purl, vocabularies and ivoa.net

Mon Sep 25 11:33:31 CEST 2017

Dear semantics and theory,

Thank you very much for your feedbacks about our proposition of a way to 
put theory vocabularies in the IVOA.

We would like to conclude on this topic.

In the discussions, two aspects have been mixed
1) the need to have URL on IVOA website to store vocabulary files (datalink, theory, etc …)
2) the need to have URI to define concepts.

Below we summarise the two points and propose solutions considering the discussions on the mailing list.

1. Storage of vocabulary files on the IVOA website
----------

That is where (and in which format) to store the vocabularies. The proposition from Mireille seems good, in addition it uses existing IVOA convention.

So, storing a representation of our vocabulary (say a rdf file) in ivoa.net/vocabularies/theory/skos/TheoryVocabulary-1.0-20160101.rdf
is fine.

If we were to add another representation format, we would just have to add it under a relevant segment instead of SKOS, for example JSON, XML or whatever.

2. Unique Identifiers
--------------

We need to identify the concepts in our vocabulary.  To do so we would like to use URIs as ID. The nice thing about doing that is we can associate a representation (ex a SKOS XML subset, an HTML page, a .txt file, ...) with an ID (in this case an URI), which can change over time, while the ID remains unchanged.

Since these URIs will be identifiers we want them to be permanent and unique. Then we need a namespace in ivoa.net where to define permanent URIs, to be used as identifiers.

Adding a 'purl' segment to a path rooted inwww.ivoa.net  could be used, sure, the problem is that www carries representation semantic with it, that is HTML. We don't want the identifiers to be coupled with representation details, such as HTML, or SKOS, rdf or whatever. The 'purl' subdomain doesn’t carry much semantic with it and seems a perfect abstract place (namespace) where to define permanent URIs to be used as identifiers, IDs.

So we propose: purl.ivoa.net/theory/ConceptName<http://purl.ivoa.net/theory/ConceptName>

Best regards.

