RE: API for querying a set of RDF graphs?

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

James

-----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