A few initial questions

[Ling <ma...@gmail.com>]

Hi, very happy to join the Jena community. To start with, I have a few
basic questions:
1) Is Jena still active in development, and with a good user community?
2) Anyone know of any commercial use of it?
3) For millions of entities and relationships, will there an efficiency
problem?
4) Can Jena handle OWL ontology which are created by Protege?

Thank you in advance for comments or advice.

Martin

Re: A few initial questions

[Dave Reynolds <da...@gmail.com>]

Hi,

On 08/01/17 23:25, Ling wrote:
> Hi, very happy to join the Jena community. To start with, I have a few
> basic questions:
> 1) Is Jena still active in development, and with a good user community?

Yes.

> 2) Anyone know of any commercial use of it?

Yes, lots. If you look back through the mail list you'll see various 
threads on this type question with a good range of examples of 
commercial use, there was one such thread late last year if I recall 
correctly.

> 3) For millions of entities and relationships, will there an efficiency
> problem?

We (and others) run multiple production services with hundreds of 
millions of triples. Efficiency is sufficient for our purposes.

Of course the specifics matter!

> 4) Can Jena handle OWL ontology which are created by Protege?

Jena can read and access OWL ontologies. It provides a convenience API 
for accessing OWL 1 ontologies. There is no equivalent for OWL 2 though 
since OWL is encoded on top of RDF it is still possible to access OWL 2 
ontologies through Jena, just takes more work.

Inference support for fragments of OWL 1 is provided out of the box and 
there are third party reasoners such as Protege. However, OWL inference 
at scale over large persistent models is not particularly well supported.

Dave