- From: Peter Ansell <ansell.peter@gmail.com>
- Date: Wed, 7 Apr 2010 09:14:15 +1000
- To: Leigh Dodds <leigh.dodds@talis.com>
- Cc: Linking Open Data <public-lod@w3.org>
In the Annotation publishing pattern section there is the following statement: "It is entirely consistent with the Linked Data principles to make statements about third-party resources." I don't believe that to be true, simply because, unless users are always using a quad model (RDF+NamedGraphs), they have no way of retrieving that information just by resolving the foreign identifier which is the subject of the RDF triple. They would have to stumble on the information by knowing to retrieve the object URI, which isn't clear from the pattern description so far. In a triples model it is harmful to have this pattern as Linked Data, as the statements are not discoverable just knowing the URI. If the idea of the book is to point to quads as the preferred model for publishing Linked Data then it may be okay because the named graph is in each statement to indicate where the statement came from so users just have to recognise that URIs in triples are not linked to retrieval locations, and they should keep the quad extension and use that for retrieval. It seems like a stretch to have this as a valid alternative instead of the easier (in Linked Data terms) pattern of creating new URI's that are equivalent to the other URI, just with one or more extra statements. In the Equivalent Links publishing pattern section there is the following statement: "The relations allow for more fuzzy notions of equivalence and have weaker semantics: skos:exactMatch declares two concepts to be the same but doesn't imply that all statements about one concept are also true of another." Should indicate there that SKOS implies that all of the URIs are philosophically just concepts such as those that exist in taxonomies. To use skos:exactMatch one has to follow the SKOS model through or it doesn't fit, as with the OWL model. Could also explain that mixing OWL and SKOS may not be desirable as SKOS puts importance on URI's and logical statements where OWL completely abstracts over URI's, so there is no knowing whether statements actually originally contained the URI, or whether they were published using the proxy pattern and infact some statements should be interpreted just using the SKOS model and doing it using the SKOS model would be inconsistent with the original idea. In some cases the equivalent links used with the Annotation pattern meana that publishers do not necessarily have control over the statements using their Linked Data URI's, although others may use their URI's to imply different things. Explaining this lack of authority may be good, or could change the recommendations about the Annotation publishing pattern so that users are not encouraged to add extra statements directly to other resources without using some sort of equivalence that requires some sort of reasoning (eg, OWL) to take away the reliance on the original Linked Data URI's that are used to get to the RDF statements. Cheers, Peter On 7 April 2010 01:10, Leigh Dodds <leigh.dodds@talis.com> wrote: > Hi folks, > > Ian Davis and I have been working on a catalogue of Linked Data > patterns which we've put on-line as a free book. The work is licensed > under a Creative Commons attribution license. > > This is is still a very early draft but already contains 30 patterns > covering identifiers, modelling, publishing and consuming Linked Data. > > http://patterns.dataincubator.org > > More background at [1]. We'd be interested to hear your comments, and > hope that it can become a useful resource for the growing community of > practitioners. > > Cheers, > > L. > > [1]. http://www.ldodds.com/blog/2010/04/linked-data-patterns-a-free-book-for-practitioners/ > > -- > Leigh Dodds > Programme Manager, Talis Platform > Talis > leigh.dodds@talis.com > http://www.talis.com > >
Received on Tuesday, 6 April 2010 23:14:52 UTC