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Re: Mutability and graphs [was: Re: page about the term "named graphs"]

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Sat, 24 Jul 2010 11:25:12 +0100
Message-ID: <4C4ABF88.7080409@epimorphics.com>
To: Axel Polleres <axel.polleres@deri.org>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>


On 23/07/2010 10:12 PM, Axel Polleres wrote:
> There is a reason, why I "don't like" the graph store being decoupled from the
> (default) dataset of a SPARQL endpoint: It means that they can be completely
> different a SPARQL endpoint can have an update interface, but the updates have no effect
> whatsoever on the queries I can do on that endpoint. That doesn't make sense to me, respectively,
> if I want to support that, then why not having a different endpoint for update and
> query in first place. I think coupling the default data set and the graph store makes sense
> in most cases and is intuitive.

I agree a common usage pattern will be that the updatable graph store 
and the queriable datasets are the same but there are a lot of 
possibilities here and I don't think we should constrain them by 
coupling the dataset and graph store too much.  If we need to relate 
them, isn't it better to do that in service description?  Although an 
app has a somewhat different relationship to updatable data than data it 
only reads. (Do you search the web for data to update?)

Example:
The query dataset might be larger than the update graph store - some 
additional graphs might be derivable from updatable ones (e.g. the base 
data for an inference-providing graph - change the base data and to a 
subsequent query the other graph is different).

	Andy

>> >  So we have 3 ways here:
>> >
>> >  GS-1: A graph store is a container of a datasets and operations change
>> >  the state of the graph store from one dataset to another.
>> >
>> >  GS-2: A graph store is a mutable container with one unnamed and zero or
>> >  more named slots, each slot holds a graph (value).
>> >
>> >  GS-3: A graph store is a mutable container with one unnamed and zero or
>> >  more named slots, each slot holds a mutable container of triples.
>> >
>> >  GS-1 is the way you describe at the end of your message.  More below.
>> >
> yes.

>> >  That style of definition works with declarative RDF dataset as defined
>> >  by SPARQL 1.0 because at no point are you changing (mutating) the
>> >  dataset. You are assigning a new state to the graph store and the state
>> >  is a dataset.
> yes. true, it also should work with the current def of dataset...
> in which my personal main concern about the the fact that dataset
> and graphstore used different definitions is settled. Or at least with that
> GS-1 definition I find the connection intuitive.
Received on Saturday, 24 July 2010 10:25:38 GMT

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