POWDER Working Group Blog

The first meeting back after the summer break began with a quick update of the current situation. The Use Cases document has been published in its updated, and hopefully final, form. We need to get an updated version of the Grouping of Resources document and a First Public Working draft of the Description Resources document done on the next couple of weeks ahead of various meetings at the end of the month that provide an excellent platform for promoting the group's work. Most of the meeting was spent working through the latest (member only) version of the DR doc. The issue of whether Descriptors should be linked from the DR or from the Resource Set will be resolved on the list in the next couple of days (where it's easier to show examples and list pros and cons) but the trend is towards linking from the RS. The textual summary of a DR (provided using dc:description) will normally be a summary of the whole DR but this doesn't prevent a dc:description being provided of, say, just the Descriptors. The discussion then turned to how to express package scope. The resolution was that as a minimum, you SHOULD defined a white space separated list of hosts covered by a package (using wdr:aboutHosts) and you MAY further define an RS but be warned that not all processors will honour it. Package scope is a processing hint - the DRs in the package are not guaranteed to cover all the resources given in the package scope. Work is being done on showing how to use DR data in a rules-based environment. It is anticipated that this will show how the data can be expressed precisely and efficiently and may lead to further improvements in the spec. The group discussed how to include multiple blocks of Descriptors in a single DR. The idea of a separate wdr:include predicate for this purpose was dropped in favour of simply using a parseType="Collection" attribute on the hasDescriptors predicate. The section on efficient data representation (using XML entity declarations etc.) will be moved the the POWDER Primer but will be referred to in the specification document. Finally, a proposal to make includeHosts mandatory in Resource Set definitions was not approved. Individual DR creators (a.k.a. labelling authorities) may operate Web Services where includeHosts is guaranteed to be present but this need not apply universally.