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Re: API for querying a set of RDF graphs?

From: Reto Bachmann-Gmuer <reto@gmuer.ch>
Date: Wed, 19 Mar 2003 12:03:01 +0100
To: www-rdf-interest@w3.org
Message-Id: <5A0D5680-59FA-11D7-BE8D-003065CDBE5C@gmuer.ch>

Hash: SHA1

I'm wondering if it's a good idea to have multiple graphs. Wouldn't it 
be more flexible to reify the statements depending on their source  in 
the style "a says (s p v)" ? In this case the source is determined by a 
resource within your graph instead of a separate graph. You can then 
add property to the source, such as "a hasThrust 0.7" and use inference 
to query all statements said by someone with trust higher than 0.5.


PS: Does your project have an URL? I'd like to find out more. Too see 
the p2p/semantic web project I'm involved check out 

Mercoledý, 19 Mar 2003, alle 08:57 Europe/Paris, Benja Fallenstein ha 

> Dear James,
> LYNN,JAMES (HP-USA,ex1) wrote:
>> You may want to take a look at Jena (and the new version Jena 2).
>> http://www.hpl.hp.com/semweb/index.htm
>> You can get a quick look at the current query capabilities from the
>> tutorial. Look at the section on RDQL.
>> http://www.hpl.hp.com/semweb/doc/tutorial/index.html
> I know about Jena and counted it among the query-a-single-graph APIs. 
> In fact, the examples given in the tutorial seem to support this 
> interpretation-- they seem to be queries on a single graph, and they 
> do not seem to report which graph results came from.
> If I am understanding the docs wrong here, can you explain where I can 
> find details?
> Thank you,
> - Benja
>> -----Original Message-----
>> From: Benja Fallenstein [mailto:b.fallenstein@gmx.de]
>> Sent: Tuesday, March 18, 2003 5:36 PM
>> To: rdf-i
>> Subject: API for querying a set of RDF graphs?
>> Hi all,
>> I am developing a system that stores a number of RDF graphs, possibly 
>> downloaded from different places, and I need to run queries over that 
>> data. (The store may also be the virtual collection of all graphs 
>> available on a p2p network.) I may not trust all graphs in my store 
>> for all purposes. I'm imagining an API that would let me run simple 
>> queries over all the graphs (individually; I don't need to solve the 
>> harder problem where two graphs taken together answer the query), and 
>> return results together with a tag saying which graph a result came 
>> from. Then I could decide which of the graphs is applicable, meaning 
>> a) trustworthy and b) a current, not an obsoleted version.
>> I've been doing some work on this, but it occurs to me that such an 
>> API would be useful for the Semantic Web in general-- querying a 
>> search engine or similar service for published graphs that answer 
>> some query. So I was wondering, do APIs for this purpose exist-- 
>> especially in Java? The APIs I've looked at so far seem to be geared 
>> at querying a single graph (which may be the virtual union of other 
>> graphs, but such an API would not provide me with information about 
>> which graph a result came from, making it impossible to evaluate 
>> which results can be trusted and which can't).
>> So, which APIs like this are out there?
>> Thanks for your help,
>> - Benja Fallenstein
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Received on Wednesday, 19 March 2003 06:03:11 UTC

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