Based on current implementation, the following methods I think should throw a exception, something like:

ResourceNotFoundException

org.drools.compiler.PackageBuilder.addKnowledgeResource()

org.drools.builder.impl.KnowledgeBuilderImpl.add()

another option might be to verify the validity of a Resource object at creation time and make ResourceFactory factory methods throw ResourceNotFoundException.

I believe the case of a "not found resource" the user of the api should be "ecouraged" to handle.

Another case that might be needed to be handled could be InvalidResource?

Let me know what you guys think

Regards

--zoly