RDF document?

Thanks for the correction of the term "document". It is an important concept 
of RDF.

Consider the property foaf:workplaceHomepage [1], the domain of this 
property is the class foaf:Document. Let's see the example..

<foaf:Person>
 <foaf:name>Dan Brickley</foaf:name>
 <foaf:workplaceHomepage rdf:resource="http://www.w3.org/"/>
</foaf:Person>

I always think that this example is misleading. I would prefer to put the 
above example in the following way..

<foaf:Person>
<foaf:name>Dan Brickley</foaf:name>
<foaf:workplaceHomepage 
rdf:datatype="http://www.w3.org/2001/XMLSchema#anyURI">http://www.w3.org/</foaf:workplaceHomepage>
</foaf:Person>


Regards,
Jeremy Wong 黃泓量

[1] http://xmlns.com/foaf/0.1/#term_workplaceHomepage

----- Original Message ----- 
From: "Frank Manola" <fmanola@acm.org>
To: "Jeremy Wong 黃泓量" <jeremy@miko.hk>
Cc: "Chris Purcell" <cjp39@cam.ac.uk>; <semantic-web@w3.org>
Sent: Wednesday, June 08, 2005 1:41 AM
Subject: Re: URI ends with #


> Section 0.1 of RDF Semantics says:  "There are several aspects of
> meaning in RDF which are ignored by this semantics; in particular, it
> treats URI references as simple names, ignoring aspects of meaning
> encoded in particular URI forms [RFC 2396] and does not provide any
> analysis of time-varying data or of changes to URI references. It does
> not provide any analysis of indexical uses of URI references, for
> example to mean 'this document'."
>
> Section 1.2 goes on to say: "The semantics does not assume any
> particular relationship between the denotation of a URI reference and a
> document or Web resource which can be retrieved by using that URI
> reference in an HTTP transfer protocol, or any entity which is
> considered to be the source of such documents. Such a requirement could
> be added as a semantic extension, but the formal semantics described
> here makes no assumptions about any connection between the denotations
> of URI references and the uses of those URI references in other 
> protocols."
>
> IOW, RDF doesn't associate any special meanings with various URI forms,
> including those with empty fragids.  They are simply names, to be
> compared as strings (as noted already). RDF, strictly speaking, doesn't
> really include the concept of a "document" per se;  the closest thing is
> a "graph".  I think phrases like "RDF document" in various specs should
> be understood as meaning "some document that contains RDF statements"
> (such as an RDF/XML document;  since RDF/XML is XML, it's legitimate to
> talk about "documents" in this case, since XML formally defines what a
> "document" is).  The RDF Concepts material referred to here doesn't say
> that there *are* "RDF documents" corresponding to the URIrefs it's
> talking about;  it says you can reconcile the RDF and RFC 2396 uses of
> fragids by imagining that there such documents.
>
> --Frank
>
> Jeremy Wong 黃泓量 wrote:
>>
>> "Two RDF URI references are equal if and only if they compare as equal,
>> character by character, as Unicode strings" [1]
>>
>> It is actually a Simple String Comparison [2].
>>
>> Another point is that, the meaning of a fragment is scheme dependent.
>>
>> I don't know whether an empty fragid reference the entire document 
>> either.
>>
>>
>>
>> Regards,
>> Jeremy Wong 黃泓量
>>
>>
>> -- 
>> [1] 
>> http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#dfn-URI-reference
>> [2] RFC3986, Section 6.2.1.  Simple String Comparison
>>
>>
>> ----- Original Message ----- From: "Chris Purcell" <cjp39@cam.ac.uk>
>> To: "Jeremy Wong 黃泓量" <jeremy@miko.hk>
>> Cc: <semantic-web@w3.org>
>> Sent: Tuesday, June 07, 2005 8:05 PM
>> Subject: Re: URI ends with #
>>
>>
>>> Does an empty fragid reference the entire document? That would mean
>>> <http://www.example.org/#> is the same URI as <http://www.example.org/>.
>>>
>>> Chris
>>>
>>>> Thanks Arjohn,
>>>>
>>>> I am actually writing a serializer that put me into the question. I
>>>> am sure that I should throw an exception for this case and those
>>>> cases mentioned in the Serialising section.
>>>>
>>>>
>>>> Regards,
>>>> Jeremy Wong 黃泓量
>>>>
>>>>>> Consider the rdf:Property http://example.org/#
>>>>>>  in Notation 3, I can write a triple as
>>>>>> <http://example.org/A> <http://example.org/#> <http://example.org/B> 
>>>>>> .
>>>>>>  in RDF/XML, how can I write the triple? Let me try...
>>>>>>  <Description xmlns:ex="http://example.org/#"
>>>>>> rdf:about="http://example.org/A">
>>>>>>   <ex: rdf:resource="http://example.org/B" />
>>>>>> </Description>
>>>>>>  However, "ex:" does not match the definition of Qualified Names
>>>>>> [1] and the character "#" is not an NCNameChar [2]. I don't have
>>>>>> any idea to express the predicate which its URI ends with #. Any
>>>>>> suggestion?
>>>>>
>>>>>
>>>>> This triple cannot be serialized in RDF/XML. See [1] for a short
>>>>> discussion on the serialization of RDF in XML. The only way to
>>>>> serialize
>>>>> such a triple is to use one of the other formats (N3, Turtle, ...).
>>>>>
>>>>> Arjohn
>>>>>
>>>>> [1] http://www.w3.org/TR/rdf-syntax-grammar/#section-Serialising
>>>
>>>
>>>
>>
>>
>>
>>
>

Received on Thursday, 9 June 2005 01:36:13 UTC