- From: Karen Coyle <kcoyle@kcoyle.net>
- Date: Thu, 25 Aug 2011 15:53:20 -0700
- To: public-xg-lld@w3.org
Quoting "Young,Jeff (OR)" <jyoung@oclc.org>: > I'm uncomfortable using the term AP even for situations where a variety > of existing classes and properties are getting reused. An OWL ontology > can be created to document this situation, even if no new terms are > being defined there. I agree with Jeff here. It seems that AP is being used for any ontology that uses a mix of namespaces or that adopts properties from existing namespaces. This seems to me to be normal practice for ontology development. At what point does a choice of properties become an AP? In DC terms, I think that it becomes an AP only when constraints are added (mandatory, optional, repeatable or not, etc.). I commonly hear people use the term AP when someone consciously creates a personalized or modified version of a known metadata schema. So a sub-set of, say, MARC that selects out the fields needed to encode music resources but not cartographic resources would be an AP in this definition. Basically, I think we don't have a clear enough definition of AP to use the term in this report without going through a lengthy discussion that would allow us to make it clear. I'd prefer to leave it out, but think that the concept is important and definitely needs more thought. kc > Granted, you don't see much of that happening yet, > but presumably that's presumably because people are still trying to wrap > their minds around OWL in general. > >> But there are many situations in which re-using a >> vocabulary comes with risks/costs that could motivate coining one's > own >> "duplicate" elements. Consider what schema.org did: they just prefered >> to coin all the elements they need, rather than spend time shopping >> around for existing elements--which may be not well maintained anyway. >> That's maybe not the best practice around, but that will continue to >> happen. In such cases, establishing alignments between element sets is >> a lesser evil. > > As a species, I think we are still beginners in terms of modular > thinking. I can't think of a single existing model or set of models that > doesn't make me squirm and shake. "Alignments" or "mappings" give me > hope that we will be able to adapt regardless. > >> >> The "gradient" of best practice here would be: (1) own duplicate >> element sets with no alignment; (2) own element sets with alignment to >> existing vocabularies (3) "true" APs with re-use of existing >> vocabularies. > > I agree with these idealized gradients with a couple of caveats. > > 1) Existing vocabularies that don't conform to best practice recipes > suck: http://www.w3.org/TR/swbp-vocab-pub/ > 2) Some existing vocabularies (even popular ones) can be very weird and > arguably would be better off being mapped > 3) The ability to transform domain-specific vocabularies into foreign > vocabularies shouldn't be that far off if the mappings exist > >> >> I'm not saying that it was clearly worded here, far from it :-) >> I can also live with this point being mentioned in another section. > But >> I wanted to warn against making this disappear, altogether. > > I suspect that all these thoughts are too controversial to used on short > notice, though. > > Jeff > >> >> Cheers, >> >> Antoine >> >> > Dear all, >> > >> > Re-reading the paragraph in [1]: >> > >> > A similar concern can be voiced regarding metadata element > sets. >> As >> > testified in the Linked Open Vocabularies inventory, >> practitioners >> > generally follow the good practice of re-using existing element >> sets or >> > building "application profiles" of them. And some projects, > such >> as the >> > Vocabulary Mapping Framework, aim at supporting that process. >> But the lack >> > of long-term support for them threatens their enduring meaning >> and common >> > understanding. Further, some reference frameworks, notably > FRBR, >> have been >> > implemented in different RDF vocabularies, which are not always >> connected >> > together. Such situation lowers the semantic interoperability > of >> the >> > datasets expressed using these RDF vocabularies. The community >> should >> > encourage the coordinated re-use of element sets for particular >> entity >> > descriptions, their extension through, e.g., application >> profiles, or their >> > alignment using, e.g., semantic relations from RDFS and OWL. >> Here, we hope >> > that better communication between the creators and maintainers >> of these >> > resources, as encouraged by our own incubator group or the LOD- >> LAM >> > initiative, will help to consolidate the conceptual connections >> between >> > them. >> > >> > ...where "a similar concern" refers to "semantic links across value >> vocabularies". >> > >> > Looking closer: >> > >> >> A similar concern can be voiced regarding metadata element sets. As >> >> testified in the Linked Open Vocabularies