Open Grid Forum: Data Format Description Language Working Group

OGF DFDL Working Group Call, Nov-04-2009

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

Apologies
Peter Lambros (IBM)

1. 051 Scoping Rules
Continued discussion on draft v7.
After last weeks decision to disallow multiple dfdl:format at the same annotation point, Steve pointed out that dfdl:defineFormat was now inconsistent in that it allowed multiple dfdl:formats.

Decided that dfdl:defineFormat will only allow one dfdl:format annoation.

We then discussed whether it was still necessary to have the dfdl:defineFornat baseFormat property and ref property its only dfdl:format annotation. Having 2 properties allows multiple inheritance but that is inconsistent other places where dfdl:format is used. We noted that the dfdl:format ref property allowed re-factoring more easily than the baseFormat property.

Decided that the baseFormat property is no longer needed and will be removed.

There was a long discussion on the semantics of selectors on the dfdl:format annoations in a dfdl:defineFormat block. Agreed that the current definition that selectors apply independently at each annotation point but added that dfdl:defineFormat is an annotation point equivalent to annotation points on schema components.

Suman agreed to produce some examples to show the semantics of selectors.

2. Resolving points of uncertainty and parsing rules

Discussed the semantics of discriminators on variable length arrays. Went through many examples of behaviours with no firm conclusion that a complete description found. Concluded that the best way forward was to produce a complete set of use cases. Mike B agreed to do this as part of action 033.

4. Go through remaining actions
Actions updated below

5. Plan to finish DFDL v1
We agreed that the target should be to have the DFDL V1 specification ready for public review by OGF 28 in March 2010. Alan will redo the schedule and try to get more details of the OGF process.

Mike suggested that to make the spec useful we also needed a primer and a good set of worked examples that could be used as implementation 'test cases' - Action item raised.
It was noted that the examples in the spec should mainly be to clarify points of semantics and not to explain simple use cases.

We also discussed then need to reorganize the spec to make it more readable, It was felt that it was more important to complete the spec that reorganize it. Alan and Steve H will look at the structure to see how much needs to be done.

Next call 11 November 13:00 UK

Meeting closed, 15:10

Next action: 064

Actions raised at this meeting

No
Action

063
Write DFDL primer and test cases.

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.
28/10: Discussed ICU farctional seconds behaviour. SF to send latest understanding.
04/11: no progress

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
28/10: no progress
04/11: Mike to produce examples for choices with variable occurrence arrays.

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
28/10: no progress
04/11: 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
28/10: Updated proposal reviewed see minutes
04/11: Discussed semantics of disciminators on arrays. MB to produce examples

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.
28/10: no progress
04/11: no progress

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.

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
28/10: no progress
04/11: MB to look at lengthUints = bits

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
28/10: no progress
04/11: no progress

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
28/10: no progress
04/11: no progress

062
SH investigate technical writer support.
28/10: SH had contacted S Gao to understand the W3 process and support.
04/11: no progress

063
Write DFDL primer and test cases.

Closed actions:

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

062
Drop calendarUseZForUTC. describe zU, IU and TU symbols 037

063
DefineFormat can contain only one active format. Drop baseFormat 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
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

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. 28/10: Discussed ICU farctional seconds behaviour. SF to send latest understanding. 04/11: no progress
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 28/10: no progress 04/11: Mike to produce examples for choices with variable occurrence arrays.
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 28/10: no progress 04/11: 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 28/10: Updated proposal reviewed see minutes 04/11: Discussed semantics of disciminators on arrays. MB to produce examples
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. 28/10: no progress 04/11: no progress
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.
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 28/10: no progress 04/11: MB to look at lengthUints = bits
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 28/10: no progress 04/11: no progress
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 28/10: no progress 04/11: no progress
062	SH investigate technical writer support. 28/10: SH had contacted S Gao to understand the W3 process and support. 04/11: no progress
063	Write DFDL primer and test cases.

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
062	Drop calendarUseZForUTC. describe zU, IU and TU symbols	037
063	DefineFormat can contain only one active format. Drop baseFormat	037