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From "Nouwt, B. (Barry)" <barry.no...@tno.nl.INVALID>
Subject [UnionModel] question about unexpected behaviour
Date Thu, 26 Sep 2019 09:05:26 GMT
Hi all,

I am trying to get the Apache Jena UnionModel working for my scenario, but I keep encountering
unexpected behavior. I’ve set up a minimal, free-standing example on github in this repository
(clone the git repo, configure Maven in your IDE and execute the main() method, I.e. it probably
does not run from the .jar):

 https://github.com/barrynl/jena-example



I have two questions related to this example:

My first question is related to empty graphs in Jena Fuseki. If I load the conf.ttl (from
the git repo above) at startup in Apache Jena Fuseki without the dummy data in the two named
graphs, the two graphs seem to disappear (I think this does not happen in my Java Example).
I read somewhere that empty graphs are automatically deleted in Fuseki to prevent old graphs
from showing up in the Fuseki interface. For my use case I would like to configure two (possibly
empty at first) named graphs via a conf.ttl and be able to store data in them afterwards.
Is this possible?

My second question is about the demonstraded behaviour of the Java example in the git repository
above. I load a dataset with a UnionModel from a conf.ttl file and insert new data in it via
SPARQL. Although the new data shows up in the select query, it does not show up in either
of the two names graphs the UnionModel consists of. My question is: where is this data stored
if not in one of the names graphs? (If I inspect the UnionModel via a debugger, the inserted
data DOES show up in the correct named graph)

Hopefully someone can shed some light on this behaviour. Thanks in advance!

Regards, Barry
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