Nicolas Moreau

Le 01/06/2017 à 10:03, Gray, Alasdair J G a écrit :
> Hi
>
> I completely agree with the idea of having a high-level directory like 
> vocabularies. However, after that should we not use content 
> negotiation to request the specific format that we are interested. The 
> metadata about the vocabulary (reproduced in a human readable form on 
> the HTML page), could inform clients what formats are available.
>
> Best regards,
>
> Alasdair
>
>> On 31 May 2017, at 23:18, Mireille Louys <mireille.louys at unistra.fr 
>> <mailto:mireille.louys at unistra.fr>> wrote:
>>
>> Hi Marco ,
>>
>> Thanks for summarising this issue.
>> There is also a need to discover more easily where to find the 
>> various vocabularies proposed by the Ivoa .
>> I would appreciate to have a link from the IVOA document repository 
>> page directly , to a IVOA Vocabulary page like what we have for XML 
>> schemata, for instance.
>>
>> Various vocabularies already exist , in various formats and are used 
>> in DAL( datalink, RDF, html), Registry (VOResource litterals, CSV), 
>> Theory ( theoryvocabulary RDF/SKOS )
>> So this page would actually redistribute the link access to the 
>> corresponding locations .
>> Each of these vocabularies should be maintained in close contact to 
>> their WG and users , and I see the role of Semantics more as a 
>> coordinator and curator for the long term.
>>
>> How to organize the vocabulary tree , is still to be decided .
>> ivoa.net/rdf <http://ivoa.net/rdf> does not mean every file in this 
>> directory should be in rdf format but this is somewhat misleading.
>> In order to allow to gather all representation formats for some 
>> particular vocabulary, I would prefer to have one branch for each 
>> vocabulary and the various formats below like :
>> ivoa.net/vocabularies/datalink/rdf/datalink-1.0-20151107.rdf 
>> <http://ivoa.net/vocabularies/datalink/rdf/datalink-1.0-20151107.rdf>
>> ivoa.net/vocabularies/datalink/csv/datalink-1.0-20151107.txt 
>> <http://ivoa.net/vocabularies/datalink/csv/datalink-1.0-20151107.txt>
>> ...
>> ivoa.net/vocabularies/theory/skos/vocabForTheory-1.0-20160101.rdf 
>> <http://ivoa.net/vocabularies/theory/skos/vocabForTheory-1.0-20160101.rdf>
>> ivoa.net/vocabularies/theory/skos/vocabForTheory-1.0-20170509.rdf 
>> <http://ivoa.net/vocabularies/theory/skos/vocabForTheory-1.0-20170509.rdf>
>> etc...
>> and the same for registry vocabularies if needed.
>> Each of them could be redirected to another site as purl.obspm.fr 
>> <http://purl.obspm.fr> or anyother.
>>
>> If the curator of the vocabulary is close enough to the users , this 
>> should work, or am I overlooking some issue here?
>>
>> my 2c for the moment,
>>
>> cheers, Mireille
>>
>>
>>
>> Le 19/05/2017 à 08:42, Marco Molinaro a écrit :
>>> Dear Semantics,
>>> Dear Theory,
>>> (IVOADoc in CC)
>>>
>>> during the session this Tuesday, in the "SKOS in VO THeory" talk, it
>>> was proposed a change for the vocabulary for Theory VO with patterns
>>> pointing to
>>>
>>> http://purl.ivoa.net/ConceptName
>>>
>>> Now (apart from DNS aspects that can be managed on the DNS+IVOADoc
>>> side - that's why IVOADoc is in CC),ivoa.net <http://ivoa.net>  has already a branch
>>>
>>> http://www.ivoa.net/rdf/
>>>
>>> that is meant to store vocabularies (Datalink one is already there).
>>> Also, the theory vocabulary will actually physically be in Paris, i.e.
>>> purl.ivoa.net <http://purl.ivoa.net>  will simply redirect to it.
>>>
>>> This email is to try to understand exactly how we can make this things
>>> work together, namely:
>>> - thepurl.ivoa.net <http://purl.ivoa.net>  and its redirection to Paris (but possibly it
>>> should survive inivoa.net <http://ivoa.net>  and be used by other parties)
>>> - the relationship betweenpurl.ivoa.net <http://purl.ivoa.net>  andwww.ivoa.net/rdf
>>>
>>> Ideas, comments, .... are welcome, so that we can also start thinking
>>> of DNS changes in Trieste (hosting theIVOA.net <http://ivoa.net>  domain and related
>>> DNS) and maybe in IUCAA (where the web part of theivoa.net <http://ivoa.net>  is
>>> physically located.
>>> I can take care of connecting with IVOADoc andivoa.net <http://ivoa.net>  sysadmins for
>>> the technical part.
>>>
>>> Cheers,
>>>      Marco
>>
>> -- 
>> --
>> Mireille Louys
>> CDS  						Laboratoire Icube
>> Observatoire de Strasbourg	Telecom Physique Strasbourg
>> 11 rue de l'Université 		300, Bd Sebastien Brandt CS 10413 		
>> F- 67000-STRASBOURG			F-67412 ILLKIRCH Cedex
>> tel: +33 3 68 85 24 34
>
> Alasdair J G Gray
> Fellow of the Higher Education Academy
> Assistant Professor in Computer Science,
> School of Mathematical and Computer Sciences
> (Athena SWAN Bronze Award)
> Heriot-Watt University, Edinburgh UK.
>
> Email: A.J.G.Gray at hw.ac.uk <mailto:A.J.G.Gray at hw.ac.uk>
> Web: http://www.macs.hw.ac.uk/~ajg33 <http://www.macs.hw.ac.uk/%7Eajg33>
> ORCID: http://orcid.org/0000-0002-5711-4872
> Office: Earl Mountbatten Building 1.39
> Twitter: @gray_alasdair
>

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