1 © NOKIA 2/12/ Ora Lassila 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

2 © NOKIA 2/12/ Ora Lassila RDF Timeline 1997 SpringPre-WG work (e.g., PICS-NG), authors MIT 1997 SummerM+S Working Group chartered, M+S first draft (for group review) 1997 OctoberM+S first public draft 1997 NovemberRDFS Working Group chartered 1998 AprilRDFS first draft (for group review) 1998 OctoberM+S goes to last call 1999 JanuaryM+S goes to proposed recommendation 1999 FebruaryM+S goes to recommendation! 1999 MarchRDFS goes to proposed recommendation 1999 AugustRDF Interest Group formed 1999 OctoberThe Cambridge Communiqué published 2000 MarchRDFS goes to candidate recommendation

3 © NOKIA 2/12/ Ora Lassila Motivation library metadata (Dublin Core) content rating (PICS) site maps some other applications…

4 © NOKIA 2/12/ Ora Lassila 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 © NOKIA 2/12/ Ora Lassila 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 © NOKIA 2/12/ Ora Lassila 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 © NOKIA 2/12/ Ora Lassila 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 © NOKIA 2/12/ Ora Lassila Mysteries of Domain & Range yx pc type domainClass type Property type

9 © NOKIA 2/12/ Ora Lassila Other Issues Dueling press releases Netscapes love for RDF vs. Microsofts 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 © NOKIA 2/12/ Ora Lassila Questions? Lauren Lassila (age 3 months) finds the RDF Design Rationale a perfect bedtime story. yawn…