W3C home > Mailing lists > Public > semantic-web@w3.org > December 2013

Re: Deprecate http://www.w3.org/1999/02/22-rdf-syntax-ns# in favour of /ns/rdf# ??

From: Christophe Guéret <christophe.gueret@dans.knaw.nl>
Date: Mon, 2 Dec 2013 15:35:48 +0100
Message-ID: <CABP9CAFE7OyiTFUJtKU0PUn+6TH+R6JTm162tL0=v1RpNnT6dQ@mail.gmail.com>
To: Dan Brickley <danbri@danbri.org>
CC: Christophe Gueret <christophe.gueret@dans.knaw.nl>, Phil Archer <phila@w3.org>, Richard Cyganiak <richard@cyganiak.de>, Charles McCathie Nevile <chaals@yandex-team.ru>, Ruben Verborgh <ruben.verborgh@ugent.be>, SW-forum Web <semantic-web@w3.org>, "team-rdf-chairs@w3.org" <team-rdf-chairs@w3.org>
> Let me try to rephrase the concern. If all we want is to update W3C's
> namespace documents, this is easy. If we want the new URIs to actually be
> used and to be useful, we're in for a world of frustration.
> There are a lot of interacting pieces in the ecosystem around RDF, and
> this is by design --- we made these standards so that data can flow between
> applications. If we want to upgrade this network to understand a new
> equivalence between e.g. <http://www.w3.org/1999/02-22-rdf-syntax-ns#type>
> and <http://www.w3.org/ns/rdf#type> we'll need to say where in the
> information flow we expect this to happen. Parsers, APIs, databases, all
> have the potential to do something, or to do nothing, and will be
> interacting with other components which may also be ignoring or acting on
> the equivalence information. Often an application does not have total
> control of the information that is passed to it, or the nature of the
> storage and other components it uses. In this semi-structured chaos,
> introducing URI aliases is pretty difficult since it is not clear whose job
> it is to deal with them.
> Broadly we can talk about publication and consumption roles, but even
> those are complex when you try to break down who the actors and decision
> makers are.
> Consider someone building on Drupal 8. If D8 uses RDFa, then certain
> pieces of RDFa 1.1 / Lite syntax (notably @typeof) will generate <
> http://www.w3.org/1999/02-22-rdf-syntax-ns#> -based URIs in all compliant
> RDFa 1.1 parsers, regardless of what the publisher or the Drupal team, or
> Drupal extension and theme authors think or do. However, other markup
> idioms are under control of the site publisher, the Drupal software team,
> or other players (themes/addons/etc.), i.e. someone gets to choose whether
> the site writes <http://www.w3.org/1999/02-22-rdf-syntax-ns#type> vs <
> http://www.w3.org/ns/rdf#type> etc.
> People in the position to be making the decision whether to use the old,
> new, or both URIs for rdf:type will try to take into account likely
> behaviour(s) of RDF consumers. Whether parsers will pass on the data in
> 2012/2013 style, or try to modernise it by turning  <
> http://www.w3.org/1999/02-22-rdf-syntax-ns#type> into <
> http://www.w3.org/ns/rdf#type>, or double up the data. Or whether
> rule/inference capable systems are starting to ship that come with built-in
> option to understand both versions of rdf:type transparently. Some of those
> people we put in the position of having to choose old rdf: ns versus new
> rdf: ns will be choosing on behalf of downstream users that they don't know
> much about.
> Generally if word gets around that lots of important tools can deal
> smartly with either, we might see more publishers start to use <
> http://www.w3.org/ns/rdf#type> instead of <
> http://www.w3.org/1999/02-22-rdf-syntax-ns#type>  when they're in a
> position to choose the exact URI. When they're using W3C's existing
> shorthands for these, the decision is still out of their control. This
> might start to put pressure on RDFa implementors to generate the new
> flavour of triples from rdf:type instead of the old; which in turn puts
> pressure on W3C to update the specs. Which rarely happens very quickly.
> Meanwhile, what about people using RDF APIs and storage systems. Consider
> a Python application that uses e.g. rdflib 2.4.2 to write data into (and
> later retrieve from) a remote SPARQL store, where the remote store could be
> based on any version of Virtuoso, ARC2, Jena or Sesame. The data transfer
> could be via toolkit-specific APIs or via
> http://www.w3.org/TR/sparql11-update/. The exact nature of the data being
> managed is not under the control of the application author (e.g. it might
> partially come from XMP extractions from PDF, or from RDFa parsing, etc.),
> and so might contain various triples either using <
> http://www.w3.org/1999/02-22-rdf-syntax-ns#type> or <
> http://www.w3.org/ns/rdf#type> or both. Should the Python app expect to
> be able to get back from these databases the exact set of triples it
> inserted? Is it reasonable for the databases to say "that's a matter for
> the application, we're not messing with the internals of user data"? or
> "we'll normalize all data we see to modern form.". Whose job is it to
> implement the equivalencies between old-rdf:type and new-rdf:type? If
> old-style or partially old-style data is transmitted via programmatic or
> REST/SPARQL API, should the sender or the receiver be normalizing it?
> Should data access mechanisms - APIs, SPARQL or other query languages e.g.
> Gremlin - reflect the actual form of data, or its
> idealized/modernized/normalized form?
> As far as SPARQL is concerned,
> http://www.w3.org/TR/sparql11-entailment/#entEffects therefore seems
> relevant. You can then think about querying the 'raw' data (for years,
> likely and mix of old and new rdf: namespace URIs) or perhaps a
> virtual/abstract modernized graph if the database exposes it as an
> entailment regine. But we you have the problem of trying to second-guess
> what applications want, e.g. which behaviour should be the default, what
> non-SPARQL data access methods should do, etc.
Ok, now I think I see your point. It is indeed problematic to settle on one
way to share data when to equivalent notations are in use, either some side
of the work-flow will have to use both and/or the other end will have to
ensure it reads both. If they both go for supporting only one option and
this happens not to be the same the communication is broken. We are already
having such issues with, e.g., using http://schema.org/Person VS
foaf:Person which seems to settles down to data publishers using both and
data consumers looking for the one they prefer... probably best to avoid
creating more such cases.

