DHT point is rendezvous point
Use tools to guid user register/query. can specify the hierarchical topic.
register: read ontology from a peer, recursively trace the ontology up to the mnost general form: thing.
inside the cluster use different grained index: RDF, concept keyword, general ontology namespace?
use ontology assist search: e.g. user search for unix os, resource has SunOS, or AIX, according to ontology, we know SunOs isSubClassOf unix.
or, search lecture, resource has instructor, ontology: lecture isEqivalentTo instructor.
Can add some human based interference, automatic is not the best.
add path info when forwarding query, so avoid cycle.
