Open Grid Forum: Data Format Description Language Working Group

OGF DFDL Working Group Call, November-18-2009

Attendees
Suman Kalia (IBM)
Steve Hanson (IBM)
Mike Beckerle (Oco)
Alan Powell (IBM)
Steve Marting (Progeny)
Stephanie Fetzer (IBM)
Tim Kimber(IBM)

Apologies
Peter Lambros (IBM)


1.051 Scoping Rules
Reviewed of draft 8. Comments made by Suman and Stephanie will be incorporated. Action Closed

2.061 Refactor dfdl:textNumberFormat to remove dfdl:numberBase.
Reviewed updated spec fragment and approved. Action Closed

3.059: External specification of encoding, byte order
This was largely agreed on last week's call but additional discussion about whether additional properties should have predefined variables. Agreed to add dfdl:binaryFloatRepresentation and dfdl:OutputNewLine. Action closed

4.045 Resolving points of uncertainty - Disciminators
Continue discussion of semantics of discriminators and arrays
Stephanie took us through Mike's example implemented in WTX and number of points emerged.
WTX discriminators (component rules) only resolve an immediate parent.
If  one instance on an array is found then the array is said to be found even if minOccurs are not found. An explicit discriminator would be needed to enforce  minOccurs.
There was also a discussion of the forward referencing permitted which is only to children.

SF agreed to get documentation about WTX discrimination.
 
5.045 Resolving points of uncertainty -  parsing rules
Tim and Alan had sent emails about the rules for scanning or skipping of text fields during parsing. Tim pointed out there there was not way to force skipping of text fields and it was agreed that this was an omission. Tim suggested that  lengthKind should be used to specify whether to scan or skip and that dfdl:length shuold be examined when lengthKind=delimited to decide if it is a fixed/known length delimited field. There was not agreement and we ran out of time. To be continued.

Action 65 raised

8.OGF28 Call for papers
Mike and/or Steve will make a request to a WG presentation

Meeting closed, 15:10

Next call 25 November 13:00 UK

Next action: 066

Actions raised at this meeting
No
Action
064
MB/SH Request WG presentation at OGF 28
065
Resolve parsing rules for various lengthKinds

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
...
09/06: No Progress (low priority)
17/06: SH to check ICU code for lax calendar behaviour
24/06: 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
...
14/10: no progress
21/10: Will produce a list of known issues.
28/10: Discussed ICU farctional seconds behaviour. SF to send latest understanding.
04/11: no progress
11/11: no update
18/11: no update
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 progress
...
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
...
04/11: no progress
11/11: Steve has started to look at this. He has requested a 'consumable' definition of the UPA rules from the XSD WG members. Even non-normative Appendix H in the XSD 1.0 spec is hard to consume.
18/11: no update
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
...
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
28/10: Updated proposal reviewed see minutes
04/11: Discussed semantics of disciminators on arrays. MB to produce examples
11/11: Absorbing action 033 into 045.  Maybe decorated discrminator kinds are needed after all. MB and SF to continue with examples.  
18/11: Went through WTX implementation of example. SF to gather more documentation about WTX discriminator rules.
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.
...
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.
28/10: no progress
04/11: no progress
11/11: no update
18/11: no update
056
MB Resolve lengthUnits=bits including fillbytes
12/08: No Progress
...
28/10: no progress
04/11: MB to look at lengthUnits = bits
11/11: no update
18/11: no update
059
9/9: SH 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
28/10: no progress
04/11: no progress
11/11: SH proposal accepted. One open issue - what is the full list of built-in variables?
18/11: added dfdl:binaryFloatRepresentation and dfdl:OutputNewLine. Action Closed
061
AP 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
28/10: no progress
04/11: no progress
11/11: Reviewed AP proposal, some comments to incorporate.
18/11: Approved latest draft subject to minor comments from SF and SKK. Closed
063
Write DFDL primer and test cases.
11/11: no update
064
MB/SH Request WG presentation at OGF 28
065
Resolve parsing rules for various lengthKinds

Closed actions
No
Action
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.
04/11: defineFormat can only contain one active format block, Drop baseFormat, SKK to produce examples for selectors.
04/11: Further discussion see minutes. SKK to produce examples of selectors.
11/11: Closed. No open questions. Incorporate into spec via work item 051.
18/11: Approved draft 8
059
9/9: SH 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
28/10: no progress
04/11: no progress
11/11: SH proposal accepted. One open issue - what is the full list of built-in variables?
18/11: added dfdl:binaryFloatRepresentation and dfdl:OutputNewLine. Action Closed - work item 064
061
AP 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
28/10: no progress
04/11: no progress
11/11: Reviewed AP proposal, some comments to incorporate.
18/11: Approved latest draft subject to minor comments from SF and SKK. Closed - workitem 065

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
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
062
Drop calendarUseZForUTC. describe zU, IU and TU symbols 037
063
DefineFormat can contain only one active format. Drop baseFormat 037
064
Define how encoding,  byteorder and floating point format externally 037
065
Refactor dfdl:textNumberFormat to remove dfdl:numberBase. 037
066
document scope of selectors 037




Alan Powell

MP 211, IBM UK Labs, Hursley,  Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM     email: alan_powell@uk.ibm.com  
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