W3C home > Mailing lists > Public > semantic-web@w3.org > July 2006

Re: Semantic content negotiation (was Re: expectations of vocabulary)

From: Richard Newman <r.newman@reading.ac.uk>
Date: Sun, 30 Jul 2006 10:26:19 -0700
Message-Id: <2F3CE5AD-7FDD-435B-A5E8-A0F296B51126@reading.ac.uk>
Cc: "'Semantic Web'" <semantic-web@w3.org>
To: Xiaoshu Wang <wangxiao@musc.edu>

>>    I advise you to stop thinking in terms of documents; the
>> document model does not map well to the Semantic Web. It is
>> trivially easy to put some intelligence behind a URI, and I
>> have already illustrated two possible interpretations of
>> Accept-vocabulary that servers can provide, each of which
>> degrades well.
>
> Document model is for HTTP.  And we are talking about extending  
> HTTP, aren't
> we?

No -- HTTP returns *representations* of *resources*. Those  
representations don't have to be fixed documents; they can be  
dynamically composed, reflecting the client, various properties, or  
anything else that could make the representation better suited.

Rather, think of every request on the Semantic Web, even trivial  
GETs, as being implicitly a simple query -- "give me triples about  
this resource".

>>    "Write it in one version and indicate the mapping
>> ontologies". The work just happens to be done on the server
>> side, where it is more likely that the mappings are known and
>> a reasoner is available.
>
> What is your point? Isn't that what I was suggesting?

No. You were suggesting that the server provide the mapping  
information and the original data, and let the client sort it out.  
Accept-vocabulary allows the server to do that work if it can.

>>    I also expect a lot of data to be exposed from non-RDF
>> sources -- e.g., LDAP and relational databases. Choosing in
>> which vocabulary the information should be encoded is
>> something on which Accept-vocabulary can have a bearing, and
>> the information is not available in RDF to start with.
>
> Let's not make the problem strays again.  We are talking Accept- 
> Vocabulary
> in RDF, aren't we?

Where does the RDF come from? If you request a representation of a  
resource, and get RDF back, does it matter if it was generated on-the- 
fly from a database? This is exactly analogous to a HTML page  
generated by PHP from a database. My point is that it is trivial,  
with no ontology mapping needed, to put a switch into a *generated*  
page to produce vCard, FOAF, Norm Walsh's vocab, etc. on demand.
Received on Sunday, 30 July 2006 17:26:44 GMT

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