[DFDL-WG] Minutes for OGF DFDL Working Group Call, October-21-2009
Alan Powell
alan_powell at uk.ibm.com
Thu Oct 22 10:06:02 CDT 2009
Open Grid Forum: Data Format Description Language Working Group
OGF DFDL Working Group Call, October-21-2009
Attendees
Suman Kalia (IBM)
Steve Hanson (IBM)
Alan Powell (IBM)
Peter Lambros (IBM)
Steve Marting (Progeny)
Stephanie Fetzer(IBM)
Apologies
Mike Beckerle (Oco)
1. Scoping Rules
Continued the discussion on scoping rules. Alan's had distributed a new
scoping document draft(v6) with input from Steve H and Stephanie. Suman
and Steve H had made comments which we went through on the call.
Suman was concerned that the wording implied that the dfdl:format on the
xs:schema didn't need to provide defaults for all the dfdl:properties
which he thought was a departure from previously. Others pointed out that
that had never been the case and that it was not possible to validation
dfdl:format blocks in isolation only at the point of use.
Discussed whether the dfdl:defineFormat annotations should be in the table
of annotation points. Alan pointed out there were other similar
annotations, defineNumberFormat, etc. Decided to remove from the table but
mention them below as they are only brought in scope when referenced.
Discussed the need for more examples and Alan pointed out that in general
we had agreed that the spec would not contain many examples as the should
also be a primer. Agreed to change one example to element->element ref ->
simpleType.
Steve H suggested that following update to the rules
Rules
1. Create an empty working set of "explicit" properties. Create an
empty working set of "default" properties.
2. Move to the innermost schema component in the chain of
references.
3. Assemble its directly relevant "explicit" properties from its local
dfdl:ref (if present) and its local properties (if present), the latter
overriding the former (that is, local wins). Combine these with the
current working set of "explicit" properties. It is a schema definition
error if there is the same property appears twice. Result is a new working
set of "explicit" properties. Obtain directly relevant "default"
properties from in-scope unnamed dfdl:format block (if present). Combine
these with the current working set of "default" properties, the latter
overriding the former (ie, inner wins). Result is a new working set of
"default" properties.
4. Move to the schema component that references the current component,
and repeat step 3. If there is no referencing component, move to step 5.
5. Validate the resultant set of properties. The "explicit"
properties take priority, "defaults" only used when no "explicit" is
present. It is a schema definition error if a required property is in
neither the "explicit" nor the "default" working sets.
Note: we didn't discuss the suggested change of disallowing multiple
annotations at the same point (other than for selectors) or the same
property in short and long form. Please review this change.
2. Resolving points of uncertainty and parsing rules
Reviewed the latest draft (v5) that Alan had distributed. The only change
was the introduction of the 'potentially uncertain' state discussed on
the call last week. Alan was not overly happy with the new concept and
will try some other way of describing the problem.
3. Comments on Draft 036
No comments received. It is now available on gridforge.
4. Go through remaining actions
Actions updated below
5. Plan to finish DFDL v1
Alan pointed out that in order to meet the target of having the document
ready for approval at the next OGF meeting we need to have all the action
items resolve in the next month or so. Alan will produce an outline
schedule for completing the spec.
Also discussed if there is any technical writer support available within
IBM to edit the specification. Steve H will contact Sandy Gao to see who
edits the XML schema specification
Next call 28 October 13:00 UK
Meeting closed, 14:30
Actions raised at this meeting
No
Action
062
SH investigate technical writer support.
Current Actions:
No
Action
012
AP/SH: Update decimalCalendarScheme
10/9: Not allocated yet
17/9: No update
24/9: Add calendar binary formats to actions
22/10: No progress
16/1: proposal distributed and discussed. Will be redistributed
21/1: add locale,
04/02: changed from locale to specific properties
18/2: Need more investigation of ICU strict/lax behaviour.
08/04: Not discussed
22/04: AP to complete asap once the ICU strict/lax behaviour is
understood.
