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 _at_ MIT
• 1997 Summer MS Working Group chartered, MS
  first draft (for group review)
• 1997 October MS first public draft
• 1997 November RDFS Working Group chartered
• 1998 April RDFS first draft (for group review)
• 1998 October MS goes to last call
• 1999 January MS goes to proposed recommendation
• 1999 February MS 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
Mysteries of Domain Range
9
Other Issues

• Dueling press releases
• Netscapes love for RDF vs. Microsofts marketing
  message
• a lot of the RDF MS 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?

• mailtoora.lassila_at_nokia.com
• mailtodaml_at_lassila.org

yawn
Lauren Lassila (age 3 months) finds the RDF
Design Rationale a perfect bedtime story.