Re: [NGO] Diff-Serv datamodel for discussion startpoint

[Ladislav Lhotka <lhotka at cesnet.cz>]

Hi Martin,

the key problem (and similar ones) can be solved in RELAX NG by adding
certain "hints" in a separate namespace to the schema. Actually, we use
this approach in the FlowMon schema I mentioned in my previous mail
(http://www.flowmon.org/flowmon-probe/devel/config/flowmon-rng/), look
for the h:key attribute.

You are right about the limitations of the ID/IDREF datatypes, I also
prefer application-specific and more focused links and anchors. Again,
one could use a pair of hints to instruct applications to check
uniqueness of the keys within a certain scope, existence of link targets
etc.

Lada

PS. Note that I don't want to advocate anything in the diffserv schema,
my only ambition was - as I promised during the netconf session on
Monday - to write a RELAX NG equivalent of the original XSD schema.
 
Martin Bjorklund píše v St 21. 03. 2007 v 11:29 +0100:
> Hi,
> 
> I will point out just one problem with both the XSD and the RelaxNG
> versions of this datamodel.  None of them contain any key (or INDEX if
> you will) information.  So how is this supposed to work with a NETCONF
> <edit-config> operation?  (The problem has been discussed several
> times on the list, e.g. in threads
> http://ops.ietf.org/lists/netconf/netconf.2006/msg00215.html and 
> http://ops.ietf.org/lists/netconf/netconf.2006/msg00054.html)
> 
> For XSD, it could have been solved by using a xs:key expression, but
> wasn't.  RelaxNG does not have the key concept.
> 
> Ok, I'll point out one more problem - the intention *might* have been
> that the 'name' attribute is the key.  But the 'name' attribute is of
> type xs:ID.  This isn't very scalable since the ID must be unique
> within an instance document, which means that if you do a <get/> you
> will get the entire datastore, and if you use another ID somewhere
> else in the datastore, you might get a collision.
> 
> 
> /martin
-- 
Ladislav Lhotka, CESNET
PGP Key ID: E74E8C0C


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