[DFDL-WG] Minutes for OGF DFDL Working Group Call, June-03-2009

[Alan Powell]

Open Grid Forum: Data Format Description Language Working Group

OGF DFDL Working Group Call, June-03-2009 

Meeting opened, 14:00 UK

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

Apologies



Agenda:
1. Go through actions. 

Action 26: Envelopes and payloads
Extensive discussion of the file path example. 
SH is working on using variables to allow a body structure (global 
element) to be used either stand alone or wrapped by an envelope.

Agreed that DFDL will not support the dynamic binding of payloads to 
envelopes at runtime. