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RDF Next

RDF Next. Ivan Herman W3C. History. Current RDF has been published in 2004 Significant deployment since then implementation experiences users’ experiences Some cracks, missing functionalities, etc, came to the fore There are significant communities that have not picked up RDF

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RDF Next

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  1. RDF Next Ivan Herman W3C

  2. History • Current RDF has been published in 2004 • Significant deployment since then • implementation experiences • users’ experiences • Some cracks, missing functionalities, etc, came to the fore • There are significant communities that have not picked up RDF • e.g., Web Developers

  3. The question • Shall we • live with those issues and go on with our lives? • dump it and start all over again from scratch? • do some minimal changes?

  4. The W3C “RDF Next Step” Workshop • W3C organized a Workshop in June 2010 • 32 submissions, 28 accepted, 18 were presented at the workshop • 2 busy days at Stanford (courtesy of NCBO)

  5. What we did… • Try to answer the question: live with it, redo it, mend it… • if something has to be changed, what is it and with what priority? • Give a list of possible work items, with priorities

  6. The general feeling… Yes, it is probably o.k. to touch some issues But we have to be verycareful not to send the wrong signal to adopters, tool providers, etc. I.e.: keep the changes to the minimum

  7. The straw poll result

  8. Follow up • Workshop report published: • http://www.w3.org/2009/12/rdf-ws/Report.html • W3C Team began working on chartering • …but felt the larger community should be asked • A questionnaire was published in August 2010 • http://www.w3.org/2002/09/wbs/1/rdf-2010/results • And, of course, lots of discussion on various fora

  9. In what follows… • I will list the major items that came up during the discussions • mostly the Workshop+Questionnaire, plus some others • I will list them in the order of • may end up in the RDF Working Group Charter • should be done but not clear yet where and how • postpone it for now

  10. “Charter candidates”Part I: required features

  11. The obvious issues • There are some errata that have to be taken care of • exact relationship to IRI-s • more flexible references to XML versions • etc • Not worth discussing them here

  12. “Graph identification” • A.k.a. “named graphs”, “quoted graphs”, “knowledge bases” • Is on the top of all priority lists… • But the semantics is not absolutely clear • e.g., are we talking about a mutable or immutable collection of triples? • maybe we have two different concepts here…

  13. Turtle serialization syntax • We have a stable “team submission”, widely used by the community • another top priority item… • Additional syntax should be added for graph identification

  14. JSON serialization syntax • Is essential for Web Developers • The syntax may not be a complete syntax; to be decided as we go • e.g., no blank nodes, only syntax for Skolemizednodes • The syntax may also include tools for lists, graph identification, etc. • Note that it may make sense to separate that into a different group…

  15. Deprecation • Some features may be deprecated: reification, containers, … • Unclear what “deprecation” means in this context • old RDF graphs should not become invalid…

  16. Reconcile semantics documents • A number of semantics extensions and features have appeared in Recommendations since • rdf:plainLiteral • “finite” versions of RDF(S) semantics as part of the SPARQL 1.1 entailment regimes • bridge between URI-s as strings and RDF resources in POWDER • Probably useful to reconcile these in one place for wider and easier adoption

  17. “Charter candidates”Part II: time-permitting features

  18. Atom, oData, gData… • oData, for example, is gaining ground: • “…Web protocol for querying and updating data that provides a way to unlock your data and free it from silos that exist in applications today” • Relationship between RDF and these should be defined • oData/Atom based serialization of RDF?

  19. BnodeSkolemization • General guidelines for bnodeSkolemization • e.g., define a scheme of the form • http://bnode.w3.org/{uuid} • … that could be used by some syntaxes, ie, consumers would know that this is, in fact, an anonymous node • There are a number of Recommendation that rely on Skolemization (e.g., SPARQL)

  20. Harmonize plain literal management • We currently have plain literal, xsd:string, rdf:plainLiteral… • it leads to, e.g., convoluted SPARQL queries • These should be harmonized

  21. Update the RDF Primer • Refresh the vocabulary examples being used • Multi-syntax example (like, e.g., the OWL documents) • Linked Data guidelines should be included • “follow your nose” • usage of owl:sameAs or others • etc.

  22. “Work candidates”(not yet clear where and how)

  23. “Create standard for deployment of linked data • Issues that arose: • httpRange-14 as a standard • “Cool URI-s for the Semantic Web” • “follow your nose principles” • social contracts around URI-s • etc. • Not clear that these should be Recommendations • Some of the issues might become part of a renewed RDF Primer

  24. Provenance Clearly a major problem to be solved There is a general requirement (graph identification) that is part of the RDF Core W3C may start a separate group on Provenance vocabularies

  25. RDFS++/RDFS 3.0/OWLPrime • Goal: define a subset of (essentially) OWL 2 RL • more palatable to developers • can be “referenced” as an entity, not only a set of rules • Should be done, not clear where and how • not clear this should be part of an RDF Core • would a SWIG Note be enough, or does it need a full Recommendation status?

  26. Similarity/equivalence properties • Mainly on the Linked Data Cloud owl:sameAs is widely used • the usage is not necessarily semantically correct • a vocabulary should be defined to reflect the various usages • could be very close to the relevant SKOS terms, actually… • Some elements may be part of an updated RDF Primer

  27. Namespace packaging mechanism • A bit like RDFa 1.1’s profile mechanism • a single file that collects all namespaces in one • May find its way as part of the JSON serialization • not explicitly out of scope, but has not been added as a requirement either

  28. RDF API-s Mainly the Web Developers’ community needs API-s But there is already an established set of API-s in Java, Python, etc The RDFa API work defines its own API which includes a more generic RDF API mainly for Javascript Not clear whether a separate group would be necessary…

  29. No work planned

  30. RDF/XML improvements • RDF/XML is generally disliked • no one wants to spend time on improving it… • New features (e.g., graph identification) may not find its way to RDF/XML

  31. Redo the RDF Semantics • There is a disconnect between the formal, model-theoretic semantics of RDF(S) and applications • there are also theoretical inadequacies, too • But the overall feedback was: don’t touch it, deployment has learned to live with it, etc.

  32. Remove RDF restrictions • Bnodes as predicates, literals as subject • Literals as subject has deeply divided the community • some are violently against it, others ask for it • clearly no consensus at the moment!

  33. And now? • W3C team should finalize the charter soon • Then the W3C process kicks in • AC members vote with a yea or nay • if the vote is positive: work can begin in early 2010

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