All,
I know that you expect me to chime in on substitution groups so here
goes:
If we have determined that minor versions will only have deltas, how does
one obtain a schema to validate against. Substitution groups allows you do that.
Redefine can do some of this too (but we haven't yet gotten this to work with
highly nested schemas).
Thus, it seems we are leaving the user to hand patch his schemas and then
assert that they are valid to UBL 2.1, for example. Or, are we going to provide
a properly edited version 2.1 to place in repositories? If the latter, then we
may as well publish it, rather then the deltas. People can do a "diff" if they
want to see only the deltas.
I may be missing something, but this is some quick input into the
discussion. BTW, I applaud the decision to make minor versions have the same
namespace as the major version and the backwards compatibility statement makes
sense.
Cheers,
Marty
In a message dated 11/3/2005 7:44:34 P.M. Eastern Standard Time,
writes:
MINUTES
OF ATLANTIC UBL TC MEETING
16H00 - 18H00 UTC WEDNESDAY 2 NOVEMBER
2005
ADMINISTRIVIA
It was decided at the close of
this meeting that due to
attendance at XML 2005, we will not
be holding the Atlantic
call 16 November. We *will* be
holding this call at its
regularly scheduled time next week (9
November).
ATTENDANCE
Jon Bosak
(chair)
Mikkel Brun
Mavis
Cournane
Michael Grimley
Betty
Harvey
Bryan Rasmussen
Kumar
Sivaraman
Paul Thorpe
STANDING
ITEMS
Additions to the calendar:
http://ibiblio.org/bosak/ubl/calendar.htm
None.
Review of Pacific and Europe/Asia
calls
No comments.
Schedule
review
Including attendance at April meeting in
Brussels
JB: This meeting is to be hosted by
CEN/ISSS in Brussels the
week of 24 April. It
accidentally got dropped from the 2.0
schedule.
We very much want to accept the offer to host,
but
neither JB nor TM will be available to chair. We need
to know who can commit to be there.
ACTION:
JB to poll the TC for attendance at the April F2F in
Brussels.
ACTION ITEM REVIEW
ACTION: JB to create
the first draft of index.htm.
Status:
Done.
ACTION: TC members visiting NYC in October or
November to check
out the Sun facilities and see whether they
are suitable for a
UBL TC meeting. JB will be coming
through in mid-November and
will also check
then.
Status: Pending.
ACTION:
JB to post a question on ubl-dev: What do other widely
used
schemas do about minor version namespace URIs?
Status: Done.
ACTION: Everyone involved in the development
of the support
pieces to give JB time estimates.
JB: We have estimates for SBS from SG. We still
need
estimates for code lists, HISC, and the business
process
scenarios.
ACTION:
MB to check with PB regarding time estimates for the
business process scenarios.
FOR THIS MEETING
NDR work session:
Minor versioning. See
http://lists.oasis-open.org/archives/ubl/200510/msg00084.html
*** NOTE that as usual, voting members have a week to register
any disagreement with the decisions described below. If
no
disagreement is registered, the decisions arrived at during
the
call will become officially adopted by the TC.
***
Question 1: Should minor-version schemas only contain the
deltas,
or should everything be redeclared (with the
'ccts:Version'
documentation component reflecting the version of
individual
types).
Discussion: Deltas make clear
exactly what's been changed or
added and make it easy to
determine backward compatibility.
AGREED that
minor-version schemas should only contain the
deltas.
Question 1.a: Should we have minor-version spreadsheets that
only
capture the deltas and their relationship to the major
version?
Discussion: Providing full spreadsheets for the
minor version
allows someone coming in at that stage to see
the whole
picture. It also sidesteps the problem of how
to capture the
relationship between major and minor at the
spreadsheet level
(we can just add a flag to mark the items
that have been added
in the minor
version).
AGREED that the minor version spreadsheets
should contain the
entire vocabulary, with a flag to indicate
what has been
changed or added in the minor
version.
