Revisiting Content Negotiation

I attended yesterday a very interesting telecon of the SWBPD Vocabulary Management Task Force. The agenda was highly technical - define best practices on how to provide through its URI, both computable RDF description for computers and human-readable description for humans, of an RDF vocabulary term. Use cases were SKOS and FOAF, with their respective editors Alistair Miles and Dan Brickley, and Dublin Core, represented by Tom Baker. All those smart guys have already explored the subject in-depth during recent Dublin Core Conference in Madrid, and agreed that current state of their respective vocabularies was suboptimal.

Devil is in the details there, for example many vocabularies use #URIs, such as http://www.w3.org/2004/02/skos/core#prefLabel.

From Topic Maps Published Subjects viewpoint, such an URI would be called a subject identifier, but in your browser, the fragid is not taken into account, because http://www.w3.org/2004/02/skos/core#prefLabel points to an RDF schema. So the subject identifier does not provide directly a human-readable HTML subject indicator, such as the one actually provided by http://www.w3.org/TR/swbp-skos-core-spec/#prefLabel

Everybody agreed that it would be good to have the subject identifier provide redirection to the subject indicator (even if this is not the terminology used so far in RDF land), at least for human users (that is, in a regular browser), whereas computers would keep being fed with the RDF description.

Consensus in this meeting was that content negotiation is the way to go. While it's unclear at this stage (at least for me) how it can be technically achieved, particularly with #URIs, it sheds a new light on Published Subjects specification, on which I expand in this post.

New thing here is that at the time of the specification (2003), we did not explore both possibilities offered and issues raised by content negotiation for Published Subjects.

Thinking further about it, it strikes me that content negotiation mechanism is very similar to hubjects. A URI managed through content negotiation is defining a subject/resource which is neither this content nor that one, but a superposition of all possible contents, the actual one being delivered in a given interaction depending of the client-server dialogue. It's amazing that impact of content negotiation on URI meaning seems to have been so much overlooked. Although the specification is now quite old, it seems to have been only used as a borderline technical trick, whereas it could become a fundamental mechanism to deliver, through the same URI, a variety of views of a subject to a variety of users, humans and computers as well.

Axioms of Identity

Here is what Scott C. Lemon said:

In my research into digital identity, I created a set of 'axioms' that have molded my perspective of the subject. I developed these axioms as the foundation for how I would create a digital identity solution ... a software solution to accumulate identity, and provide controlled dissemination of that information.

The First Axiom of Identity

I posit that we humans do not have any inherent identity.


The Second Axiom of Identity

I posit that identity does not exist outside the context of a community.


The Third Axiom of Identity

I posit that identity is exchanged in transactions that occur within a context of trust and authentication.

nota bene: given the last update on these (4-3-2005), I'm guessing that Bernard didn't already mention them here earlier :)

Thinking about RDF and Topic Maps

Danny Ayers, in this blog entry, talks about issues related to representations in RDF that speak to issues I have thought about for a while now. I think that now is a good time to start a dialog between the RDF tribe and the Topic Maps tribe. It's a double-edged knife, one that cuts both ways, looking at the true nature of the inquiries of each tribe.

I like to think about it this way: the core of the topic maps inquiry is to
satisfy a couple of important use cases: finding and reminding. In
those two use cases lie two primitive notions: subject identity and
names for things. Those are the two primitives that topic maps place
front and center, whereas, it seems to me, OWL emphasizes inferencing in
subsumption hierarchies, relegating subject identity to "proper use of URIs". I like to think about subject identity in the same terms a lawyer might do so in a court case. There, properties of the subject, more so than some URI, become all important. A trial might turn on something as trivial as shoes worn on some particular day. As topic maps are evolving, particularly in the case of the TMRM (topic maps reference model), we are seeing more emphasis placed on comparable subject properties than on precise URIs, which, in many cases, do not (yet) exist. We are seeing the evolution of the ability to "confer" identity on a subject according to circumstances. I think this line of inquiry can map directly into rdf work.

Topic maps (indeed, "subject maps") add one important consideration
outside subject identity and names for things: a guarantee that any
proxy for any subject (aka Topic), is the one place you need to go (in
*this* map) to find all that is knowable about that subject.

The knife cutting in the other direction suggests that, at the implementation level, topic maps could evolve along lines suggested from rdf work. Indeed, some of my own work involves the use of Jena coupled with JDBM for a backside.

GeoRSS

GeoRSS is simple proposal for RSS feeds to also be described by location or Geotagged. It standardizes the way in which "where" is encoded with enough simplicity and descriptive power to satisfy most needs to describe the location of Web content.

This article further suggests to combine this geo-tagging with folkso-tagging, to provide pragmatic but efficient "what-where" identification.

Technorati Blog Finder

Cool new (beta) feature on Technorati. I have added a profile for universimmedia, with a few tags such as this one or that one. Ideas for more relevant tags are welcome.

Semapedia

Semapedia combines the physical annotation technology of Semacode with the availability of high quality information using the free encyclopedia Wikipedia.

Combination of 2D-barcode and bottom-up Published Subject Indicators. Bottleneck is that you need a physical reader on your mobile device, and have to find out physical tags. Next step is certainly to replace the semacode tags by RFID tags.

[2015-02-23] Semapedia is off-line 

Simile Tools

I've posted a few months ago about Piggy Bank, without clearly stating it is but one of the various tools developed by the Simile Project, Semantic Interoperability of Metadata and Information in unLike Environments. All RDF-based stuff, but user-friendly, a qualifier which does not come to mind when looking at some other RDF tools (no names, please). Have a look at Longwell browser, for example. You can try it on-line to find your way through W3C specifications. Local installation requires a bit of Java logistics, not tried it yet.
What people say about what they do is also interesting stuff. I had mentioned Stefano's Lynotype before. Posts are not frequent, but always thoughtful. See e.g. Data First vs. Structure first.