Semantic Web and Web 2.0

In this podcast we feature a conversation between George Siemens, Associate Director of the Learning Technologies Centre at the University of Manitoba. and Michael Wesch, Assistant Professor of Cultural Anthropology at Kansas State University It was recorded at the ELI 2008 Annual Meeting.

Michael Wesch presented a session entitled, "Human Futures for Technology and Education" at the ELI 2008 Annual Meeting. He also produced a video, which is referenced in this conversation, entitled "The Machine is Us/ing Us".

George Siemens presented a session entitled, "Connectivism" at the ELI 2008 Annual Meeting.

It seems to me a natural consequence of the increasing bridging of traditional data sources into RDF is that the number of "walled gardens" of RDF is increasing. Walled gardens are areas from which there is no escape, and while they certainly have their uses (in particular controlling who can access what), they erode the overall usefulness of the system as a whole, by meaning that you literally can't get to there from here.

Examples of RDF walled gardens include the FOAF generated by such systems as tribe.net and livejournal. While it is useful that these sites are exposing data in a machine readable web 2.0 format such as RDF/FOAF, the inability to link to people, resources and interests outside the walled garden represent a significant barrier to interoperability. I am the same person in my blog RSS feed, my flickr photo feed, my del.icio.us feed , my tribe FOAF and my hand-edited FOAF, but only the last can I link to the others, despite the fact that they are all in the same format.

I've been tinkering with RDF for a while now, and it's great to see so many sites generating RDF of one kind or another, whether it's RDF/RSS news feeds, RDF/FOAF personal information, RDF/EXIF photo information or RDF/Dublin-core information on documents. Unfortunately there's a little fly in the ointment: people aren't validating the RDF they're creating to ensure that it is valid RDF.

The two most common mistakes are:

• unescaped "&" characters, which result in output that isn't even XML, let alone RDF. This mistake seems to be found most frequently in RDF generated from content management systems and blogging platforms. The solution is to escape the & as &.
• missing namespace declarations, which seems most common in hand-edited and small-scale RDF. The most popular namespace to forget appears to be that for the "rdf" prefix, presumably because some tools have a sensible default for this and somehow this default doesn't make it into the final file.

In the last week I've seen literally hundreds of files with each of these errors. 

In the last two-three years a huge amount has been written about tagging and folksonomies, much of it with the bright-eyed enthusiasm of those who haven't seen the present state of affairs in a broader light; but where is the fight-back from the formal classificationists, who hither-to ruled unchallenged in this area? Have such giants as the Library of Congress and the Dewey Decimal System fallen at the first hurdle?

Tagging is the assigning of arbitrary tags to content by amateurs (typically content creators, editors or readers) and folksonomies are systems built from the ground up using these tags. Tags have no formal meanings and there are no constraints placed upon them. Folksonomies are central to systems such as flickr, del.icio.us and the whole web 2.0 approach.

Formal classifications, such as the the Library of Congress and the Dewey Decimal System are rigorous systems in which trained individuals assign subject categories to content. Each category has a description and is long lived—categories don't change even when the words used to describe the topic in popular culture change. Thus the LoC still calls cars automobiles, because that's what they were called when they first entered the system.