29/04: No progress
06/05: No progress
13/05: Calendar has been added to latest spec version v034 but still a few
details to clarify.
20/05: No Progress
27/05: No Progress
03/06: No Progress (low priority)
09/06: No Progress (low priority)
17/06: SH to check ICU code for lax calendar behaviour
24/06: no progress
01/07: no progress
15/07: no progress
29/07: no progress
05/08: no progress
12/08: no progress
19/08: Inconsistencies are being found in ICU behaviour so Calendars need
reviewing again.
26/08: Specific three character short time zones may not be maintained
during round tripping when there is more than one short form for a time
zone offset. Because dates and datetimes in the infoset only maintain a
time zone offset so on unparsing it isn't possible to say which short form
will be selected for a particular offset when there is more than one
possible. Need to document.
09/09: no progress
16/09: no progress
30/09: no progress
07/10: no progress
14/10: no progress
21/10: Will produce a list of known issues.
033
MB: Need for scope indicator on discriminator
08/04: In progress within IBM
22/04: Waiting for TK to return from leave to complete.
29/04: TK has sent examples shown need for discriminators beyond choice.
Agreed. MB to respond to TK
06/05: Discussed suggestion of adding type indicator to discriminator. MB
to provide examples.
15/03: Semantic documented in v034. MB to provide examples of need for
scope indicator on discriminator
20/05: MB to provide examples of need for scope indicator on discriminator
(but lower priority than action 029)
27/05: No Progress (lower priority)
....
19/08: No Progress (lower priority)
26/08: No Progress (lower priority)
09/09: no progress
16/09: no progress
30/09: no progress
07/10: no progress
14/10: Action re-titled and assigned to Mike B
21/10: no progress
037
All: Approach for XML Schema 1.0 UPA checks.
22/04: Several non-XML models, when expressed in their most obvious DFDL
Schema form, would fail XML Schema 1.0 Unique Particle Attribution checks
that police model ambiguity. And even re-jigging the model sometimes
fails to fix this. Note this is equally applicable to XMl Schema 1.1 and
1.0. While the DFDL parser/unparser can happily resolve the ambiguities,
the issue is one of definition. If an XSD editor that implements UPA
checks is used to create DFDL Schema, then errors will be flagged. DFDL
may have to adopt the position that:
a)DFDL parser/unparser will not implement some/all UPA checks (exact
checks tbd)
b) XML Schema editors that implement UPA checks will not be suitable for
all DFDL models
c) If DFDL annotations are removed, the resulting pure XSD will not always
be valid (ie, the equivalent XML is ambiguous and can't be modelled by XML
Schema 1.0)
Ongoing in case another solution can be found.
29/04: Will ask DG and S Gao for opinion before closing
06/05: Discussed S Gao email and suggestions. Decided need to review all
XML UPA rules and decide which apply to dfdl.
20/05: SH or SKK to investigate
27/05: No Progress
03/06: The concern is that some dfdl schemas will fail UPA check when
validation is turned on or when editted using tooling that enforces UPA
checks. Renaming fields will resolve some/most issues. Need documentation
that describes issue and best practice.
17/06: no change
24/06: no change
01/07: no prgress
15/07: No Progress (lower priority)
29/07: No Progress (lower priority)
05/08: No Progress (lower priority)
12/08: No Progress (lower priority)
19/08: Clarify that this action is to go through the XML UPA checks to
assess impact on dfdl schemas and advice best practice. Name clashes is
just one example. SH or SKK
26/08: No Progress (lower priority)
09/09: no progress
16/09: no progress
30/09: no progress
07/10: no progress
14/10: no progress
21/10: no progress
045
20/05 AP: Speculative Parsing
27/05: Psuedo code has been circulated. Review for next call
03/06: Comments received and will be incorporated
09/06: Progress but not discussed
17/06: Discussed briefly
24/06: No Progress
01/07: No Progress
15/07: No progress. MB not happy with the way the algorithm is documented,
need to find a better way.
29/07: No Progress
05/08: No Progress. Will document behaviour as a set of rules.
