Tuesday, December 02, 2003

Blank Nodes

In RDF there are nodes. There are nodes that are resources (with or without URIs) and literals. The ones without URIs are blank nodes. These blank nodes can either be given a name (nodeID) or not. Statements are made of a subject (resource), predicate (resources with URIs) and object (anything). Simple enough.

Now I've been looking across three separate Java implementations. I found 8 implementations of classes designed to use blank nodes (resources without URIs):
* Two in Kowari,
* BNode, BNodeImpl and BNodeNode.
* AResource, Node_Blank and RDFNode.

What is maddening is that they each (well 7 of them) have a different way to get their name. What's even more maddening is this is right. Getting their name isn't a part of the RDF model - the most all of these different blank node implementations probably should have in common is equality and being the same type (just share a marker interface like Serializable).
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