W3C home > Mailing lists > Public > public-lod@w3.org > December 2009

Re: Contd: [pedantic-web] question about sioc / foaf usage

From: Nathan <nathan@webr3.org>
Date: Tue, 01 Dec 2009 22:37:57 +0000
Message-ID: <4B159AC5.5080207@webr3.org>
To: Kingsley Idehen <kidehen@openlinksw.com>
CC: Linked Data community <public-lod@w3.org>, pedantic-web@googlegroups.com, SIOC-Dev <sioc-dev@googlegroups.com>
Kingsley Idehen wrote:
> Nathan wrote:
>> Hi All,
>>
>> To follow on a conversation I'm having with Kingsley at the minute, and
>> to make it public, I'm also cc'ing in public-lod, pedantic-web and the
>> sioc user list, as it is to do with all 3. Please do give feedback and
>> correct me where I'm wrong. Especially if you can inline comment where
>> something is wrong in my understanding.
>>
>> Kingsley Idehen wrote:
>>  
>>> Nathan wrote:
>>>    
>>>> so do / should the Post, HTML Document and RDF Document all have
>>>> different Identifiers?
>>>>       
>>> If you want to make a statement (create a record) describing anything
>>> you need an Identifier for the subject of your description. If you want
>>> said description (a graph pictorial) to be fully explorable using HTTP
>>> (what Linked Data is about) then you shouldn't use the URL (Address of a
>>> Resource) as its Identifier. An HTTP GET against a URL has specific
>>> consequences distinct from an HTTP GET against a Generic HTTP scheme URI
>>> (a genuine Identifier/Name that Identifies an Object/Resource/Data
>>> Item/Entity).
>>>
>>> Rather than do the whole 303 and hash URI dance (counter productive
>>> since it dances around the issue of Data Identity), see if this document
>>> of Data Object Identity clarifies things for you re. Identifiers.
>>>
>>> Links:
>>>
>>> 1.
>>> http://www.cs.cmu.edu/afs/cs.cmu.edu/user/clamen/OODBMS/Manifesto/htManifesto/node4.html
>>>
>>>
>>>     
>>
>> okay.. here's the set-up; I have:
>>
>> * a "Post" which is a <sioc:Post>
>> * a HTML Document which contains (among other things) a human readable
>> representation of the <sioc:Post> at an URL
>> * a RDF Document which contains a graph pictorial of the <sioc:Post>
>> which is published at an URL
>>
>> to describe or reference the <sioc:Post> I have to give it a URI:
>>   <http://example.lod/uri/post-123>
>>
>> to describe or reference the HTML Document I have to give it a URI:
>>   <http://example.lod/uri/html-document-123>
>> in addition the HTML document has an URL
>>   <http://example.lod/documents/html-document-123.html>
>>
>> to describe or reference the RDF Document I have to give it a URI:
>>   <http://example.lod/uri/rdf-graph-123>
>> in addition the RDF document has an URL
>>   <http://example.lod/documents/rdf-document-123.rdf>
> Assumption: your Identifiers are slash terminated (i.e. Slash style of
> Generic HTTP URI).
>>
>> now, I'm assuming the RDF Document will need to be self describing (also
>> contain a graph pictorial about itself, as well as the <sioc:Post> -
>> here's a very simplified version of the triples it'd contain.
>>   
> So the RDF data container (resource)  is:
> 
> <http://example.lod/documents/rdf-document-123.rdf>, right?
> 
>>   <http://example.lod/uri/rdf-graph-123> <rdf:type> <foaf:Document> ;
>>     <dc:title> "SIOC Post profile for post-123"@en
>>     <foaf:primaryTopic> <http://example.lod/uri/post-123> .
>>
>>   <http://example.lod/uri/post-123> <rdf:type> <sioc:Post> .
>>
>> Q1: is <foaf:primaryTopic> correct here?
>>   
> Yep.
>> to say that the <sioc:Post> is contained by this graph we'd add the
>> triple:
>>   <http://example.lod/uri/post-123>
>>     <sioc:link> <http://example.lod/uri/rdf-graph-123> .
>>   
> Redundant, but not necessarily incorrect. You can make redundant
> statements :-)
>> then we need to say where the rdf graph can be found (provide it's URL):
>>   <http://example.lod/uri/rdf-graph-123>
>>     <??????> <http://example.lod/documents/rdf-document-123.rdf> .
>>   
> 
> <http://example.lod/documents/rdf-document-123.rdf> is a data set
> container so you identify it properly as in:
> <http://example.lod/documents/rdf-document-123.rdf#this>, via a simple
> URL to Generic HTTP URI hack, with Linked Data de-referencing in mind
> re. exploration of the description of this Thing/Object/Entity/Data
> Item. Note: a little change-up as I've added a new Identifier but taken
> the cheap # route via fragment identifier.
> 
> This also means your could have stated the following at the top:
> 
>  <http://example.lod/documents/rdf-document-123.rdf#this> <rdf:type>
> <foaf:Document> ;
>     <foaf:primaryTopic> <http://example.lod/uri/post-123> .
> 
>  <http://example.lod/uri/post-123> <rdf:type> <sioc:Post>;
>  <dc:title> "SIOC Post profile for post-123"@en.
> 
> OR even the following, assuming you'd already assigned these URIs and
> discovered that <http://example.lod/uri/rdf-graph-123> is basically the
