Does getBaseModel() [1] not work or is this not what need?
Lorenz [1] https://jena.apache.org/documentation/javadoc/jena/org/apache/jena/ontology/OntModel.html#getBaseModel-- On 25.01.2018 06:28, Andrew Hunter wrote: > Hi, > > I have an OntModel using simple RDF reasoning, but I have found that > preparing the model and then copying it into a default, non-reasoning model > is much faster for querying. My immediate question: Is there an efficient > way of copying an OntModel into a default, non-reasoning model without > copying all statements? > > Some more details on my motivation, with a sketch of the code found below: > My OntModel is held in memory and is originally constructed from a set of > OWL files. I am matching a stream of data items, each with a small set of > RDF triples attached, against a few long standing queries. Conceptually, I > wish to insert a data item into the OntModel and then execute the queries > to see if that one item matches, then remove it from the model and wait for > the next item. Since there is only one item of interest at a time, I also > have the option of extracting a sub-model rooted at a resource identifying > the item, and using this much smaller model to query. > > What I have found is that by far the fastest way to complete query > execution is to perform all the reasoning on the ontology and data in the > OntModel, and then to make a copy of all its statements into a default > model, and query over the default model. Since I have several queries, I > actually extract a relevant sub-model using reachableClosure from > ResourceUtils and use this "sub" model. Both the querying and the closure > extraction are dramatically faster with the default model copy over the > OntModel (as I'm sure you all know). > > However, making the copy itself now takes 95+% of the total item matching > time. Hence my question: is there a faster way to make a copy, or reference > the statements in an OntModel as if they were part of a default model? > Alternatively, is there a way of "turning off" the inference functions when > querying (I see no API for this)? My limited understanding of the InfModel > and InfGraph indicates the statements are actually held in multiple graphs > (e.g., the base graph and the deductions graph) so it probably can't be as > easy as "get a reference to the list of statements/triples". > > I also tried implementing ModelChangedListener and GraphListener to extract > the statements being added by the reasoner and add those to the default > model, but these seem to only callback when new data is added from outside. > The idea was that I could add the large set of ontology-based inference > once for all at startup and just make small deltas based on new inferences > from the incoming data, but these small deltas were not reported to me. > > I would be most grateful for any ideas or pointers. In any case, best of > luck and thanks! > > Andy > > > A sketch of my current code: > > // Block executed once at startup > OntModel fullModel = ModelFactory.createOntologyModel( > OntModelSpec.OWL_LITE_MEM_RDFS_INF); > // load ontology files into fullModel with something like > for (each owl file) { fullModel.add( ... ); } > // perform inference over onotlogy > fullModel.prepare(); > // end startup block > > ... > > // new data arrives > fullModel.add( [[model from data string]] ); > // perform inference on new data + ontology > fullModel.prepare(); > // make a copy into a default model > Model copyModel = ModelFactory.createDefaultModel(); > copyModel.add(fullModel); > // extract relevant sub-model > Model subModel = ResourceUtils.reachableClosure(copyModel > .getResource("some:root:data:id:uri")); > > // query uses relevant default model > QueryExection qe = QueryExecutionFactory.create(queryString, subModel); > > // execSelect, process results, cleanup, wait for new data, etc. >
