Wednesday, January 23, 2008

Nodes by Type

JRDF 0.5.3 released. This has a couple of bug fixes and features added. The find with no constraints (find(ANY_SUBJECT_NODE, ANY_PREDICATE_NODE, ANY_OBJECT_NODE)) has always been fast with the on disk version but not if it was constrained in anyway (a fixed subject for instance). This was because the wrong method on the btree was being called. This is a big improvement in performance obviously.

A cleanup on the Graph interface also occurred. There were all these methods like findUniquePredicates, getBlankNodes and getResources. There is now findNodes(NodeType) where NodeType is any of the positional (SPO) or value (Resource, URIRef, bnode, Literal) node types. This was able to be done because JRDF has a NodeTypePool where all nodes are in maps by their type. It is missing some types being supported but that should be done next release.

The other thing that was very annoying and now fixed was that a Literal or URI Reference had to be added via the GraphElementFactory before you could add it to the Graph. This only makes sense for blank nodes - other node types can just be re-localized (get their internal node id) each time. Handy for the amount of graph copying we have done lately.

There were some other boring changes like a bug fix to the RDF/XML parser and TripleImpl now being null proof.

Much more to do - haven't had a chance to cleanup the Molecule implementation or add the persistence support.
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