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Ora Lassila Research Fellow, Nokia Research Center December 2000

“I Was There…” – Memoirs of an RDF Working Group Member or Observations about the RDF Design Rationale. Ora Lassila Research Fellow, Nokia Research Center December 2000. RDF Timeline. 1997 Spring Pre-WG work (e.g., PICS-NG), “authors’ meeting” @ MIT

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Ora Lassila Research Fellow, Nokia Research Center December 2000

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  1. “I Was There…” – Memoirs of anRDF Working Group MemberorObservations about theRDF Design Rationale Ora Lassila Research Fellow, Nokia Research Center December 2000

  2. RDF Timeline 1997 Spring Pre-WG work (e.g., PICS-NG), “authors’ meeting” @ MIT 1997 Summer M+S Working Group chartered, M+S first draft (for group review) 1997 October M+S first public draft 1997 November RDFS Working Group chartered 1998 April RDFS first draft (for group review) 1998 October M+S goes to “last call” 1999 January M+S goes to proposed recommendation 1999 February M+S goes to recommendation! 1999 March RDFS goes to proposed recommendation 1999 August RDF Interest Group formed 1999 October The “Cambridge Communiqué” published 2000 March RDFS goes to candidate recommendation

  3. Motivation • library metadata (Dublin Core) • content rating (PICS) • site maps • some other applications…

  4. Model • Ora (from PICS-NG): frame-like model • Guha: understanding which statements have been asserted, and which ones have not • WG charter included mandatory PICS support • certain features, which cannot really be implemented in the model itself, crept in (“aboutEachPrefix”) • Acceptance & deployment was very important • “just simple enough” for the WWW community at large to accept and deploy • “not too offensive” for the KR community so it could be used as a starting point for something better • main challenge: managing expectations

  5. Syntax • Naming (e.g., “Pumpkin”) • S-expressions vs. XML • in some sense, the choice of XML was an unfortunate one, because it leads to a lot of confusion • Namespaces were deemed necessary, and consequently an XML NS spec which supports RDF needs was “rammed through” at W3C • issues with the namespace of attributes like “about” • Interpretation of literals • XML Schema was supposed to provide “primitive” datatypes

  6. Details, Details, Details, … • RDF is supported by a number of other standards • XML • URI • HTTP (caching semantics) • … • It is important to understand that RDF takes care of a lot of “dirty details” which we now no longer have to worry about

  7. Type System & Ontology - RDF Schema • Basic definition of “Class” • defined as a prototype rather than a classification • Metaclass issues proved to be hard • ANSI X3J13 as an inspiration, but simplified • class Class and “class Metaclass” are the same thing • “DisjointWith” and cardinalities: discussed but eventually rejected • Domain & range proved to be hard (for the WG) • “subPropertyOf” vs. “subClassOf”

  8. Property type type type domain Class type type p c type y x “Mysteries” of Domain & Range

  9. Other Issues • “Dueling press releases” • Netscape’s love for RDF vs. Microsoft’s marketing message • a lot of the RDF M+S work happened at the height of the so-called “browser wars” • WG member troubles • skill/experience vs. technical complexity mismatch • RDFS vs. XML Schema • cf. the “Cambridge Communiqué” • RDFS still not a recommendation…

  10. Questions? • mailto:ora.lassila@nokia.com • mailto:daml@lassila.org yawn… Lauren Lassila (age 3 months) finds the RDF Design Rationale a perfect bedtime story.

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