[Crm-sig] CRM in Linked Data

martin martin at ics.forth.gr
Fri Mar 5 20:10:50 EET 2010


Thank you all,

We'll make a new demo soon.

Best,

Martin

Thomas Baker wrote:
> Hi Martin,
> 
> On Fri, Mar 05, 2010 at 06:01:18PM +0200, Martin Doerr wrote:
>> Here a test how CRM concepts could be published as Linked open Data.
>>
>> http://www.cidoc-crm.org/crm-concepts#E34 etc.
>>
>> The idea is, that the concept E34 is meant by "http://www.cidoc-crm.org/crm-concepts#E34",
>> and not the document fragment.
> 
> If the hash part is actually an anchor in an HTML file (i.e.
> document fragment), it is hard to argue that it also stands for
> a concept.
> 
> An alternative approach is to use the base URI for a document 
> and use the hash part to prolong that URI into an identifier for
> a concept.  For example, try clicking on:
> 
>     http://id.loc.gov/authorities/sh85014152#concept
>     http://id.loc.gov/authorities/sh85014152
> 
> The first is the identifier for the concept "Biography", so you
> would use that whenever you want to reference the concept.
> However, clicking on the first takes you to the second, which is
> a reference to a Web page containing a description of the concept.
> 
> In my understanding, OAI-ORE uses this approach to distinguish a
> Resource Map (documentation) from an Aggregation (as a
> conceptual entity) [1].
> 
> [1] http://www.openarchives.org/ore/1.0/primer#remHashURIs
> 
>> Should we better call it "http://www.cidoc-crm.org/crm-concepts/E34", raise an http 303 error
>> and then redirect to http://www.cidoc-crm.org/crm-concepts#E34 ?
> 
> That is another valid approach.
> 
>> Also completely unclear to me, how the Semantic Web community would recommend to have
>> a persistent concept URI across multiple RDFS file versions.
> 
> DCMI (and some other vocabularies) use separate sets of URIs for the concepts
> and for the documents.  For example, [1] for the concept dc:title and [2] for 
> the latest RDF file where dc:title is defined.  If you see for yourself with
> 
>     curl -I http://purl.org/dc/elements/1.1/title
> 
> it will tell you:
> 
>     HTTP/1.1 302 Moved Temporarily
>     Date: Fri, 05 Mar 2010 17:32:13 GMT
>     Server: 1060 NetKernel v3.3 - Powered by Jetty
>     Location: http://dublincore.org/2008/01/14/dcelements.rdf#title
>     Content-Type: text/html; charset=iso-8859-1
>     X-Purl: 2.0; http://localhost:8080
>     Expires: Thu, 01 Jan 1970 00:00:00 GMT
>     Content-Length: 286
> 
> This is actually not best practice because we set up these redirects
> before OCLC hired Zepheira to re-implement the purl software to support
> 303 response codes (which are more correct). It is on our list to correct
> the response codes returned by these purls.
> 
> Whenever we issue a new version of the RDF schema (e.g., with editorial
> changes or additions), we log into the PURL server and change the PURLs
> to redirect to the new file.
> 
> [1] http://purl.org/dc/elements/1.1/title
> [2] http://dublincore.org/2008/01/14/dcelements.rdf
> 
> For another approach, see how BBC has done it [1,2,3,4].
> 
> [1] http://www.bbc.co.uk/music/artists/a3cb23fc-acd3-4ce0-8f36-1e5aa6a18432
> [2] http://www.bbc.co.uk/music/artists/a3cb23fc-acd3-4ce0-8f36-1e5aa6a18432#artist
> [3] http://www.bbc.co.uk/music/artists/a3cb23fc-acd3-4ce0-8f36-1e5aa6a18432.html
> [4] http://www.bbc.co.uk/music/artists/a3cb23fc-acd3-4ce0-8f36-1e5aa6a18432.rdf
> 
> The current documents describing the 303 redirect approach are [1]
> and [2], but the RDFa approach used (redundantly) by Library of Congress
> is gaining traction  (e.g., view the page source for [3]).
> 
> [1] http://www.w3.org/TR/swbp-vocab-pub/ 
> [2] http://www.w3.org/TR/cooluris/
> [3] http://id.loc.gov/authorities/sh85014152#concept
> 
> As of two years ago, we believed that "slash" URIs provided more
> flexibility for large-scale vocabularies and "hash" URIs were
> simpler for vocabularies that fit easily into a small file that
> could be downloaded without using alot of bandwidth.
> 
> But as these different methods are deployed, our collective
> understanding of the design tradeoffs is improving.
> 
> The best place to ask this question is on the mailing list
> pedantic-web [1].  I also follow that list and will be eager to
> hear what the people there currently have to say.
> 
> Tom
> 
> [1] http://groups.google.com/group/pedantic-web
> 


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