It's a pity, I still think it would have been neat to have all the W3C
vocabularies under one name :-/

 I'm still finding it hard to be optimistic about the prospects. What's the
> alternative? Maybe to try to find ways to make it easier for specialists to
> remember at least the rough dates?
So far, I rely a lot on copy&paste and prefix.cc . I just can't remember
what the prefixes of RDF, RDFS and FOAF are. I always have to do some kind
of look-up

> Maybe instead we could start to celebrate "RDF Day" as Feb 22nd 1999?
> 1999/02/22-rdf-syntax-ns ->
> http://en.wikipedia.org/wiki/February_1999#1999_February_2
> We could remember what else happened on that day?
> http://articles.baltimoresun.com/1999/feb/22 ... and then help RDF
> developers / publishers remember what was added via RDFS the following
> January by associating it with "what happened after Y2K? In RDFS's
> namespace, from January 20000, W3C added subPropertyOf, subClassOf, Class,
> range and domain to RDF(S). What was RDF before that? Something quite
> minimal that had a very basic notion of structured data graphs using
> properties (rdf:Property) and where some things had a relationship called
> rdf:type to some other things, but which waited for RDFS before we said
> "and the value of an rdf:type is an rdfs:Class; and the meaning of a
> property can be described through its associations to classes (which form
> hierarchies) and to other properties (which also form hierarchies), hence
> rdfs:subClassOf, rdfs:subPropertyOf, rdfs:domain, rdfs:range". At some
> point we still have to confess to rdf:resource being syntax and
> rdfs:Resource being a type, and to rdf:datatype being syntax and
> rdfs:Datatype being a type. But at least there's some rough symmetry there.
Love it! That way the Web of Data not only contain the data and their
associated semantics, it also embed the history of the creation of these
vocabularies. As long as nobody sees the dates as version but only as
historical pins this is rather cool :-)


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Received on Monday, 2 December 2013 14:36:40 UTC

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