Archives for: December 2007

Wednesday, December 12th 2007

Permalink 09:24:49 am, Categories: Meeting summaries

Meeting Summary 10 December 2007

The principal discussion point this week was the relationship type to be used on a link element pointing to a DR and what should be returned to a user agent following such a link. This follows the discussion held in Boston last month where Tim BL argued that we should use a link element such as <link rel="meta" type="application/xml+rdf" href="..." /> This should return triples that have the resource as their subject and, perhaps, a link to the full DR. In other words, server-side processing would support existing RDF clients. This creates a minimal barrier to adoption from a client perspective. However, it contrasts with the way the group has been thinking so far which is to define a relationship type of 'powder.' Following such a link would return one or more DRs. The problem is this - if we use the generic rel="meta" system then it's quite possible that the metadata would be extensive - and possibly largely irrelevant to the particular context. How can you get just the data you want? As much as requiring server-side processing presents a hurdle to adoption by content providers, requiring client-side processing presents a barrier to user agent adoption, especially in the mobile market. Somehow we need to make sure that the processing is minimised and always relevant to a particular context - is <this> mobileOK? Is <this> child-safe? These look a lot like potential SPARQL queries? Yes - so maybe we should encode the SPARQL query in the href attribute? We didn't discuss this in detail but it is possible. However, there is a generally feeling that the original rel='powder' approach has merit. Given that we plan to specify not only the semantics of a DR but also an XML schema for it, clients could process the data in a variety of (optimised) ways in narrow circumstances. One idea that was frowned upon was having two different representations of the same thing (i.e. and XML version that could be translated into an RDF version). There's a lot of thinking still to do on this topic but it was good to air the issues.
Phil ARCHER

Wednesday, December 5th 2007

Permalink 11:42:17 am, Categories: Meeting summaries

Meeting Summary 3rd December 2007

The group spent some time this week discussing internal logistics, for example, we have agreed that our next face to face meeting will be in Athens in Monday-Tuesday 21 - 22 January 2008. We then gave some thought to the Primer. Who is it for? What message should it convey? It was agreed that it must inform the reader of what POWDER is for and how to use it but that, of course, it was not meant to duplicate the main specification documents. Work on this will get under way before the end of the year. The final topic discussed was the comments made by the Semantic Web Coordination Group last week, in particular the discussion on reification. Further input will be sought from outside the group but in the meantime, work will progress in the other areas. For example, a new internal draft of the grouping document should be available for review by the group members before the end of the year.
Phil ARCHER
Permalink 11:40:09 am, Categories: Meeting summaries

Meeting summary 26 November 2007

The discussion about the 'new' structure for Description Resources has been actively pursued on the public list and we dare to hope that we're reaching a conclusion. There are many factors to bear in mind. Should we use semantic web technology at all? (yes). Can we just do everything in RDF without OWL? No - that's what we were trying to do and it has the real danger that an off the shelf tool kit would come to the wrong conclusion. OWL can help us to overcome this but there are pitfalls too. Finally, using 'just a bit of OWL' to cover a gap in what we need to express in what is essentially an RDF vocabulary is to miss out on the full expressivity and power of OWL. Is this what we want to do deliberately? Well, it's not that we want to cut off options, more that the use cases do not call for the full expressivity of OWL. In particular, we do not need a system that says 'If a resource has features A, B and C THEN it is X'. We need to be able to say 'ACME testing says that Web site A is an example of _this_' and then to be able to go to ACME testing and ask 'did you really say that?' Unless further comment is forthcoming, the editors will work on new drafts of the primary tech documents over the next week with the hope of getting them in the public domain next week. This will allow others to review what the group's planning and make comments as soon as possible.
Phil ARCHER