Subject: Re: [Simple] Liaison Statement from the Open Mobile Alliance

From: "Brian McColgan" <[email-masked]>
Date: Thu, 15 Oct 2009 15:47:37 -0400

On Fri, 09 Oct 2009 11:00:54 +0300 Jari wrote:

> I looked at the statement, and except the copy-paste bugs of IANA
files 

> from rfc4826, there's a proposal to add a "schemaLocation" attribute
to

> rls- services schema. This attribute value provides a hint from the
author

> to a  processor regarding the location of a schema document. It is an

> optional value which may help the validation task. Typically however,

> validators have some means to combine multiple schemas (e.g.

> <http://validate.openlaboratory.net/> does also some magic with
multiple 

> schemas), and as such it has also security implications (if tools e.g.

> try to fetch some external schemas). So imo, in any sane practical
service, > you'll disable these hints. So they _can_ exist in specs, but
they don't 

> help practical work where you must most likely anyhow tweak with these

> uris. 

> (and fyi, my preference is to use the registered urn's which don't
much

> help practical work either) 

> br, Jari

Hello Jari,  

As you correctly noted, "schemaLocation" is a 'hint'. A 'hint' by its
very definition is a 'helpful suggestion' - Reference
http://dictionary.reference.com/browse/hint.  With that in mind, why
would IETF not wish to be helpful and direct a reader/implementor to the
location of the relevant XSD?  I would assume that is one reason that
IANA provides these XSD files (i.e. so that the public at large may
discover and make use of these as required).

If IETF were to add an appropriate 'proviso' (e.g. in the Schema header)
that readers/implementors are discouraged from referring to an XSD file
(from a public location - e.g. IANA) on an _ongoing basis_ for the
purposes of validation/etc, would that address your concerns?  I would
also think that IETF would not wish to place a permanent dependancy on
any specific 'validation tool' as each tool has different behavior (i.e.
in terms of gathering or combining referent XSD files).  I would think
that would only come into play if the behavior in question fulfilled a
mandatory aspect of the validation process, as set out by the W3C.

IMHO, a schemaLocation could (and hopefully will) be added as a helpful
convenience to those making use of IETF XMLSchema definitions.  Of
course, suitable 'hints' regarding ongoing use/reference should be
included.

br, Brian.

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From: "Brian McColgan" <[email-masked]>
Date: Fri, 16 Oct 2009 15:44:05 -0400

> On Fri, 2009-10-02 at 20:12 +0200, ext Ben Campbell wrote:
> 
> Am I correct in assuming the schemaLocation attribute is also not in  
> the version in the RFC? (I guess that would be a tricky thing to put  
> in an RFC due to document lifetime issues.)
> Thanks!
> 
> Ben.

My apologies if I was not completely clear in my first response to Jari.

I was referring to the XSD files _as they exist_ on the public IANA site
(_not_ as provided in the IETF rfc's).  As Ben has noted, that would
indeed be a tricky issue to deal with, in terms of maintaining the RFC,
etc.

Hope this clarifies, thanks!
Brian.