12/08: No Progress
19/08: No Progress
26/08: No Progress
09/09: no progress
16/09: no progress
30/09: AP distributed proposal and others commented. Brief discussion AP
to incorporate update and reissue
07/10: Updated proposal was discussed.Comments will be incorporated into
the next version.
14/10: Alan to update proposal to include array scenario where minOccurs >
0
21/10: Updated proposal reviewed
049
20/05 AP Built-in specification description and schemas
03/06: not discussed
24/06: No Progress
24/06: No Progress (hope to get these from test cases)
15/07: No progress. Once available, the examples in the spec should use
the dfdl:defineFormat annotations they provide.
.....
19/08: No Progress (lower priority)
26/08: No Progress (lower priority)
09/09: no progress
30/09: no progress
07/10: no progress
14/10: no progress
21/10: Discussed the real need for this being in the specification. It
seemed that the main value is it define a schema location for downloading
'known' defaults from the web.
051
Scoping rules.
MB: to document change to scoping rules to satisfy implementation concerns
17/06: MB and SH proposals discussed. Needs further discussion
24/06: AP to update presentation with latest proosal
24/06: AP had updated presentation. MB to review
08/07: Discussed at length. Simple types will now take annotations.
Variables will be used for parameters.
15/07: No further progress. Needs final write up.
29/07: No Progress
05/08: No Progress
12/08: No Progress
19/08: AP will document new syntax rules.
26/08: No Progress
09/09: AP has documented new scoping rules. Not discussed
16/09: Not disussed. AP to update element reference examples
30/09: Significant dissatisfaction with proposed new rules. New proposal
developed during call. AP to document.
07/10: New proposal was refined. Details in minutes.
14/10: Discussed at length. Details in minutes.
21/10: Discussed at length. Details in minutes.
056
resolve lenghtUnit=bits including fillbytes
12/08: No Progress
19/08: No Progress
26/08: No Progress
09/09: no progress
30/09: no progress
07/10: no progress
14/10: no progress
21/10: no progress
059
9/9: define how encoding, byteorder and floating point format externally
16/09: no progress
07/10: no progress
14/10: no progress
21/10: SH to investigate
061
Refactor dfdl:textNumberFormat to remove dfdl:numberBase.
14/10: Base 2, 8, 16 numbers are invariably integers without formatting,
use of pattern etc is overkill
21/10: no progress
062
SH investigate technical writer support.
Closed actions:
054
ICU DecimalNumber/ Calendar behaviour
15/07: No progress
29/07: No Progress.
05/08: No Progress. This action is to discover and document ICU behaviour.
DFDL will do whatever ICU does.
12/08: No Progress
19/09: More examples of inconsistent behaviour discovered
09/09: no progress
16/09: no progress
30/09: no progress
07/10: no progress
14/10: no progress
21/10: Decided to list the know issues and combine with action 012 .Closed
Work items:
No
Item
target version
status
005
Improvements on property descriptions
not started
011
How speculative parsing works (combining choice and variable-occurence -
currently these are separate) (from action 045)
awaiting completion of actions 045
012
Reordering the properties discussion: move representation earlier, improve
flow of topics
not started
033
Numeric data - what physical reps are allowed for what logical types (from
action 020)
037
ensure all behaviour documented
036
Update dfdl schema with change properties
ongoing
038
Improve length section including bit handling
some improvement in 036
042
Mapping of the DFDL infoset to XDM
none
not required for V1 specification
051
Revised scoping rules (from action 051)
037
awaiting completion of action 051
058
textPadCharacter %#rxx limitation and split to textxxxxPadCharacter
037
059
limit terminatorCanBeMissing to last element in schema. Ignore elsewhere.
037
060
New empty string semantic for dfdl:binaryBooleanTrueRep
037
061
Change maxOccurs violations from processing error to validation error (if
not 'fixed')
037
ã Copyright IBM Corp. 1998, 2007 All Rights Reserved
Alan Powell
MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM email: alan_powell at uk.ibm.com
Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
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