This discussion is very interesting ... and joins well with what I have been thinking and discussing and learning the last few months.
XML , HyperMedia, RDF , Web, InfoSpace
Trying to be concise ... (ha!)
There is this fuzzy space where XML doesnt exactly define how to resolve references to documents, nor does it supply a unique document ID.
( I am not quite sure of the later ... is doc("x" ) == doc("x") ? )
How do we make a Web based InfoSpace that is reliable ... without having to have a local copy of it all ?
I suggest the web works today because of *humans*. It is us humans that clickityclick the links and handle failover ... "Hmm google is down try yahoo",