A continuation of the conversations that started in Montreal at the Extreme Markup Languages Conference to increase knowledge and understanding about the relationships between the W3C RDF and ISO/XML Topicmap activities.
[[[ Relationship of XTM and RDF The actual and potential relationship of XTM and RDF was discussed, since there had been public comment about this issue during the Extreme Markup Languages Conference immediately preceding the XTM meeting in the same hotel. Specifically, conference co-chair Michael Sperberg-McQueen had suggested in his closing keynote that the RDF people and the Topic Maps people should be locked in a room together until they have harmonized the two standards. A "summit" meeting on this issue has been proposed by Eric Miller, who would host such a meeting at OCLC. The AG, with the help of its three Subgroups, needs to: - Understand the relationship, if any, between the XTM conceptual model and RDF conceptual model, - Understand what realistic opportunities exist for establishing one or more syntaxes that will be common to both Topic Maps and RDF, if any, and - Understand the Use Cases, if any, that compel harmonization or unification of Topic Maps and RDF around either their conceptual models or their syntactic models, or both. ]]] -- XTM Agenda http://www.egroups.com/files/xtm-wg/Meeting+Agendas+%26+Summaries/minutes0823.htm Thu, 01 Jan 1970 00:00:00 GMT
Steve, Michel, could you reiterate again the differences between ISO Topicmaps and the XML Topicmap activities.
[[[
Facing the conflict between Topic Maps and RDF head-on, the
conference staged a debate between Eric "RDF" Miller of OCLC and Eric
"Topic Maps" Freese of ISOGEN[10]. Freese and Miller provided this
comparison between the two specs:
Similarities between RDF and Topic Maps
Both specifications
are hard to read
share a goal: to tie semantics to document structures
provide a systematic way to declare a vocabulary and basic
integrity constraints
provide a typing system
provide entity relationships
both work well with established ontologies
The correspondences between the specs look something like this:
RDF Topic Maps
Resource Topics
RDF schema TM templates (proposed)
Properties Facets and association roles
URIs Topic identity, scope
Reification Association IDs
Differences between the two specifications
Topic Maps are not XML-specific and have so far been
standardized for SGML only. The XML Topic Map activity under the
GCA's IDEAlliance is drafting a proposal for such an
implementation. RDF is also not XML-specific, but to date has
been implemented only in XML RDF now has which provides a
standard way to express and link an ontology; such a schema is
proposed for Topic Maps RDF uses XML linking, Topic Maps use
HyTime linking Topic Maps have explicit scoping Topic Maps start
with the abstract layer and (optionally) link to resources; RDF
starts at the resource layer and (optionally) creates an
abstract layer
Modeling Topic Maps with RDF "loses the distinction between topics
and resources," according to Freese.
In preparation for Montreal, he put out a call for suggestions on
how to combine the two to end up with the best that each has to
offer. Here are some of the suggestions:
consider topics as collections of resources (anchors) or links
such that one object can be a link by a link interpreter and a
topic by a Topic Map interpreter
add RDF's frame-based notation to Topic Maps to attach
properties to resources
model RDF as a Topic Map application, gaining the scoping,
merging, and inheritance mechanisms
David Dodds provided one view of an RDF/Topic Map alliance in his
paper, "Simultaneous Topic Maps and RDF Metadata Structures in SVG."
[11] In this application, he embedded Topic Map constructs in RDF
metadata within SVG resources. With this notation, a graphics
application would then know that a bar chart is a bar chart, and that
each bar represents a certain scale and quantity. Since the RDF is
embedded in a map, an external Topic Map processor can also
manipulate the image.
Freese's example of the best of both worlds would look like this:
<topic xlink:type="extended"...etc...>
<resource xlink:type="locator" xlink:href="...etc..."
rdf:type="dublinCore">
<dc:author>Dr Livingstone</author>
<dc:language>english</language>
...etc...
</resource>
</topic>
This example attaches a set of properties to a locator, which is a
link. The topic could also be an RDF frame and, therefore, could
contain any kind of property.
The reaction of the user community in Montreal was strong and
unequivocal: merge the two or at least make them compatible.
Among the desirable outcomes that were mentioned was a new
syntax for RDF that would retain the graph notation but be less
difficult to use.
]]]
--
XML.com - Part 2 - Going to Extremes
http://www.xml.com/pub/2000/09/13/extremes2.html
Thu, 01 Jan 1970 00:00:00 GMT
Useful simply to start listing examples:
Should we consider establishing a public archived mailing list for RDF <-> TopicMap discussions, or are we all happier working in private cc:'s initially? If public, whats the name, where?
Where, when, does this forum (teleconference && IRC) work?