> same as <http://example.lod/documents/rdf-document-123.rdf#this> i.e.,
> RDF data set containers (documents or information resources):
> 
>  <http://example.lod/documents/rdf-document-123.rdf#this> <rdf:type>
> <foaf:Document> ;
>        <owl:sameAs> <http://example.lod/uri/rdf-graph-123>;
>     <foaf:primaryTopic> <http://example.lod/uri/post-123> .
> 
>  <http://example.lod/uri/post-123> <rdf:type> <sioc:Post>;
>  <dc:title> "SIOC Post profile for post-123"@en.
> 
> 
> 
> 
>> Q2: which ontology does one use for <??????> in the above triple?
>>   
> None.
>> then we need to say that the HTML document is a document, that contains
>> a human readable version of the <sioc:Post> (amongst other things)
>>
>>   <http://example.lod/uri/html-document-123>
>>     <rdf:type> <foaf:Document> ;
>>     <foaf:primaryTopic> <http://example.lod/uri/post-123> .
>>
>> Q3: is the HTML Document a <sioc:Container>, which is a container of the
>> <sioc:Post>?
>>     <http://example.lod/uri/html-document-123>
>>     <rdf:type> <foaf:Document> , <sioc:Container> ;
>>     <foaf:primaryTopic> <http://example.lod/uri/post-123> ;
>>     <sioc:container_of> <http://example.lod/uri/post-123> .
>>   
> Yes, esp. as <sioc:Post> <rdfs:subClassOf> <sioc:Item> .
> 
> Note same applies to the RDF data container as in:
> 
> <http://example.lod/uri/rdf-graph-123> <rdf:type> <foaf:Document> ,
> <sioc:Container> ;
>     <foaf:primaryTopic> <http://example.lod/uri/post-123> ;
>     <sioc:container_of> <http://example.lod/uri/post-123> .
> 
> OR
> <http://example.lod/uri/rdf-graph-123> <rdf:type> <foaf:Document> ,
> <sioc:Container> ;
>        <owl:sameAs>
> <http://example.lod/documents/rdf-document-123.rdf#this>;
>     <foaf:primaryTopic> <http://example.lod/uri/post-123> ;
>     <sioc:container_of> <http://example.lod/uri/post-123> .
> 
> 
> 
>> Q4: should we also say the description of the HTML Document is also
>> contained by this graph?
>>   <http://example.lod/uri/post-123>
>>     <sioc:link> <http://example.lod/uri/rdf-graph-123> .
>>   
> 
> <http://example.lod/uri/rdf-graph-123> <sioc:link>
> <http://example.lod/uri/html-document-123>.
> or even: <http://example.lod/uri/rdf-graph-123> <foaf:Topic>
> <http://example.lod/uri/html-document-123>.
> 
> 
>> Q5: how do we specify the URL of the HTML Document?
>>     <http://example.lod/uri/html-document-123>
>>     <?????> <http://example.lod/documents/html-document-123.html> .
>>   
> Remember the earlier statement re. the RDF document (resource):
> 
> 
> <http://example.lod/documents/rdf-document-123.rdf#this> <rdf:type>
> <foaf:Document> ;
>        <owl:sameAs> <http://example.lod/uri/rdf-graph-123>;
>     <foaf:primaryTopic> <http://example.lod/uri/post-123> .
> 
> 
> Re. HTML resource description same thing applies re. association with
> the sioc:Post:
> 
>  <http://example.lod/documents/html-document-123.html#this> <rdf:type>
> <foaf:Document>;
>  <foaf:primaryTopic> <http://example.lod/uri/post-123> .
> 
>  <http://example.lod/uri/post-123> <rdf:type> <sioc:Post>;
>  <dc:title> "SIOC Post profile for post-123"@en.
> 
> OR
> 
> <http://example.lod/documents/html-document-123.html#this> <rdf:type>
> <foaf:Document> ;
>   <owl:sameAs> <http://example.lod/uri/html-document-123>;
>   <foaf:primaryTopic> <http://example.lod/uri/post-123> .
> 
> 
>  <http://example.lod/uri/post-123> <rdf:type> <sioc:Post>;
>  <dc:title> "SIOC Post profile for post-123"@en.
> 
> 
>> I think that's enough for now; all feedback welcome!
>>
>> regards
>>
>> nathan
>>
>>   
> Bar any typos or cut&paste snafus, I've hopefully answered your questions.
> Ultimately, the file (information resource, document, data container)
> has its own set of attributes e.g. format (dcterms:format), actual file
> name (not title of the content), creation date etc.. Distinct from the
> description of its content (hence the use of foaf:primaryTopic as
> conduit to content description graph).
> 
> Link:
> 
> 1.
> http://linkeddata.uriburner.com/about/html/http://news.cnet.com/8301-13577_3-10407056-36.html?tag=newsEditorsPicksArea.0
> - example of Linked Data graph that describes an document (information
> resource) in a manner distinct from its content (see the data exposed by
> foaf:primaryTopic) .
> 
> 

perfect, thanks kingsley :)

only q (which i still don't follow) is that afaik I *need* to specify in
 rdf where one can find the HTML document, no point describing something
people can't find... noted that in you're own rdf you use:
<resource>
<http://www.openlinksw.com/schema/attribution#isDescribedUsing> <url>

i essentially need the equiv for anything;

  <http://example.lod/uri/html-document-123>
	<canBeFound> <here/URL> .
or
	<has_link> <here/URL> .

the thing I'm describing can be found at web address, ie show the human
this version etc etc (if you follow)

regards,

nathan
Received on Tuesday, 1 December 2009 22:38:58 UTC

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