Re: comparing XML and RDF data models

What you really need is a language like mKR (http://mKRmKE.org/)
Given any thing, X, in a knowledge base

    X has ?;  # displays all attributes of X
    X do ? done;  # displays all actions of X
    X isc* ?;  # displays subhierarchy of X
    X isa* ?;  # displays all classes of X, up to Thing.

Dick

----- Original Message ----- 
From: "Bijan Parsia" <bparsia@cs.man.ac.uk>
To: "Maciej Gawinecki" <mgawinecki@gmail.com>
Cc: <semantic-web@w3.org>
Sent: Tuesday, July 01, 2008 3:53 AM
Subject: Re: comparing XML and RDF data models


> 
> On 1 Jul 2008, at 11:21, Maciej Gawinecki wrote:
> 
>> In one of the article comparing two data models: XML and RDF I  
>> found a statement stating that (I'm loosely citing from my memory):
>>
>>   Searching XML with XPath query expression is easy if you know the
>>   schema of the document being quiried.
> 
> I don't think that knowing the schema is remotely necessary. XPath is  
> not schema aware, for example. I'd hazard that most XPath is over  
> merely well formed XML.
> 
> You do need to know something about the structure, but, for example,  
> it's pretty easy to use ancestor and descendent queries to ignore  
> quite a bit of structure.
> 
>> However, the same query will not
>>   work any a document, which is differently structured, but contains
>>   equivalent information.
> 
> If the structure is *far* enough away, then of course. If you renamed  
> everything and leave the structure intact, this is true too. It's  
> also true for RDF>
> 
>> This can be solved by usage of RDF model,
>>   which can be then queried with RDQL or SPARQL query.
>>
>> Is that really true, that XPath-based XML search is limited due to  
>> its structure?
> 
> In a restricted sense, yes.
> 
>> Yes, that's why there is a great research on keyword-based quering  
>> of XML documents (not knowing schema in advance).
> 
> This won't help if names change (which is a kind of structural change).
> 
>> But is it RDF really better for this issue ?
> [snip]
> 
> Not even a little bit.
> 
> Consider changing from a data valued property to an intermediate  
> object. I.e.,
> 
> s weighs "10".
> 
> to
> s weighs _:x.
> _x: weightvalue "10".
> _x: atTime "...".
> 
> You have to change the query in SPARQL. In XML it's pretty easy to  
> maintain your xpath, e.g.,
> 
> <Weight name="S" value="10"/>
> 
> vs
> 
> <Weight name="S" value=10 timeRecorded="..."/>
> 
> The same xpath will get the name and value.
> 
> Of course if you shift from attributes to elements, you'll have made  
> too big a structural change for that xpath. But so?
> 
> Bijan.
> 
> 
>
Dick McCullough
http://mKRmKE.org/
Ayn Rand do speak od mKR done;
knowledge := man do identify od existent done;
knowledge haspart proposition list;
mKE do enhance od "Real Intelligence" done;

Received on Tuesday, 1 July 2008 23:12:20 UTC