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Re: Dataset URIs and metadata.

From: Michael Hausenblas <michael.hausenblas@deri.org>
Date: Fri, 22 Jul 2011 11:41:47 +0100
Cc: public-lod@w3.org
Message-Id: <81EE350F-F348-4346-9CD3-43C7A15F98D5@deri.org>
To: Frans Knibbe <frans.knibbe@geodan.nl>


> So, does this mean that the URI of the dataset (DBPedia) is http://lod-cloud.net/dbpedia? 
> ?

It is one URI identifying the DBpedia dataset, yes. It is likely not  
the authoritative one as it is not int the dbpedia.org namespace, so  
there may be others ...

Cheers,
	Michael
--
Dr. Michael Hausenblas, Research Fellow
LiDRC - Linked Data Research Centre
DERI - Digital Enterprise Research Institute
NUIG - National University of Ireland, Galway
Ireland, Europe
Tel. +353 91 495730
http://linkeddata.deri.ie/
http://sw-app.org/about.html

On 22 Jul 2011, at 11:16, Frans Knibbe wrote:

> Hello Michael,
>
> On 2011-07-22 10:59, Michael Hausenblas wrote:
>>
>> Frans,
>>
>>> I had a quick look. But I could not find it. I had a closer look  
>>> now and I see the URI probably is http://dbpedia.org/void/Dataset.  
>>> I have tried it. Redirection to either HTML or RDF seems to be in  
>>> place. HTML request lead to http://dbpedia.org/void/page/Dataset,  
>>> which shows a table of VoID properties. The RDF redirection (to http://dbpedia.org/void/data/Dataset.rdf) 
>>>  does not seem to work, I get an error.
>>
>> Sorry, you lost me here. Did you curl it or how did you get your  
>> findings?
>
> Yes, I tried curl. I have just tried it again:
>
> curl -H "Accept: application/rdf+xml" http://dbpedia.org/void/data/Dataset.rdf
>
> The response seems to be different from yesterday. Yesterday I  
> immediately got an error message. I am afraid I don't have the exact  
> message any more. The response I get now is different, a transaction  
> time out, which I get after waiting a bit.
>
> Probably this is just a temporary situation and besides the point too.
>>
>>> Apart from the error, somehow this is not what I expected. I  
>>> assumed that the dataset URI is the URI of a dataset. It is the  
>>> key to all other data. If you want something from a dataset, you  
>>> only need to know this URI. So why is the dataset URI hard to  
>>> find? Why isn't it used when references are made to DBpedia? Why  
>>> isn't it the same as the base URI (http://dbpedia.org)?.
>>
>> <http://lod-cloud.net/dbpedia> a void:Dataset;
>>                               foaf:homepage <http://dbpedia.org/>;
>>
>> Says everything, or?
> Well, let me see...
>
> First of all, please know that I am new to Linked Data and RDF, so  
> there is a chance I don't fully understand everything.
>
> I think what it says is that there is a thing identified by the URI http://lod-cloud.net/dbpedia 
> , that that thing is a dataset and that its home page is http://dbpedia.org/ 
> .
>
> So, does this mean that the URI of the dataset (DBPedia) is http://lod-cloud.net/dbpedia? 
> ?
>
> Sorry if I seem to be stupid, it is not my intention.
>
>>
>>> Probably VoID metadata/dataset URIs will be easier to discover  
>>> once the /.well-known/void trick (described in paragraph 7.2 of  
>>> the W3C VoID document) is widely adopted.
>>
>> Agreed. But it's not a 'trick'. It's called a standard.
> Sorry about that!
>
> Regards,
> Frans
>>
>> Cheers,
>>    Michael
>> -- 
>> Dr. Michael Hausenblas, Research Fellow
>> LiDRC - Linked Data Research Centre
>> DERI - Digital Enterprise Research Institute
>> NUIG - National University of Ireland, Galway
>> Ireland, Europe
>> Tel. +353 91 495730
>> http://linkeddata.deri.ie/
>> http://sw-app.org/about.html
>>
>> On 22 Jul 2011, at 09:42, Frans Knibbe wrote:
>>
>>> On 2011-07-21 16:27, Michael Hausenblas wrote:
>>>>
>>>>
>>>>> But is this really common practice nowadays? Take DBpedia for  
>>>>> example. What is the URI of the DBpedia dataset? Is it http://dbpedia.org? 
>>>>>  That does not seem to resolve to a set of metadata.
