Archives for: April 2009

Monday, April 6th 2009

Permalink 09:54:52 am, Categories: Meeting summaries

The What and Why of the Third Last Call

Since making our second Last Call for comments at the end of last year we've responded to all of them and have been completing work on the tools - the processors, the XSLTs and so on - all of which has now been done.

So why aren't we at PR yet? There are a couple of reasons for this. There has been an ongoing battle between (WG member) Stasinos Konstantopoulos and (W3C team member) Eric Prud'hommeaux over whether the POWDER Semantic extension applies to the data layer or the application layer. The two protagonists have agreed to differ whilst the document has gone forward.

The second issue that has arisen concerns the other area that has prompted a lot of comment - the canonicalisation section of the grouping doc. Despite many changes over the last year or so and input from the Internationalisation WG, (W3C team member) Thomas Roessler spotted more problems with this section.

After a lot of e-mail bouncing around on, I'm sorry to say, a team-only list, I had a long conversation with Thomas and (Semantic Web lead) Ivan Herman. Some context:

The Semantic Web (RDF, OWL, SPARQL etc.) is written solely about URIs, not IRIs. Furthermore, all URIs are opaque strings - they have no meaning. This goes back to Jeremy Carroll's useful distinction between "http://www.example.com" and <http://www.example.com>. In other words, for RDF etc. our issue of processing URIs/IRIs as meaningful strings doesn't arise.

IRIs - that is, URIs written in things like Cyrillic script, Japanese Kanji etc. - are going to be more important in the coming 12 - 18 months (according to Thomas who, among other things, represents W3C at ICANN and so has a good grasp of such things). For POWDER not to be useful now and in the near future across all parts of the Web would limit its potential usefulness.

As we have discovered, the encoding of IRIs and International Domain Names is less than clear. However, there is a recognised path to take in this area which involves converting IRIs into ASCII - essentially converting IRIs to URIs.

It is not the POWDER WG's job or wish to solve the whole issue, neither is it within our ability to do so.

The POWDER to POWDER-BASE transform XSLT doesn't do any of the canonicalisation stuff, and it would be hard, if not impossible for it to do so. Therefore, strictly speaking, some form of pre-processing is already necessary before the XSLT is applied (the Perl script does do the canonicalisation but now needs a bit of work).

Given all of the above, the group was faced with a choice between either making significant edits in all its documents to talk only about URIs or, as we have done, further amending the canonicalisation section to introduce the ToASCII function as defined in RFC 3490. It is this change that has prompted the new Last Call announcement, open until Monday 27 April. The documents published on 3 April to coincide with the Last Call reflect all the changes made following comments received in the previous calls and, with the exception of the highlighted sections of the Grouping of Resources document on canonicalisation, are considered stable.

One important, although editorial, change worth highlighting is in the Description Resources document. The definition of the describedby relationship type and the two POWDER Content Types is much improved. describedby is now included in the IANA registry of ATOM Link relationship types.

The Test Suite has been significantly updated in the 3 April version and is now unlikely to change significantly (we may add some new tests for the canonicalisation section). Perhaps rather perversely, the test suite does include a test for the informative section on HTTP Link. The Primer is considered stable and very unlikely to change further.

Minor adjustments to the POWDER Processors are in progress and, notwithstanding changes prompted by the last call, the group is expecting to go to Proposed Recommendation in May.

Phil ARCHER