Re: [VCARDDAV] updating vCard 3.0 to vCard 4.0
"Javier Godoy" <rjgodoy@fich.unl.edu.ar> Fri, 16 July 2010 10:10 UTC
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From: Javier Godoy <rjgodoy@fich.unl.edu.ar>
To: Daisuke Miyakawa <d.miyakawa@gmail.com>
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Date: Fri, 16 Jul 2010 07:09:30 -0300
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Subject: Re: [VCARDDAV] updating vCard 3.0 to vCard 4.0
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Daisuke Miyakawa wrote: > Interesting. I'd like to have some documentation describing relation between > vCard 3.0 and 4.0, while I don't know there's any draft for it. > As for the mapping from 3.0 to 4.0, however, I have some concerns. > vCard 3.0 just recommends UTF-8. It is not MUST. Actually I've seen some > device emitted vCard with Japanese >local charset called Shift_JIS. >One-to-One mapping from Shift_JIS to UTF-8 is sometimes impossible, as far as >I rember. I didn't know that some Shift-JIS characters cannot be represented in UTF-8, and I couldn't find any reference about that, either. Despite of some ambiguities [1], it seems that Unicode is a superset of Shift-JIS [2]: [[ How is JIS X0213 related to Unicode / ISO/IEC 10646? Almost all characters in JIS X0213 have corresponding characters in Unicode / ISO/IEC 10646. Only a few non-Kanji characters are represented by composite sequences in Unicode / ISO/IEC 10646. Kanji characters are mapped to one of the blocks of CJK Unified Ideographs, CJK Compatibility Ideographs, CJK Unified Ideographs Extension A, or CJK Unified Ideographs Extension B in Unicode 4.0 (or later versions) and corresponding versions of ISO/IEC 10646; or are mapped to CJK Compatibility Ideographs. ]] [1] http://www.w3.org/TR/japanese-xml/#ambiguity_of_yen [2] http://unicode.org/faq/han_cjk.html#8 >There are some other examples I can find which makes the migration difficult. > From the actual usage, I personally want such documentation anyway. > I think we don't need to have a strict mapping but some guideline, though I > agree it won't be a formal "specification". In some cases, the mapping is strict (such as removing separators from date values), but for the general case there are some situations that cannot be solved "by the given algorithm" (for instance, vCard 4.0 does not allow inline entities, which were allowed for the RFC 2426 AGENT property, now subsumed into AGENT; one should a stream of vCards for that purpose, but the nature of this "stream" depends on which context the vCard is used). And there are other cases where several solution exists (should I map TZ as text values, or try heuristics for matching it against Olson database entries?) At least we should call attention to some changes, in order to facilitate the migration. I call this task upon us because we already know what has changed, and (more importantly) we know why we changed it that way. As the WG, we can authoritatively review the guidelines, even though they are not part of the standard. > For example, now we have SORT-AS parameter instead of vCard 3.0's > SORT-STRING, strings for sort should be > composed differently. That is tricky. SORT-STRING represents the national-language-specific sorting of the FN property, while SORT-AS applies to N and other properties, but FN is not among them. The issue is that we had no per-component sorting information in vCard 3.0: FN:Oscar del Pozo N:del Pozo Triscon;Oscar SORT-STRING:Pozo In this example, the preferred vCard 4.0 form would be FN:Oscar del Pozo N;SORT-AS="Pozo;Oscar":del Pozo Triscon;Oscar;; But this mapping is not always straightforward: - SORT-STRING allows LANGUAGE param. SORT-AS assumes the same LANGUAGE as the N property where it occurs. Language matching should be applied. - What would happen if SORT-STRING had x-params? - There was no sorting information for the given-name "Oscar". Should we assume that the given-name from N is the sorting given-name? (in Japanese, that would mean that SORT-AS would contain kanji instead of kana, since N is written in kanji), should it be left empty? - The definition of SORT-STRING is confusing ("the sort string is used to provide family name or given name text that is to be used in sorting", but the examples in RFC 2426 provide SORT-STRINGs where only the family name is given). The example above could have been SORT-STRING:Pozo Triscon Oscar, from which a naive algorithm could derive SORT-AS="Pozo Triscon Oscar;" or SORT-AS="Pozo Triscon Oscar;Oscar". One could try removing the given-name from the SORT-STRING, but the given-name is not guaranteed to be contained verbatim in the SORT-STRING. Best Regards Javier 2010/7/15 Javier Godoy <rjgodoy@fich.unl.edu.ar> ¿Will be there a WG draft about updating from vCard 3.0 to vCard 4.0? I'm concerned that, after the publication of vcardrev, systems supporting vCard 4.0 would have to interoperate with systems supporting vCard 3.0-only. . Besides, since RFC 2425 and RFC 2426 will be obsolete, the requirement of "supporting both vCard 3.0 and vCard 4.0" will imply references to the obsolete and current standards, on an equal footing. Instead, I would like to require "mapping from vCard 3.0 to vCard 4.0", and have such mapping reviewed by the same people who participated in the discussion about vcardrev. Interoperability with older systems may also require exporting vCard 4.0 instances as vCard 3.0. Later, the downgraded instance might be converted back to vCard 4.0. I would like to provide a mechanism for preserving as much information as possible during this mapping. I think the community would benefit and feel more confident if some broadly-discussed guidelines are provided, instead of asking each implementor to reinvent the wheel. If this is not in the schedule, and if you think it might be usefeul, I would like to take this responsability. Best Regards Javier
- [VCARDDAV] updating vCard 3.0 to vCard 4.0 Javier Godoy
- Re: [VCARDDAV] updating vCard 3.0 to vCard 4.0 Daisuke Miyakawa
- Re: [VCARDDAV] updating vCard 3.0 to vCard 4.0 Javier Godoy