W3C home > Mailing lists > Public > public-ldp@w3.org > March 2014

Re: Multiple Named Graph

From: <henry.story@bblfish.net>
Date: Fri, 21 Mar 2014 00:27:34 +0100
Cc: "public-ldp@w3.org" <public-ldp@w3.org>, public-ldp-wg@w3.org
Message-Id: <7CC0C5CF-58FC-443C-812A-0EBF8D1D7D24@bblfish.net>
To: Reto Gmür <reto@apache.org>

On 20 Mar 2014, at 14:56, Reto Gmür <reto@apache.org> wrote:

> Hello,
> 
> 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.

I think you can do that with a DirectContainer. You can put your ldp:contains and all the rest of your triples in the same graph. Some people fought very hard
for what seems on the whole like a pretty bad idea. The circumstances under which that may be a good idea is vanishingly small.

> 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.
> 
> Cheers,
> Reto  
> 

Social Web Architect
http://bblfish.net/


Received on Thursday, 20 March 2014 23:35:17 UTC

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