- From: David Booth <david@dbooth.org>
- Date: Mon, 29 Dec 2014 13:52:30 -0500
- To: Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk>
- CC: "public-rdf-comments@w3.org" <public-rdf-comments@w3.org>
P.S. Or to put it differently, it would be harmful if anyone interpreted the existing ambiguity to be intentional. On 12/29/2014 01:36 PM, David Booth wrote: > FWIW, it certainly seems to me like this detail was omitted > unintentionally and would be helpful to include in the errata. > > David Booth > > On 12/29/2014 12:50 PM, Stian Soiland-Reyes wrote: >> OK, thank you all for recollecting! So I'll settle for the "naked" >> literal in output of an xsd:string. >> >> Should this go into an errata or is it too much of a change? >> >> On 29 Dec 2014 07:41, "Andy Seaborne" <andy@apache.org >> <mailto:andy@apache.org>> wrote: >> >> On 29/12/14 06:31, Pat Hayes wrote: >> >> >> On Dec 28, 2014, at 6:10 PM, Gregg Kellogg >> <gregg@greggkellogg.com <mailto:gregg@greggkellogg.com>> wrote: >> >> On Dec 28, 2014, at 3:32 PM, Pat Hayes <phayes@ihmc.us >> <mailto:phayes@ihmc.us>> wrote: >> >> >> >> On Dec 28, 2014, at 5:40 AM, Andy Seaborne >> <andy@apache.org <mailto:andy@apache.org>> wrote: >> >> On 28/12/14 05:04, Pat Hayes wrote: >> >> On Dec 27, 2014, at 9:24 PM, Stian >> Soiland-Reyes >> <soiland-reyes@cs.manchester.__ac.uk >> <mailto:soiland-reyes@cs.manchester.ac.uk>> >> wrote: >> >> No, for once I am not coming from OWL :) >> >> I'm just writing a simple n-triples >> serializer, and I am not sure if I should >> simply always include the type if there is >> no @lang (e.g. ^^xsd:string) >> >> >> It was certainly the intention of the RDF 1.1 WG >> that every literal should have a type. We even >> provided a special 'type' for the @lang case, to >> preserve this intention. It seems to me that one >> should not ever go wrong by including the >> ^^xsd:string, which was semantically correct >> even in original RDF, whereas really plain plain >> literals now have the shadow of deprecation >> hanging over them, at the very least. >> >> Hope this helps. >> >> Pat Hayes >> >> >> And for serialization, the WG intention IIRC was >> that all ^^xsd:strings should be written without the >> ^^xsd:string in all formats where possible. >> >> >> Really? I have no recollection of that, but I may have >> missed some discussions. Can you find this in the >> minutes or emails anywhere? >> >> >> I share Andy's recollection >> >> >> OK, two is enough :-) I bow to your superior recollection, and >> withdraw my implicit advice to use explicit xsd:string typing. >> Apologies to all concerned. >> >> >> I went looking (OK, a bit of looking) the first time but couldn't >> find spec text except the MAY. This discussion was over an extended >> period. >> >> The examples for Turtle are without xsd:string (except to show they >> are the same). >> >> >From memory, the line of argument was that simple literals were >> more common than explicit ^^xsd:string though the community of use >> is going to be a major factor. >> >> Like Gregg, Jena outputs without explicit datatype as the best >> choice overall. >> >> Andy >> >> >> Pat >> >> , and that is how my serializer behaves. >> Shame that the spec-text doesn't cspture that. >> >> Gregg >> >> It look nicer. >> >> >> Maybe, but it also can produce uncertainty, as for >> example: >> >> "Before rdf 1.1 the norm tended to be to NOT express >> xsd:string unless it really was a character-by-character >> string (e.g. a genome identifier), and not when it was >> human text (but in unknown or mixed language)." >> >> Even in RDF 1.0, plain literals were specified to be >> semantically identical to xsd:string-typed literals, but >> this was buried in the semantics dociument which nobody >> read, and because the syntactic distinction was >> available, people assumed it meant something. As long as >> a syntax offers both choices, this misreading process >> will continue to operate, even now RDF 1.1 has said >> explicitly that plain literals are only syntactic sugar >> for the typed version. >> >> >> http://www.w3.org/TR/rdf11-__concepts/#section-Graph-__Literal >> >> <http://www.w3.org/TR/rdf11-concepts/#section-Graph-Literal> >> only says "MAY" -- that is mainly so as not to >> suggest much RDF 1.0 data output by pre-existing >> software is suddenly invalidated, which it isn't. >> >> >> Certainly, plain literal surface syntax is not >> *invalidated* by RDF 1.1. Sorry if I gave that >> impression. >> >> Pat >> >> >> >> Andy >> >> >> >> ..Or if I should have a special case to >> output anything with type xsd:string as a >> classic "plain literal", e.g. no @ or ^^. >> >> Surely just one of these should be in the >> canonical version ? My guts says to always >> include the type for non-lang, but the spec >> is ambigous on this - if xsd:string is >> implied, should I then prefer to generate >> this implied version? >> >> Before rdf 1.1 the norm tended to be to NOT >> express xsd:string unless it really was a >> character-by-character string (e.g. a genome >> identifier), and not when it was human text >> (but in unknown or mixed language). >> >> As we SHOULD be generating the Canonical >> N-Triples, then it would be good to know if >> there already is a silent de facto agreement >> that is just not expressed in the spec. >> >> You might know the code base - >> >> https://github.com/stain/__commons-rdf/blob/tests/src/__test/java/com/github/__commonsrdf/dummyimpl/__LiteralImpl.java#L99 >> >> >> <https://github.com/stain/commons-rdf/blob/tests/src/test/java/com/github/commonsrdf/dummyimpl/LiteralImpl.java#L99> >> >> >> On 27 Dec 2014 17:14, "Peter Ansell" >> <ansell.peter@gmail.com >> <mailto:ansell.peter@gmail.com>> wrote: >> Hi Stian, >> >> RDF-1.1 does not have the concept of plain >> literals [1]. Hence, it is >> difficult to map the OWL-WG-derived >> rdf:PlainLiteral set to RDF-1.1, >> if that is where you are coming at the issue >> from [2]. >> >> Cheers, >> >> Peter >> >> [1] >> >> http://www.w3.org/TR/2014/REC-__rdf11-concepts-20140225/#__section-Graph-Literal >> >> >> <http://www.w3.org/TR/2014/REC-rdf11-concepts-20140225/#section-Graph-Literal> >> >> [2] >> https://github.com/owlcs/__owlapi/issues/172 >> <https://github.com/owlcs/owlapi/issues/172> >> >> On 27 December 2014 at 16:37, Stian >> Soiland-Reyes >> <soiland-reyes@cs.manchester.__ac.uk >> <mailto:soiland-reyes@cs.manchester.ac.uk>> >> wrote: >> >> In >> >> http://www.w3.org/TR/n-__triples/#canonical-ntriples >> >> <http://www.w3.org/TR/n-triples/#canonical-ntriples> >> I read: >> >> Canonical N-Triples has the >> following additional constraints on >> layout: >> >> The whitespace following >> subject, predicate, and object MUST >> be a single space, (U+0020). All >> other locations that allow >> whitespace MUST be empty. >> There MUST be no comments. >> HEX MUST use only uppercase >> letters ([A-F]). >> Characters MUST NOT be >> represented by UCHAR. >> Within STRING_LITERAL_QUOTE, >> only the characters U+0022, U+005C, >> U+000A, U+000D are encoded using >> ECHAR. ECHAR MUST NOT be used for >> characters that are allowed directly >> in STRING_LITERAL_QUOTE. >> >> >> >> and in >> >> http://www.w3.org/TR/n-__triples/#sec-parsing-terms >> >> <http://www.w3.org/TR/n-triples/#sec-parsing-terms> >> >> If neither a language tag nor a >> datatype IRI is provided, the >> literal has a datatype of xsd:string. >> >> >> >> and in >> >> http://www.w3.org/TR/n-__triples/#sec-literals >> >> <http://www.w3.org/TR/n-triples/#sec-literals> >> >> If there is no datatype IRI and no >> language tag it is a simple literal >> and the datatype is >> >> http://www.w3.org/2001/__XMLSchema#string >> >> <http://www.w3.org/2001/XMLSchema#string>. >> >> >> Example 3 >> <http://example.org/show/218> >> >> <http://www.w3.org/2000/01/__rdf-schema#label >> >> <http://www.w3.org/2000/01/rdf-schema#label>> >> "That Seventies >> >> Show"^^<http://www.w3.org/__2001/XMLSchema#string >> >> <http://www.w3.org/2001/XMLSchema#string>> >> . # literal with XML Schema string >> datatype >> <http://example.org/show/218> >> >> <http://www.w3.org/2000/01/__rdf-schema#label >> >> <http://www.w3.org/2000/01/rdf-schema#label>> >> "That Seventies Show" . # same as >> above >> >> >> >> So I am not any wiser with regards to >> how to serialize plain literals >> in RDF 1.1 Canoical N-Triples.. >> >> >> Are both of the two examples allowed in >> Canonical N-Triples? (it seems >> so by the spec.. :-( ). >> >> Which variant should I generate? >> >> >> -- >> Stian Soiland-Reyes, myGrid team >> School of Computer Science >> The University of Manchester >> http://soiland-reyes.com/__stian/work/ >> <http://soiland-reyes.com/stian/work/> >> http://orcid.org/0000-0001-__9842-9718 >> <http://orcid.org/0000-0001-9842-9718> >> >> >> >> ------------------------------__------------------------------ >> IHMC >> (850)434 8903 home >> 40 South Alcaniz St. (850)202 4416 >> office >> Pensacola (850)202 >> 4440 fax >> FL 32502 (850)291 >> 0667 mobile (preferred) >> phayes@ihmc.us <mailto:phayes@ihmc.us> >> http://www.ihmc.us/users/__phayes >> <http://www.ihmc.us/users/phayes> >> >> >> >> ------------------------------__------------------------------ >> IHMC (850)434 8903 >> home >> 40 South Alcaniz St. (850)202 4416 office >> Pensacola (850)202 4440 fax >> FL 32502 (850)291 0667 >> mobile (preferred) >> phayes@ihmc.us <mailto:phayes@ihmc.us> >> http://www.ihmc.us/users/__phayes >> <http://www.ihmc.us/users/phayes> >> >> >> ------------------------------__------------------------------ >> IHMC (850)434 8903 home >> 40 South Alcaniz St. (850)202 4416 office >> Pensacola (850)202 4440 fax >> FL 32502 (850)291 0667 mobile >> (preferred) >> phayes@ihmc.us <mailto:phayes@ihmc.us> >> http://www.ihmc.us/users/__phayes >> <http://www.ihmc.us/users/phayes> >> >> >> >> >> >> >> >> > > > >
Received on Monday, 29 December 2014 18:52:58 UTC