Yesterday I sent an example of a sync problem.
Today I managed to resolve parts of it.
I did not mention yesterday that I am using an OntModel, which seems to be
important to reproduce the problem.
By adding TDB.sycn(ontModel) after the tdbDataSet commit I was able to
solve the problem (partly).
jUnit test:
Dataset tdbDataSet = TDBFactory.createDataset(directory);
TDB.sync(tdbDataSet);
tdbDataSet.begin(ReadWrite.WRITE);
this.model = tdbDataSet.getNamedModel(this.getOntologySchemaIRI());
this.ontModel = ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, model
);
//make some modifications in the ontmodel, e..g change a data property of
an individual named "A".
tdbDataSet.commit();
ontModel.commit();
model.commit();
TDB.sync(ontModel);
TDB.sync(model);
tdbDataSet.close();
Web App:
Dataset tdbDataSet = TDBFactory.createDataset(directory);
*TDBFactory.reset(); *
TDB.sync(tdbDataSet);
tdbDataSet.begin(ReadWrite.READ);
this.model = tdbDataSet.getNamedModel(this.getOntologySchemaIRI());
this.ontModel = ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, model
);
//read data from the ontmodel, e.g.
OntModel ont = this.con.getOntologyModel();
List<Statement> list = new LinkedList<Statement>();
Individual linkedIndividual = ont.getIndividual("A");
com.hp.hpl.jena.rdf.model.StmtIterator it = individual.listProperties();
while (it.hasNext()) {
Statement stmt = it.next();
...
}
tdbDataSet.end();
There is still one problem: The data in the Web app is not refreshed until
I restart the application.
Adding
*TDBFactory.reset(); *
after the initialization of the dtbDataSet solves the problem.
However, I think using TDBFactory.reset(); is bad practice and I want to
avoid it.
Any idea how I can do that?
Thanks,
Andreas
On Wed, Nov 6, 2013 at 8:03 PM, Andreas Grünwald <[email protected]> wrote:
> Hello,
> I have a situation with a very strange behavior which I cannot explain by
> myself:
>
> I have 3 different applications, all running in different Java processes,
> but all on the same computer.
>
> Whenever I update an existing record with Jena TDB then these updates are
> only recognized by the same application. The other applications either do
> not recognize the update at all, or only sporadically.
>
> Here is a detailed description:
>
> - Process A is a very simple unit test. I read the Jena record TDB
> dataset (TDBFactory.createDataset(directory), and the current values. Let's
> say the field 'A.b' of record 'A' has the value 'xxx'. I update the value
> to 'yyy' and persist the change with a commit() followed by end(). During
> the same run I re-read the record and as supposed the value of 'A.b' =
> 'yyy'.
> - When I restart Process A the value of 'A.b' is still 'yyy'.
> - However, when I start the second application (let's say B), which is
> a Wicket-Webapp running with Jetty, the value is still 'xxx'.
>
> I tried quite a lot of things: Besides using TDB transactions properly, I
> also take care that after each commit() the transaction is ended with
> end(). Also, read-transactions are opened with .begin(ReadWrite.READ).
> Additionally, I added TDB.sync(tdbDataSet); although I am not sure if
> this is necessary when using transactions properly.
>
> I am quite confused how this behaviour can appear. A little explanation of
> the underlying transaction handling would be very helpful. Maybe any of you
> has an idea what the reason may be?
>
> I also checked the Jena TDB files and can tell you that after updating the
> single record, the following files are updated (I don't know if this is
> helpful):
> * journal.jrnl
> * node2id
> * nodes.dat
> * nodes.dat-jrnl (0 bytes)
> * prefixes.dat-jrnl (0 bytes)
>
> I apprechiate any help.
> Best, Andreas
>
--
Andreas Grünwald
Tel.: +43 650 77 82340