inventory, practitioners >> >> generally follow the good practice of re-using existing element > sets >> or >> >> building "application profiles" of them. >> > >> > If we mean Dublin-Core-style application profiles (as Singapore >> Framework is >> > cited further on in the paragraph), then we could say something > like: >> > >> > A similar concern can be voiced regarding metadata element >> sets. As >> > testified in the Linked Open Vocabularies inventory, >> practitioners >> > generally follow the good practice of re-using existing > element >> sets or >> > building "application profiles" that re-use elements from >> multiple sets. >> > >> > Then, I do not really understand the first part of this sentence: >> > >> >> The community should encourage the coordinated re-use of element >> sets for >> >> particular entity descriptions, their extension through, e.g., >> application >> >> profiles, or their alignment using, e.g., semantic relations from >> RDFS and >> >> OWL. >> > >> > The phrase "encourage the coordinated re-use of element sets for >> > particular entity descriptions" seems to be saying something like: >> > >> > ...promote the use of common patterns of mixing vocabularies > for >> > describing particular types of things. >> > >> > However, I do not think this reference to application profiles > really >> belongs >> > in a section on alignment. >> > >> > Rather, I would like to propose the following: >> > >> > -- That the section "The linking issue" (vague, because the whole > LLD >> XG report is >> > arguably about a "linking issue") be renamed something like: >> > >> > Semantic alignment >> > >> > -- In this case, the first sentence -- "Many semantic links across >> value >> > vocabularies are already available..." -- could be preceded with >> a definition >> > along the lines of: >> > >> > "Alignments" are links between semantically equivalent, >> similar, or >> > related terms or entities across different value >> vocabularies, metadata >> > element sets, or datasets. >> > >> > -- The notion of application profiles is more appropriately >> referenced in the point >> > about re-using patterns: >> > >> > In the paragraph: >> > >> > Design patterns allow implementers to build on the experience > of >> > predecessors. Traditional cataloging practices are documented >> with a rich >> > array of patterns and examples, and best practices are starting >> to be >> > documented for the Linked Data space as a whole (e.g., >> > <ref>http://linkeddatabook.com/editions/1.0/#htoc61</ref>). [*] >> What is needed >> > are design patterns specifically tailored to LLD requirements. >> Such design >> > patterns would meet the needs of people and developers who >> understand new >> > techniques through patterns and examples and will increase the >> coherence of >> > Library Linked Data overall. >> > >> > I propose inserting a sentence: >> > >> > Application profiles > (http://dublincore.org/documents/singapore- >> framework/) >> > provide a method for a community of practice to document and >> share patterns >> > used for describing specific types of materials. >> > >> > -- ...and application profiles are also relevant to "data design" >> [2]: >> > >> > Another boost for Linked Data is the growing use of OWL for >> purposes of >> > data design. Prior to OWL, domain experts could use RDFS to >> create metadata >> > element sets, but there was no way to map equivalencies across >> > vocabularies. Among other features, OWL includes an upgrade to >> RDFS to >> > support ontology mapping. This allows experts to describe their >> domain >> > using community idioms, while still being interoperable with >> related or >> > more common idioms. A variety of tools related to OWL can be >> found on the >> > W3C's RDF wiki and OWL wiki. Unified Modeling Language (UML) >> tools are also >> > value to help designers represent and manipulate domain models >> visually. >> > The Ontology Definition Metamodel (ODM) specification should >> help bridge >> > some of the gaps between UML and OWL. [*] >> > >> > I propose to add: >> > >> > Application profiles > (http://dublincore.org/documents/singapore- >> framework/) >> > provide a way to specify how a community of practice defines a >> > domain model and re-uses specific vocabularies in order to >> create metadata >> > conforming to a particular pattern. >> > >> > Tom >> > >> > [1] >> > http://www.w3.org/2005/Incubator/lld/wiki/DraftReportWithTransclusion#T >> he_linking_issue >> > [2] >> > http://www.w3.org/2005/Incubator/lld/wiki/DraftReportWithTransclusion#T >> ools_for_data_designers >> > [3] >> > http://www.w3.org/2005/Incubator/lld/wiki/DraftReportWithTransclusion#D >> evelop_and_disseminate_best-practices_design_patterns_tailored_to_LLD >> > >> > >> >> > > > > -- Karen Coyle kcoyle@kcoyle.net http://kcoyle.net ph: 1-510-540-7596 m: 1-510-435-8234 skype: kcoylenet
Received on Thursday, 25 August 2011 22:53:49 UTC