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FROM and FROM NAMED: To fetch or not to fetch?

From: David Booth <david@dbooth.org>
Date: Sat, 02 Jun 2012 23:42:22 -0400
To: public-rdf-dawg-comments <public-rdf-dawg-comments@w3.org>
Message-ID: <1338694942.18938.6708.camel@dbooth-laptop>
When a SPARQL query is issued to a server using the FROM <U> (or FROM
NAMED <U>) syntax, is the server supposed to fetch that graph from U or
is it supposed to only look among its existing named graphs for U?

Sec 13.2 says:
The FROM and FROM NAMED keywords allow a query to specify an RDF dataset
by reference; they indicate that the dataset should include graphs that
are obtained from representations of the resources identified by the
given IRIs (i.e. the absolute form of the given IRI references).

And sec 13.2.2 further says:
The FROM NAMED syntax suggests that the IRI identifies the corresponding
graph, but the relationship between an IRI and a graph in an RDF dataset
is indirect.

These sections certainly make it sound like the server is supposed to
fetch from the URI (or perhaps use a cached version if it is fresh).
But I just tried this with three different SPARQL servers, and only one
fetches from the URI.  The others only look among their existing named

There is a big difference between fetching and not fetching.  As a query
writer I need to know which behavior is correct.  

Personally, although the fetching behavior seems convenient for some
things, I think the non-fetching behavior seems more sensible, because: 

1. If the correct behavior were to not fetch, then named graphs could be
fetched using LOAD INTO GRAPH anyway.

2. If the correct behavior were to fetch then I don't know how one would
specify multiple already-loaded named graphs to be used as the default
graph in a query.

3. If the spec is intentionally ambiguous about fetching or not fetching
then that would be a problem, because I certainly would not want a
server trying to fetch without my control.

Clarification please?


David Booth, Ph.D.

Opinions expressed herein are those of the author and do not necessarily
reflect those of his employer.
Received on Sunday, 3 June 2012 03:42:55 UTC

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