>>>>
>>>> Did you have a look at the URI I gave you? I mean http://lod-cloud.net/void.ttl
>>> I had a quick look. But I could not find it. I had a closer look  
>>> now and I see the URI probably is http://dbpedia.org/void/Dataset.  
>>> I have tried it. Redirection to either HTML or RDF seems to be in  
>>> place. HTML request lead to http://dbpedia.org/void/page/Dataset,  
>>> which shows a table of VoID properties. The RDF redirection (to http://dbpedia.org/void/data/Dataset.rdf) 
>>>  does not seem to work, I get an error.
>>>
>>> Apart from the error, somehow this is not what I expected. I  
>>> assumed that the dataset URI is the URI of a dataset. It is the  
>>> key to all other data. If you want something from a dataset, you  
>>> only need to know this URI. So why is the dataset URI hard to  
>>> find? Why isn't it used when references are made to DBpedia? Why  
>>> isn't it the same as the base URI (http://dbpedia.org)?.
>>>
>>> Probably VoID metadata/dataset URIs will be easier to discover  
>>> once the /.well-known/void trick (described in paragraph 7.2 of  
>>> the W3C VoID document) is widely adopted.
>>>
>>>>
>>>> BTW, some 30% [1] of the LOD cloud datasets are using VoID ...
>>>>
>>>>> Is there a general way of obtaining datasets URIs?
>>>>
>>>> Not to my knowledge. We're working on it in LATC [2] - Keith?
>>>>
>>>> Cheers,
>>>>    Michael
>>>>
>>>> [1] http://www4.wiwiss.fu-berlin.de/lodcloud/state/#data-set-level-metadata
>>>> [2] http://latc-project.eu/
>>>>
>>>> -- 
>>>> Dr. Michael Hausenblas, Research Fellow
>>>> LiDRC - Linked Data Research Centre
>>>> DERI - Digital Enterprise Research Institute
>>>> NUIG - National University of Ireland, Galway
>>>> Ireland, Europe
>>>> Tel. +353 91 495730
>>>> http://linkeddata.deri.ie/
>>>> http://sw-app.org/about.html
>>>>
>>>> On 21 Jul 2011, at 15:19, Frans Knibbe wrote:
>>>>
>>>>>
>>>>> Thanks for the replies. It seems that there is agreement that a  
>>>>> dataset should have a URI and that dereferencing that URI should  
>>>>> return metadata about the dataset. That is good to know.
>>>>>
>>>>> But is this really common practice nowadays? Take DBpedia for  
>>>>> example. What is the URI of the DBpedia dataset? Is it http://dbpedia.org? 
>>>>>  That does not seem to resolve to a set of metadata.
>>>>>
>>>>> Is there a general way of obtaining datasets URIs?
>>>>>
>>>>> I can imagine an RDF dataset comprising all known dataset URIs.  
>>>>> And of course that dataset will have a URI itself. Does such a  
>>>>> dataset exist at the moment?
>>>>>
>>>>> Regards,
>>>>> Frans
>>>>>
>>>>>
>>>>> On 2011-07-21 12:35, Frans Knibbe wrote:
>>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> I have just placed a Linked Data dataset online and now I am  
>>>>>> struggling with finding the best way to publish the metadata of  
>>>>>> the dataset. I wonder if there are best practices for  
>>>>>> referencing a dataset and its metadata, and for linking the two.
>>>>>>
>>>>>> I did find out that using the Vocabulary of Interlinked Data  
>>>>>> (VoID) is a good way to publish the metadata of a dataset. But  
>>>>>> I still need some guidance. I have come up with three questions:
>>>>>>
>>>>>> 1) Is it common practice/recommendable to regard a dataset a  
>>>>>> resource? If it is, then all datasets should have a URI, right?
>>>>>> 2) If having a dataset URI is a good thing, what should be  
>>>>>> behind the URI? Should dereferencing the URI lead to the  
>>>>>> dataset metadata (a VoID file for example)?
>>>>>> 3) If dereferencing a dataset  URI leads to the dataset  
>>>>>> metadata, should there be separate HTML and RDF versions of the  
>>>>>> metadata? Or is it better to have a HTML page with embedded  
>>>>>> (RDFa) RDF data?
>>>>>>
>>>>>> Thanks in advance for your help,
>>>>>> Frans
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
>
>
Received on Friday, 22 July 2011 10:42:32 UTC

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