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Real-world use case for 3.10(a)

From: Chris Wilper <cwilper@cs.cornell.edu>
Date: Tue, 6 Jul 2004 13:25:27 -0400
Message-ID: <772EF7E386FEDF4FA6E11A9DA703A4D2046968@EXCHVS1.cs.cornell.edu>
To: <public-rdf-dawg-comments@w3.org>


Looking at the Requirements/Use Cases document, I noticed that 3.10 and 3.10a
had "Pending" status.  We[1] plan on using an rdf triplestore to back a large
metadata repository, exposed to other systems via the OAI-PMH[2].  While not
being too domain and protocol-specific here, I'll describe our case:

We have a large collection of metadata in a triplestore that we want to
make available to people through a set of queries.  Someone typically asks,
"Give me the metadata that has changed since last week and is in XYZ
collection", or simply, "Give me all the metadata".

It is a requirement for us that the responses can come in chunks: XML is 
sent over the wire, and rather than require all of our clients (and our
to be able to handle arbitrarily large chunks of xml in one stream, our
can be configured to give only, say 1,000 responses, along with a 
"resumption token" that can be used for subsequent requests.

Without the ability to specify LIMITS/OFFSETS with the triplestore query, we
need to stream everything to disk and manage much more state within our

[1] http://www.fedora.info/ and http://www.nsdl.org/
[2] OAI-PMH is a protocol for exposing xml metadata in a repository.
    See http://www.openarchives.org/OAI/openarchivesprotocol.html

Chris Wilper                                                    
Cornell Digital Library Research Group
Received on Tuesday, 6 July 2004 13:26:55 UTC

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