion but who have been assigning and using millions of URNs in the meantime. The result of pushing them too far is fairly clear -- we end up with a forked standard published by a group that has far more credibility in parts of the URN-using community than the IETF does. Except that most of that community it far too polite, I think the effect of any "don't use URNs, use URXs or XXNs instead and you can start converting your millions of URNs now" would be a lot of rude language and precisely that form. Put differently, if thinking about this as a new URI type helps us move things forward, that is fine, but an actual proposal that URNs, or URNs beyond what 2141 allows, be actually replaced by such a type, would be likely to be ignored in the marketplace (or worse). john
- Re: [urn] Choice matrix John C Klensin
- [urn] Choice matrix Leslie Daigle (TCE)
- Re: [urn] Choice matrix Julian Reschke
- Re: [urn] Choice matrix Leslie Daigle (TCE)
- Re: [urn] Choice matrix Svensson, Lars
- Re: [urn] Choice matrix Julian Reschke
- Re: [urn] Choice matrix Leslie Daigle (TCE)
- Re: [urn] Choice matrix John C Klensin
- Re: [urn] Choice matrix Julian Reschke
- Re: [urn] Choice matrix Leslie Daigle (TCE)
- Re: [urn] Choice matrix John C Klensin
- Re: [urn] Choice matrix Julian Reschke
- Re: [urn] Choice matrix Julian Reschke
- Re: [urn] Choice matrix John C Klensin
- Re: [urn] Choice matrix Svensson, Lars
- Re: [urn] Choice matrix Julian Reschke
- Re: [urn] Choice matrix Martin J. Dürst
- Re: [urn] Choice matrix Martin J. Dürst
- Re: [urn] Choice matrix Martin J. Dürst
- Re: [urn] Choice matrix Martin J. Dürst
- Re: [urn] Choice matrix Keith Moore
- Re: [urn] Choice matrix Keith Moore
- Re: [urn] Choice matrix Leslie Daigle (TCE)
- [urn] PReferences (no longer really Re: Choice ma… Leslie Daigle (TCE)
- Re: [urn] PReferences (no longer really Re: Choic… Keith Moore
- Re: [urn] Preferences and Choice matrix John C Klensin