# Re: URC's

pays@faugeres.inria.fr
06 Apr 94 05:23:32+0200

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    Date: 06 Apr 94 05:23:32+0200

    From: pays@faugeres.inria.fr

    To: sollins@lcs.mit.edu, uri@bunyip.com

    Subject: Re:  URC's

    Message-Id: <765602612.24283.0-faugeres.inria.fr*@MHS>

Latest message from Karen relally is a proof that there exist
completely different (and even contradictory) view of URC
though her message says the opposite.

In fact Karen description of URC is in my view "self inconsistent",
allow me to try to give a few indications why.

1. If as karen says any one may have a URC with a different content
for the same URN I don't know why this is being discussed in this group,
and I would rather call them SRC Specific Resource Context :-)
as this is no longer Universal and more a personal and changing over
time Context that a specific user associates to an URN.

2. To say that an URC is a bag of attribute-value pairs and an help
to locate/access a document and that the URC will contain the
indication/locator/address of a mapping service does not make sense
(from a very pragmatic point of view):
That would imply that the associated URC is obtained magically
from a URN....

What can be done once we have a name (URN) and only the name?

the only thing avaliable is to submit this name to a directory
service (a name server) in order to obtain associated
attributes/information.
Either the requested information is here (the attribute value pairs)
and that give a definition of the URC : it is the directory entry
which name is the URN
Or the information is not in the entry, which implies that the URC
is an identified external entity for which the directory entry
must provide a name or at least an address/locator

What is the meaning of the mapping service concept use by this URI group?

It can only be a form of name server (eg. a directory service)
which when submitted a name (URN) is able to return one or a more
locators URL.
Remember we had to use a name server to get directly or indirectly
the characteristics. If the name/locator of the mapping service
is found in he URC, then we have in betwee 3 to 5 access to a
name server to get a Locator for the initial URN... Does
that make sense? Which will be the initial name server
in order to bootstrap the process?

In fact very pragmatically I am convinced that we need to limit
to something requiring
a single directory service
or
at most a directory service and a location service

By location service I understand something a la Archie which will
know of the existence of specific copies/instances. However
in this second case plenty remain to be defined for the
spec to become "implementable".

Hope these remarks will help to focus this URC debate to realism/pragmatism?

-- PAP

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