Re: [ubl] Proposed addition to 2.1 documented constraints - no schema location hints

["G. Ken Holman" <gkholman@CraneSoftwrights.com>]

At 2009-10-16 20:01 +0100, Stephen Green wrote:
>I'm not sure these are necessarily issues of UBL per se.
>If UBL starts to include such as normative requirements
>it looks like meddling or 'nannying' the implementers.

Point taken ... but we already started this nannying, particularly 
for interoperability.

>It would be OK if within the mandate (charter?) of UBL's
>scope but I don't think UBL's charter offically should
>include providing any 'best practice' guidelines for XML
>general use for data interchange.

Then what was the reason for including 6.2 Character Encoding?  For 
interoperability, because all XML processors are required to support 
UTF-8 but not required to support other encodings, UBL has stated 
that for data interchange a UBL document shall be in UTF-8.

Though most XML processors support other encodings, an XML processor 
may not support other encodings, but this isn't an issue for UBL 
because UBL states that UTF-8 shall be used.

Interestingly, I see both "MUST" and "SHOULD" for the same issue in 
the actual documentation for 6.2, but that's another issue for 
editing and NDR review:

   http://docs.oasis-open.org/ubl/os-UBL-2.0/UBL-2.0.html#d0e3610

... and given that an absent encoding= implies UTF-8 or UTF-16 an XML 
declaration without encoding= satisfies the requirement.  Or is 
UTF-16 meant to be expressly prohibited?

>Doing so can surely
>be done by the same people that produce UBL, as a kind
>of 'lessons learned' about use of XML for data interchange

As I'm doing in my classroom.

>but not as normative statements of requirements to be
>part of UBL specs since it is broader than UBL's scope.

Then for xsi:* we don't have to say anything.  It was my personal 
opinion this was in scope.

>Is there anything special about UBL that means it needs
>a special implementation of XML?

Precisely the other way around ... UBL requires UTF-8 so that every 
implementation of UBL doesn't have any concerns about character set.

My intention was that by prohibiting the interchange of xsi:* then 
any model expression of the UBL vocabulary will work without needing 
to know about non-XML concepts like xsi:* that come from W3C Schema.

>What is the difference
>between sending and receiving UBL messages and using
>XML in other ways. If it's the sending and receiving itself
>(interchange) then that is for a wider audience than UBL
>interchange and it should not be that just because it is
>UBL being used for that interchange then these perceived
>best practices MUST be implemented, whether one agrees
>with them or not.

Granted ... but I perceived a constraint like 6.2 to be precisely an 
issue brought to the UBL user's attention that directly impacts on 
*interchange* issues in case trading partners are not using the same 
XML processors.

But as I said, I'll drop this and leave it for the classroom only ... 
I just wanted it discussed in case anyone else felt as I do about 
this issue.  We've already broached interoperability of interchanged 
UBL documents, and this came to mind.

Thanks everyone, for the discussion!

. . . . . . . . Ken

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