Re: comparing XML and RDF data models

hi Tim,

and what about:
Person
+-----------+----------+
| firstname | lastname |
+-----------+----------+
| ...       |          |

? Or just take schemes with less inherent "common sense" than "Person".
Schemas are always fixed to some certain extent, same with RDF-S. You  
can use OWL-DL for classification, but then at least the rules  
defining your classes are fixed.

If we have heterogeneity (we do), we have to map, transform, etc. - I  
don't have a problem with this, but it's usually becoming bad when you  
need performance.
So why is RDF better then XML? (For me) it's: global URIs and the open  
world assumption <- the key for Web-scale information management as  
well as the possibility to represent the whole graph as triples,  
that's great.

Andy

Web of Data Practitioners Days / Oct 22-23 / Vienna
http://www.webofdata.info
----------------------------------------------------------------------
Dipl.-Ing.(FH) Andreas Langegger
Institute for Applied Knowledge Processing
Johannes Kepler University Linz
A-4040 Linz, Altenberger Straße 69
http://www.langegger.at


On Jul 2, 2008, at 12:25 PM, <tim.glover@bt.com> wrote:

>
>
> I think there is a valid observation to be made about XML and RDF or
> relational representations.
>
> Take the simplest atom of information, "There is a Person named John"
>
> In RDF, there is only one representation;
>
> <Person name John>
>
> In RDBMS there is only one representation
>
> Person
> |------|
> | name |
> |======|
> | John |
> |------|
>
> In XML there are several possible representations, eg
>
> <Person name="John"/>
>
> <Person>
> <name>John</name>
> </Person>
>
> <Person>
> <name value="John">
> </Person>
>
>
> With more complicated data, the possible XML representations vary in
> different ways, and increase exponentially w.r.t. the number of  
> atoms of
> information.  To extract the data from the XML we have to know the
> detailed representation chosen. Saying we can UNION different queries
> misses the point - we still have to write 3 queries. Saying we can use
> transformations misses the point - we still have to write
> transformations.
>
> The issue here is that XML fails to abstract the data from the
> representation as effectively as RDF and RDBMS. In this sense, RDF and
> RDBMS are better data representations than XML.
>
> Tim.
>
>
>
>
> -----Original Message-----
> From: semantic-web-request@w3.org [mailto:semantic-web-request@w3.org]
> On Behalf Of Bijan Parsia
> Sent: 02 July 2008 10:29
> To: Olivier Rossel
> Cc: semantic-web@w3.org
> Subject: Re: comparing XML and RDF data models
>
>
> On 2 Jul 2008, at 08:43, Olivier Rossel wrote:
>
>>> Any XML instance can be considered a compact, early-bound
>>> serialization of an infoset RDF graph.
>>
>> +1.
>> XML is very powerful when it comes to presenting data (because it
>> details how data imbricate with each other). But XML is very  
>> unnatural
>
> No, please no. Don't make such claims without backup. What's
> unnatural for you may be very natural to other people. And
> naturalness doesn't matter if *effectiveness* is at issue.
>
>> when it comes to crawling the data in an unexpected and ever-changing
>> manner (because XML tree structure is chosen once for all,
> [snip]
>
> And this is just false. Google for "open content model". Look at XML
> Schema's "lax" and "skip" validation modes. Consider transformations.
> (I.e., many XML people are perfectly comfortable treating the "input
> tree" as just one step, not a fixed one)
>
> RDF structure is similarly fixed in advanced (by and large).
>
> This kind of talk, aside from being wrong, helps marginalize the
> semantic web and related technologies.
>
> In general, if you are inclined to make a general "betterness" claim
> based on some abstract feature, don't. If you are going to anyway,  
> make
> sure you have every detail nailed with concrete, preferably real
> examples ready to hand. Even then, one is better off just presenting  
> the
> goodness without contrast. If it's good enough, people will come.
>
> Cheers,
> Bijan.
>
>
>
> -----Original Message-----
> From: semantic-web-request@w3.org [mailto:semantic-web-request@w3.org]
> On Behalf Of Bijan Parsia
> Sent: 02 July 2008 10:29
> To: Olivier Rossel
> Cc: semantic-web@w3.org
> Subject: Re: comparing XML and RDF data models
>
>
> On 2 Jul 2008, at 08:43, Olivier Rossel wrote:
>
>>> Any XML instance can be considered a compact, early-bound
>>> serialization of an infoset RDF graph.
>>
>> +1.
>> XML is very powerful when it comes to presenting data (because it
>> details how data imbricate with each other). But XML is very  
>> unnatural
>
> No, please no. Don't make such claims without backup. What's
> unnatural for you may be very natural to other people. And
> naturalness doesn't matter if *effectiveness* is at issue.
>
>> when it comes to crawling the data in an unexpected and ever-changing
>> manner (because XML tree structure is chosen once for all,
> [snip]
>
> And this is just false. Google for "open content model". Look at XML
> Schema's "lax" and "skip" validation modes. Consider transformations.
> (I.e., many XML people are perfectly comfortable treating the "input
> tree" as just one step, not a fixed one)
>
> RDF structure is similarly fixed in advanced (by and large).
>
> This kind of talk, aside from being wrong, helps marginalize the
> semantic web and related technologies.
>
> In general, if you are inclined to make a general "betterness" claim
> based on some abstract feature, don't. If you are going to anyway,  
> make
> sure you have every detail nailed with concrete, preferably real
> examples ready to hand. Even then, one is better off just presenting  
> the
> goodness without contrast. If it's good enough, people will come.
>
> Cheers,
> Bijan.
>
>
>









Web of Data Practitioners Days / Oct 22-23 / Vienna
http://www.webofdata.info
----------------------------------------------------------------------
Dipl.-Ing.(FH) Andreas Langegger
Institute for Applied Knowledge Processing
Johannes Kepler University Linz
A-4040 Linz, Altenberger Straße 69
http://www.langegger.at




Web of Data Practitioners Days / Oct 22-23 / Vienna
http://www.webofdata.info
----------------------------------------------------------------------
Dipl.-Ing.(FH) Andreas Langegger
Institute for Applied Knowledge Processing
Johannes Kepler University Linz
A-4040 Linz, Altenberger Straße 69
http://www.langegger.at

Received on Wednesday, 2 July 2008 11:02:28 UTC