On 27/08/2021 12:23, Zak Mc Kracken wrote:
Hi all,
I have a little RDF file (describing a dataset metadata), which I want
to read in an helper class and return as a read-only view on the file.
The reason to return it as read-only is that I also keep a simple cache
of uri/Object, which is a simplified view of RDF resources in the file,
so a modifiable Model would make it impossible to keep the two aligned.
That said, I wonder if there is some read-only wrapper for the Jena's
Model interface, something similar to Collections.unmodifiableXXX(),
which of course, would be based on the decorator pattern, with
delegation to a base Model for most of the interface methods, except
interceptors for addXXX(), which would throw
UnsupportedOperationException. Would be easy to implement it, but I
don't like to reinvent wheels, if something like that already exists.
Apparently there isn't one. Not sure why not.
There is a read-only graph (and a read-only DatasetGraph) so one way to
create a read-only model is:
Model model = ModelFactory.createDefaultModel();
Graph graphRO = new GraphReadOnly(model.getGraph());
Model modelRO = ModelFactory.createModelForGraph(graphRO);
Graph is a narrower interface do catching things here is less code. In
fact, GraphBase is read-only unless add/delete(Triple) are overwritten.
Andy
Thanks,
Marco.
