Open Grid Forum: Data Format Description Language Working Group

OGF DFDL Working Group Call, May-27-2009

Meeting opened, 14:00 UK

Attendees

Steve Hanson (IBM)
Mike Beckerle (Oco)
Suman Kalia (IBM)
Alan Powell (IBM)

Apologies



Agenda:

1. Go through actions.

Updated below:

2. Completing DFDL V1

3. AOB

Next call 04 June 14:00 UK   Scheduled for 2 hours

Meeting closed, 15:10 UK

Actions raised at this meeting
No
Action
050
27/05: xs:any currently limited to initiated text element. Is this sufficient? Should xs:any in its current form be deferred?

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
026
SH: Envelopes and Payloads
08/04: Not discussed explicity, but recursive use of DFDL is tied up with this
22/04: Two aspects. Firstly compositional - do sufficient mechanisms exist to model an envelope with a payload that varies. Secondly markup syntax - this might be defined in the envelope.
The second of these is very much tied up with the variable markup action 028, so will be considered there. SH to verify the composition aspect.
29/04: SH and AP working on proposal. related to Action 028
06/05: No progress
06/05: No progress
20/05: No Progress
27/05:  Still a number of aspects to be decided.
- Compostion - Does the envelope and payload need to be defined in the same schema or should they be dynamically bound at runtime?
- Compostion- How is a variable payload specified. Choice or xs:any; New action raised to discuss xs:any
- extracting dymanic syntax from data. Covered by action 029 valuecalc.
027
SH: Property precedence tables
08/04: Not discussed
22/04: Two things missing from the existing precedence trees. Firstly, does not show alternates (eg, initiator v initiatorkind). Secondly, need a tree per concrete DFDL object (eg, element). SH to update.
29/04: No progress
06/05: SH is updating tables which will be ready for next call
13/05: SH emailed updated version. AP commented.. See minutes for issues and property changes.
20/05: Updated version circulated. Review before next call and be ready for vote.
27/05: Updated version circulated. more comments raised.
028
SH: Variable markup
08/04: Discussed briefly at end of call, IBM to see whether there any use cases that require recursive use of DFDL.
15/04: Use case was distributed and will be discussed on next call.
22/04: The use case in question is EDI where the terminating markup for the payload segments is defined in the ISA envelope segment. The markup is modelled as an element of simple type where the allowable markup values are defined as enums on the type. But we need to handle two cases - firstly where the envelope is present, so the value used by the payload is taken from the envelope. Secondly where only the payload is present. Here we need a way of scanning for all the enum values, and adopting the one we actually find, when parsing. And using a default when unparsing. SH to explore use of a DFDL variable, where the variable has a default, but also has a type that is the same as the markup element - that way we get to use the enums without defining everything twice.
29/04: SH and AP working on proposal.
06/05: No progress
13/05: No progress
20/05: No Progress
27/05: Progress made and will tie to other actions
029
MB: valueCalc (output length calculation)
08/04: Not discussed
22/04: Action allocated to MB, this is to complete the work started at the Hursley WG F2F meeting.
29/04: No progress
06/05: MB will have update for next call
13/05: MB will have update for next call
20/05: Some progress. will be circulated this week
27/05: MB circulated proposal and got comments. Will update and review on next call
032
DG: Investigate compatibility between DFDL infoset and XDM
08/04: No update
22/04: No update
29/04: No update
06/05: DG indicates will have update next week
13/05: see minutes
20/05: No Progress
27/05: No Progress - Dave can you indicate status?
033
AP/TK: Assert/Discriminator semantics. AP to document. TK to check uses of discriminator besides choice.
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)
036
SH: Provide use case for floating component in a sequence
08/04: Raised
15/04: Use case sent and discussed. SH to do further investigation
22/04: IBM feedback from WTX team is that alternate suggested ways of modelling the EDI floating NTE segment have significant usability issues. The DFDL principle is that for a problem that can be expressed as two-layered, then two DFDL models are needed.  The EDI NTE segment does not fall into this though, as its use is on a per sequence basis.  Ongoing.
29/04: Agreed that need to be in V1. SH to make a proposal
06/05: No progress
20/05: SH has almost completed the proposal
27/05: Proposal circulated and approved
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
038
MB: Submit response to OMG RFI for non-XML standardization
22/04: First step is for MB to mail the OGF Data Area chair to say that we want to submit
29/04: MB has been in contact with OMG and will sunbit dfdl.
06/05: MB has prepared response to OMG. Will send DFDL sepc v033
20/05: Response has been sent to OMG based on v034
27/05: Awaiting response from OMG.
042
MB: Complete variable specification.
To include how properties such as encoding can be set externally. Must be a known variable name.
06/05: No progress
20/05: AP to make proposal
27/05: MB proposed differentiating between input and output variables to avoid unnecessary evaluations during parse and unparse. Need to complete rest of variable specification.
043
13/05:  Types in the infoset.  Currently infoset types have defined value space but that implies a parser would have to validate input. Is this correct?
20/05: SH No progress
27/05: No Progress
044
13/05:  Bidi
20/05: AP: will check what IBM products support.
27/05: Bidi is supported so will be needed in dfdl v1
045
20/05 AP: Speculative Parsing
27/05: Psuedo code has been circulated. Review for next call
047
20/05 AP: Scoping for non-format annotations
27/05: Discussed briefly. AP to distribute
048
20/05: AP investigate Restart
27/05: Suggest RESTART is not part of the scope for DFDL.
049
20/05 AP Built-in specification description and schemas
050
27/05: xs:any currently limited to initiated text element. Is this sufficient? Should xs:any in its current form be deferred?

Closed actions:
046
20/05 AP: Document changes to simple type scoping
27/05: Closed moved to work item

Work items:
No
Item target version status
003
Variables - ??, 2008 (Mike)
005
Improvements on property descriptions - ??, 2008 (All - split TBD)
006
Envelopes and Payloads (Steve) - Apr 30, 2008
007
(from draft 32) valueCalc (Mike) - ??, 2008   mostly
complete
008
(from draft 32) Property precedence for writing (Steve) - under review
009
(from draft 32) Variable markup (Steve) - Mar 31, 2008   proposal needs writing up
011
(from draft 32) How speculative parsing works (combining choice and variable-occurence - currently these are separate) ??, 2008 (IBM)  in progress
012
(from draft 32) Reordering the properties discussion: move representation earlier, improve flow of topics ??, 2008 (Alan) not started
027 Calendar schemes 034
032 Floating components
033 Changes from action 020 and 027 - renaming properties etc
035 Remove unorderedInitiated, add initiated content (a041)
036 Update dfdl schema with change properties (Suman)
037 Infoset text codepage
038 Improve length section
039 Change scoping of simple types (A 046)






Alan Powell

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Notes Id: Alan Powell/UK/IBM     email: alan_powell@uk.ibm.com  
Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898






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