AGREED that we thank Bill Burcham for his
contribution of a
method that could have been employed if we
had decided that the
minor version spreadsheets would contain
only the deltas.
Discussion: It may be difficult for tools
to generate the
deltas (see decision on Question 1 above) from
the full
spreadsheets. It's possible that the tool we
use will only be
able to create major version schemas, and
that we will have to
create the minor version schemas by
hand.
AGREED that while we hope that tools can be
configured to
create the minor version delta schemas from the
full
spreadsheets, we are willing to adopt this policy even if
it
means that the minor version schemas have to be created
by
hand.
Question 2: Should the namespace name change
for minor versions?
How about the namespace prefix?
Discussion: Our assumption is that a minor version of UBL may
add new content but will not change the meaning of anything
declared in the major version schemas. It therefore
appears
that the best approach is to separate semantic
identity from
versioning. But doing so will require us
to specify expected
behavior of UBL processors when presented
with instances
exhibiting different versioning
information.
AGREED that minor versions should use the
same namespace as the
major version from which they are
derived (which means, for
example, that the namespace for UBL
2.0 should reference "UBL
2" rather than "2.0") and that the
version should be specified
in a separate attribute
TBD.
AGREED that the namespace prefix stays the same in
minor
versions.
ACTION: NDR editors to
propose a suitable version attribute to
be used by all UBL
instances in time for discussion during the
Atlantic TC call 9
November.
ACTION: At the Manhattan F2F in January, NDR
editors to develop
a specification of expected behavior of UBL
processors when
encountering a version different from the one
for which they
were designed. (For example, UBL
processors expecting a
version 2.x when presented with an
instance conforming to a
later version 2.y might be required
to attempt validation
against the 2.x schemas and reject the
instance if errors are
found.)
Discussion:
We note that some users may not understand that the
specification of namespace prefixes in our NDRs does not
hardwire those prefixes in conformant instances.
ACTION:
At the Manhattan F2F in January, NDR editors to develop
a best
practice note for namespace prefixes. (For example,
"For
ease of comprehension it is recommended that the prefixes
specified in our NDRs are used in instances, but applications
must be able to process arbitrary prefix declarations per the
XML Recommendation.")
Question 3: What, specifically, determines
whether a new version
of the schema is actually a 'minor' or 'major'
release? (If the
schema only includes the deltas, and utilizes
xsd:derivation
concepts, the answer should be simpler than if the
versioning is
strictly model-based.)
Discussion: We
have already adopted the definitions given by
Eduardo Gutentag
in his message of 18 October 2005, but we note
that his
definition of backward compatibility transposes X and
Y:
c) backwards compatibility -- a schema X is
said to be
backwards compatible with a schema Y if
documents that
validate against schema X also validate
against schema Y,
and schema X follows (in time, or in
version) schema Y.
In other words, if all
documents that validate against
MySchema v1.0 also
validate against MySchema v1.1, then
MySchema v1.1 is
said to be backwards compatible; but there
is no
expectation that any document that validates against
MySchema v1.1 must also by necessity validate against
MySchema v1.0
The example shows that the definition should
read "and schema Y
follows (in time, or in version) schema
X."
Question 4: Is (are?) Substitution Groups still on the
table?
AGREED: We will not use substitution groups for
minor
versioning.
Question 5: What should be the
normative version of UBL? Schema,
Model or both.
Discussion: XML inherits from SGML the doctrine that documents
are normatively specified by the combination of formal
declarations plus comments. Properly annotated schema
formalisms such as DTD (W3C), XSD (W3C), RELAX NG (ISO),
Schematron (ISO), and ASN.1 (ITU) are the standard mechanisms
for establishing the validity of XML instances; no such
standard exists for mechanically checking an instance against
a
model. And since there is no way of proving that a
model and a
schema describe exactly the same thing, we cannot
say that both
are normative.
AGREED that
UBL is normatively specified by the schemas plus
associated
normative prose.
Jon Bosak
Chair, OASIS UBL
TC
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