Semantic Web Best Practices and Deployment Working Group
Vocabulary Management Task Force (VM)
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This task force of the Semantic Web Best Practices
and Deployment WG is in support of the group's chartered aim of
supporting the deployment in RDF/OWL of structured
- Thomas Baker <firstname.lastname@example.org>
(Goettingen State and University Library), Coordinator
- Dan Brickley (W3C)
- Libby Miller (Asemantics)
- Alistair Miles (CCL)
- Ralph Swick (W3C)
The following documents are Editor's Drafts, prepared for discussion by
SWBPD-WG prior to formal publication:
- To define (in a Note
or Editor's Draft) a set of good-practice "recipes"
for configuring an Apache server for content negotiation such that:
- If a person tries to dereference the URI of a class or
property (i.e. via a Web browser), they end up at
the relevant bit of human-readable documentation.
- If a machine tries to dereference the URI of a class
or property, they end up with a serialisation of a set of
RDF statements describing that class or property, with
a provenance that allows differentiation of different
'versions' of an RDF schema/ontology.
- The dereferencing solution complies with TAG resolution on
- To wrap those recipes in enough context to make
them usable by vocabulary maintainers to provide
documentation and schemas for their vocabularies.
- URIs based on PURL.ORG. DC, RSS, and vocab.org
use URIs based on purl.org, which currently responds
to GET requests with 302 (Temporarily Moved). The
TAG decision on httpRange-14 requires
303 (Redirect). This was discussed in a mailing
list thread. In July, Dan
asked TAG whether a 302 response on a
purl.org URI would be acceptable. As of November,
Alistair has included purl.org scenarios in the draft
- Awareness of multiple representations. If content
negotiation is handled in the background and alternative
representations of a vocabulary in RDF or HTML are served up
to a user seemingly automatically -- on the basis of Apache
configurations -- how would an interested user know which
other representations were available? Should there
be some way for a user to learn about other representations
(e.g., via cross-references or an overview page)?
- Notion of a "Definitive RDF description".
Peter Patel-Schneider has questioned the focus
on one "definitive RDF description" for each
RDFS/OWL class, property, or individual -- as
opposed to an RDFS description, an OWL description, or
multiple "definitive" descriptions.
- Provenance and URIs. Provenance is supported by using
the final URI from the chain of redirects as the name of
the graph; different URIs represent different versions of a
vocabulary. Tom has noted that, in practice,
"date-stamped" URIs are often used
and suggests we explicitly acknowledge
both that URI strings are in theory opaque and unparsable
and that there are de-facto social conventions for using
date stamps or version numbers.
- rdfs:isDefinedBy. Clarifying the dereferencing
options provides an opportunity to clarify good practice for
the use of rdfs:isDefinedBy. Instead of relying on
URI string manipulation in an attempt to heuristically
locate a namespace, namespaces should be declared with
- Change management for RDFS/OWL ontologies.
There was discussion on whether this should
more properly be called "change management"
or even "version documentation". Current DCMI
practice has been described. The emerging consensus is
that it is best to version the description of a property
(i.e., the RDF statements about it), not the property
itself. I.e. each 'version' is a named graph; provenance
information can then be used to distinguish between
different descriptions of a property. Alistair notes that
the issues of versioning and change management are coming
to the fore in the OWL community.
- Principles of Good Practice
(see Wiki draft).
- Identify Terms with URIs.
- Articulate and publish maintenance policies for the Terms and their URIs.
- Identify the historical version of a Vocabulary or its Terms.
- Provide natural-language documentation about the Terms.
- Declare the Terms using a formal, machine-processable schema language.
Last updated $Date: 2006/03/07 10:55:51 $ by $Author: tbaker3 $