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Multiple Named Graph

From: Reto Gmür <reto@apache.org>
Date: Thu, 20 Mar 2014 14:56:10 +0100
Message-ID: <CALvhUEU8nw5KrqcwJ0MKHYmssX+_0Eo5U6n6o-dZ=DQT-B_-qA@mail.gmail.com>
To: "public-ldp@w3.org" <public-ldp@w3.org>, public-ldp-wg@w3.org

I've notice that the latest published version suggest using RDF formats
that support multiple named graphs. For the net-worth example it suggests
using "one named graph for the net worth resource and then two others for
asset and liability containers".

I am irritated by this recommendation. First the specification mandates the
possibility to serialize as turtle which does not currently support
multiple named graphs.

But more importantly I don't see the reason of this splitting of the
information into many graphs and it seems to significantly restrict the
possibilities to implement LDP Servers.

The suggested three graph do not seem to represent three different
information sources with thus potentially contradictory statements. So in
this situation there is typically no quotation-use case with provenance
that must be preserved. Grouping into different graphs what can be safely
expressed in one graph seems to deny the expressive power of RDF and
suggesting that the grouping of triples into different graphs has a
significance beyond provenance.

With the previous published version it was possible to have an LDP
compliant server backed by a single graph. This would be my choice of
implementation if the data has a single provenance and the access
restrictions are the same for all the triples. This change in the new
version seems however to mandate implementation to be based on different
graphs for the different resources.

In my opinion this is a significant loss of flexibility. I would like for
simple implementations based on one graph to be possible. It can also be
useful for an implementation to be based on multiple graphs representing
different provenances or confidentiality but containing descriptions of
larger and possibly overlapping sets of resources. With the latter approach
the resource description accessed through LDP would contain more or less
triples depending on my access rights and the sources I've decided to trust.

Received on Thursday, 20 March 2014 13:56:40 UTC

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