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The structure of URNs provides just enough of a toe-hold to
facilitate scalable, distributed resolution. Resolution is a process
by which a client may access the resource
named by a URN. It works as follows:
The client queries a well-known registry for information about the
namespace identifier. The information returned will either indicate
services and locations for all URNs with that identifier, or it will
contain instructions, specific to that name space, which indicate the
location of the naming authority within the NSS, and where to find the
registries for that naming authority.
In the latter case, the naming authority is extracted from the URN and
one of the registries for that naming authority is queried.
Each registry queried returns either (a) referral instructions for
further queries (for a narrower portion of the name space) or (b) a
list of services, locations of those services, and protocols which may
be used when communicating with those services.
When the latter is found, the resolution process stops, and the client
chooses one of the available services and locations. Among the
services provided by RCDS are: URN-to-catalog record mapping and
The resolution process allows for mutiple servers at each registry, so
it is both scalable (allowing the load to be split across multiple
servers) and fault-tolerant (if a query fails at one server, the same
query may be submitted to a different server).
RCDS clients may also be configured to consult ``proxy'' resolution
servers (which perform queries on behalf of clients and cache results)
as well as ``fallback'' resolution servers (which can be consulted
when there are no ``official'' servers for a domain or when the
``official'' servers do not respond.)
Fri Feb 7 11:53:58 EST 1997