There seems to be a lag in my messages being posted, so I hope this isn't
out of order (a previous post had some example data tables)
Lars, I am afraid I have misrepresented my goals. I am not trying to "
implement a topic map in a relational database". What I am trying to do is
develop a data store, for which a variety of input processors can dump
data. These inputs could be in RDF, XTM, or more typically some XML
language like RSS. The idea is not to directly support a topicmap
application, but to provide a data store that "marks all the distinction
boundaries for incoming data" and allows merging based on identity. The
goal of these input processors is to provide a common repository for
heterogeneous data that preserve the identity based information within the
input. Output processors could then be written that could cast/collapse
this data into a (typically XML based) output format (based on the
distinctions that make a difference) and that supports a variety of
semantics unanticipated by the input source. These output formats could be
XTM, RDF, merged RSS Feeds etc. and involve a great deal of filtering and
aggregation. A round trip from XTM to data to XTM would probably not
preserve the original syntatic structure (although a system like that is
certainly possible).
See XML vs RDF NxM vs N+M
http://bitsko.slc.ut.us/blog/xml-vs-rdf.html
Thanks for the feedback
Guy
* Guy A. Lukes
||
|| But in my resent attempt (with Bryan Thompson) to implement a topic
|| map in a relational database, I was shocked to discover that the
|| underlying database structure was only a slight modifications of RDF
|| triples.
||
|| The Subject is the a-node
|| The predicate is the r-node
|| The object is the x-node
||
|| All that was missing was a c-node to reify the triple
|| and a set of PSIs to implement subject roles (predicates/r-nodes/roles)
to
|| support topicmap merging behavior.
||
|| This gives you the simplicity of the semantics free RDF triples,
|| with the power of topicmap subjects and merging (if you need it),
|| plus the ability to leverage all work that is going on in the RDF
|| community.
||
|| Is there something I am missing, that is going to cause be problems
|| down the road?
*Lars Marius Garshol
|Well, what you describe here does not have any obvious resemblance to
|topic maps as they are described in ISO 13250:2000 or ISO 13250:2003,
|nor to anything that is currently scheduled to go into the next
|edition of ISO 13250. In short, it's not clear that what you describe
|here could be called topic maps. It certainly does not follow any
|published standard by that name.
|Also, what you describe sounds like the Topic Maps Reference Model,
|and while I am no expert on the RM it does sound to me like you may
|have omitted parts of it. We'd need to see the RDBMS schema to be
|sure, of course, but that's my impression.
|
| 
