- From: Dave Reynolds <der@hplb.hpl.hp.com>
- Date: Mon, 25 Jun 2007 11:06:40 +0100
- To: Michael Kifer <kifer@cs.sunysb.edu>
- CC: RIF <public-rif-wg@w3.org>
Michael Kifer wrote:
>> There is a second, related, dataset issue I'd like to get clearer on.
>>
>> Will we support dataset-specific queries in the core?
>
> This is actually absolutely essential to make RIF useful for data
> integration on the Web.
I'm glad we are agreed.
>> This could be achieved by having some builtin in the library that can
>> query a dataset, such as the SPARQL blackbox we have talked about before:
>>
>> SPARQL(dataset-id-list, query-string, var1, ... varn)
>>
>> However, I wonder whether it would be possible/reasonable to have the
>> frame terms include an optional datasource identifier:
>>
>> oid{datasource}[p->v, ... p'->v']
>>
>> N.B. I don't care about the human readable syntax, this is just to give
>> a way to discuss it.
>
> A conceptually better syntax is
>
> oid[p->v, ... p'->v']@datasource
> pred(....)@datasource
>
> The important point here is not the exact syntax, but an emphasis on the
> fact that we are asking queries (the part left of @) against a knowledge base
> (a logical theory), which is to the right of @.
Sure.
> Note that this is not (and should not be) specific to RDF. Scoped inference
> is a generally useful facility for distributed (and even non-distributed)
> knowledge bases.
Sure.
>> Thus the facts would be partitioned into a set of fact datasets, one
>> default anonymous one and a set of named ones identified by URIs.
>
> Does not need to be identified by a URI. This facility is also very useful
> for modularization of a KB. It is the same issue as global/local Ids for
> predicates.
Again we have the same mild disagreement as we did over predicates :-)
To me local/global scope is a different issue from uniqueness of names.
I start from the position that this is a web (interchange) language and
everything should be identified by a URI unless there is a good reason
not to. Since every RIF document will have an (implicit or explicit)
base URI then regarding "local" module names as relative URIs seems
reasonable to me. Whereas having modules nameable by both strings and
URIs seems like an unnecessary complication.
That small point aside it's good we agree that something along these
lines would be valuable.
Dave
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Received on Monday, 25 June 2007 10:07:02 UTC