3 entries tagged metadata

Topic Maps

I’ve been reading about Topic Maps, an ISO standard that has been augmented with an XML representation.

Topic maps are very similar to the RDF, in that they are all about graphs of topics (representing real-world subjects) connected with associations. The difference is that the Topic-maps paradigm seems easier to understand. Maybe its because they draw a distinction between the topics and the subjects they stand in for, whereas RDF tends to conflate the two. Or maybe its the way a few important relationships (like occurence and instanceOf) are treated specially in topic maps, which makes maps a little less bewilderingly generic.

Topic maps have a system of using URIs to stand in for particular abstract subjects. Separate topic maps using the same URI http://www.topicmaps.org/xtm/language.xtm#en as the subject indicator for the English language know they are referring to the same thing. When they are merged, the corresponding topics will be combined automatically. One of the activities of various topic-map committees is creating published subject indicators for various generically useful types of topic, in order to promote interoperability between topic maps.

Other (meta)data systems use URIs to represent subjects: RDF does (using a weird convention where XML element-names turn in to URIs), RSS 0.9x/2.0 does (inasmuch as category names may be interpreted relative to a domain specified by a URL). It would be kind of cool if we could all agree to use the same subject identifiers, so our various efforts interoperate as much as possible.

Flickr and del.icio.us tags illustrate why worse is better

Recently the term 'folksonomy' has been coined to refer to the use of unstructured keywords to classify and group resources collaboratively ('resources' as in photos on Flickr and links to web sites on del.icio.us). Supposedly the experts on metadata are chagrined to discover that structured keywords, hierarchical taxonomies, and faceted metadata have been outdone by such a simple system. But this approach isn't actually all that new. Read more

RDF, Continued …

Back in the 1990s I used RDF as the model for a metadata database of on-line resources for people living with HIV and AIDS (the SEAHORSE project. Much water has flowed under the metaphorical bridge since then, but yesterday I found myself seriously using RDF for the first time in ages and I thought I would briefly comment on how the state of the art has advanced over the intervening decade. Read more