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

Received on Tuesday, 18 March 2003 17:38:28 UTC