Practical RDF

Chapter 8. Jena: RDF in Java

Hewlett-Packard’s Semantic Web team has been quietly working on Jena—a full-featured Java API for RDF—about as long as work has been progressing on RDF itself. In fact, the cochair of the RDF Working Group is Brian McBride, one of the creators of Jena.

Jena is an open source API and toolkit, accessible at Source Forge (http://sourceforge.net/projects/jena) or at http://www.hpl.hp.com/semweb/jena.htm. In addition, there’s a Jena developers’ discussion forum at http://groups.yahoo.com/group/jena-dev/.

Overview of the Classes

Included with the Jena toolkit are the dependencies and installation instructions, which I won’t repeat here. I have worked with Jena on Linux (Red Hat), FreeBSD, and Windows; the examples included with Jena and the examples in this chapter work equally well in all environments. The only requirement is that you use JRE 1.2 or above.

A description of the many Java classes included with Jena is included with the installation (as Javadocs). I won’t cover all of them here, only those most critical to understanding the underlying architecture in Jena.

Tip

I used Jena 1.6.1 in this chapter, but by the time this book is out, Jena 2.0 should be available. The Jena developers are refactoring many of the classes, changing class structure as well as making modifications to the API itself. These changes will break these examples, unfortunately. However, the concepts behind the examples should stay the same, and the book support site will have updated ...