DQV, DAQ and Data Cube graphs

Dear all,

While preparing the last mail, Riccardo and I started a longer discussion on which the group's input would be welcome.

This is about the following issues:

http://www.w3.org/2013/dwbp/track/issues/181 - Should we have only the existing class daq:QualityGraph or keep the new class dqv:QualityMetadata?
http://www.w3.org/2013/dwbp/track/issues/182 - The label of daq:QualityGraph does not fit well with the current model -

If we resolve ISSUE-180 [1] by not re-using directly the DaQ elements, we can solve both issues at once. Here are two proposals from me:

PROPOSAL 1: Replace daq:QualityGraph by a new class (say, dqv:QualityMeasureGraph)

PROPOSAL 2: Drop daq:QualityGraph and represent quality measures in graphs of the same class as the other quality metadata (ie., graphs of type dqv:QualityMetadata)

Riccardo has pointed out that we should keep in mind also issue 191 [2] 'DQV backward compatibility with DAQ and Data Cube'.
DaQ has been made consistent with RDF Data Cube (qb: namespace [5]): daq:QualityGraph is a sub-class of qb:DataSet, so that results of the quality measures can be visualised by RDF-cube visualizer (see [3]). This is very useful feature and he thinks we should preserve it in DQV. And I agree.
So when dropping daq:QualityGraph, we have to think where to put the qb:DataSet subclassing and to the rearrange qb:dataSet property in our graph at [4]

Riccardo suggests another (orthogonal) proposal:

PROPOSAL 3: define dqv:QualityMetadata as a subclass of daq:QualityGraph.

With this we keep compatibility with DaQ and Data Cube. We don't have nested graphs anymore - only a graph grouping together all the measures and annotations, and whose provenance can be easily tracked.

The problem is semantics: qb:Dataset is defined as "collection of statistical data" and a daq:QualityGraph "contain all metadata about quality metrics on the dataset". So these are rather numerical observations, while our dqv:QualityMetadata can include more diverse metadata, for example textual annotations.

What do you think?



[1] http://www.w3.org/2013/dwbp/track/issues/180
[2] http://www.w3.org/2013/dwbp/track/issues/191
[3] http://eis-bonn.github.io/Luzzu/papers/semantics2014.pdf
[4] http://www.w3.org/TR/vocab-dqv/#vocabulary-overview
[5] http://www.w3.org/TR/vocab-data-cube/

Received on Wednesday, 26 August 2015 23:13:00 UTC