I have read some articles commenting about the Apache Jena engine and I have found it really interesting. At their site I have found that in order to store the triples, TDB could be used.
In my case, I would like to know if, from a Jena application would be possible to load data from external databases such as MySql or PostgreSql ones, or it is a "closed" product and you can only interact with TDB and Fuseki frameworks.
At the moment, I don't know if the Jena engine framework could act as a traditional Java war but with the particularities of processing RDF files.
Any help would be apreciated.