wdrs:issuedbyproperty will be defined as being a class that includes, but is not limited to,
dcterms:Agent. Resolving this also made clear that a POWDER-S document is an
owl:Ontology, not an
owl:Thingwhich has implications for what can and can't be said out it. Finally, we discussed the QA requirements as they relate to the various Rec Track documents. Conformance sections to be added! Activity in the next week should take us very close to being ready to seek transition to CR for the 3 Rec Track documents. A POWDER-S processor already exists (at NCSR as part of the Quatro Project) and at least one POWDER Processor is nearly complete. The group decided at its last face to face that the CR exit criteria would be two POWDER Processors and one POWDER-S processor - so we're well on target.
displayiconcould appear more than once in a DR. Since a DR may have any number of descriptor sets, and OWL (POWDER-S ) doesn't restrict cardinality of properties it's clear that multiple strings and icons may be presented to a user agent. Since it is not clear how a given UA would handle this situation, the Description Resources document will be amended to advise DR authors only to provide one string and one image to display.
<issuedby>in POWDER will be transformed into the
wdrs:issuedby property in POWDER-S. Whilst there remains some uncertainty about what this points to (
wdrs:Agentwhich would either be a union of or sub class of the other two), the XML schema and POWDER-S vocabulary are unaffected and so can be updated quickly. Secondly, following on from the last call comment and subsequent e-mail discussion last month, for the time being at least we are going to use 'describedby' as our relationship type and propose two MIME types for POWDER and POWDER-S. These will be text/powder+xml and application/powder-s+xml respectively which we believe to be in line with RFC 3023, section 2 of which includes "If an XML document -- that is, the unprocessed, source XML document -- is readable by casual users, text/xml is preferable to application/xml. [..] Application/xml is preferable when the XML MIME entity is unreadable by casual users." These are not formal resolutions of the group but indicate our current thinking. The issue of @rel registration is being discussed in various groups, not least the Semantic Web Coordination Group.
The group discussed a number of issues related to its charter, in particular the proposed timeline of Last Call on the grouping and DR docs by end April allowing transition to CR before the summer break. The Primer and Test Suite should be in the public domain, although not as far advanced by end April too. This presents the group with a lot of work to do and we must be mindful of what is practical within that time frame, however, the pieces are coming together.
The group is beginning to plan a face to face meeting in June to go through Last Call comments, probably in Darmstadt hosted by Deutsch Telekom. We will need to avoid a clash with the Mobile Web and Voice Browser meetings that month.
Specific topics: how we will document the rules for transforming POWDER into POWDER-S. Various options have been proposed including some sort of formal rule language or detailed documentation within the XSLT. The group resolved to include a natural language description in the documents and provide both the XSLT and the Test Suite - which should be ample material to allow an independent implementation of a transformation engine.
The general rule for the transformation is:
ref -> rdf:resource, string -> literal (possibly typed), elements assumed to be embedded RDF/XML.
That is, if you want something to end up as a
rdf:resource, encode it in the XML as a
ref and so on. RDF/XML may be embedded within the POWDER Doc.
We also briefly discussed the proposal that all IRI constraints should be expressed in POWDER-S as regular expressions. This will minimise the number of extensions needed to existing RDF/OWL tools. Implementing the full set of IRI constraints would require much more work in such tools.
The POWDER WG held its second outreach event on 18th March, hosted by the GSM Association. The event provided an opportunity for our guests to learn what POWDER is and how it can help to delivery more targeted, personalised content to the benefit of content providers and consumers alike. Carl Taylor from Hutchinson Whampoa gave a positive assessment of the technology but warned about the problems that slow adoption could pose and the task ahead to convince content providers of the benefits of adding metadata, no matter how trusted and useful it may be. Another guest, Scott Rose from Arqiva, talked about the difficulty, cost and therefore resistance to adding metadata to large repositories of video – something that POWDER is designed to streamline by allowing data to be applied to many different resources at once.
As well as a series of short presentations of the various use cases, Paul Walsh of Segala and Charles McCathieNevile of Opera Software both demonstrated POWDER being used in user-centric applications. Putting on events like this not only helps to spread the word about the technology, it’s also very useful for WG members to get first hand feedback from potential users. The group hopes to organise further outreach events later in the year.
The following presentations from the event are available as PDFs:
<wdr:includeHosts>example.org example.com</wdr:includeHosts>More details will be presented in the technical documents, however, the general approach is now agreed. It meets the difficult challenge of creating a system that can work in the day to day, non-semantic web scenarios envisaged in the use cases whilst allowing the data to be processed within a semantic web environment. Several other issues were discussed, such as potential implementations, the test suite, exit criteria for Candidate Recommendation and so on, but the headline from the meeting is clear. After a period in which the group's fundamental approach has been questioned (and was very nearly jettisoned), there is a feeling that the work is back on track. The group records its thanks to NCSR for hosting the meeting, welcomes the interest from its guests, and records its gratitude to Jeremy Carroll for his insight and clear explanations.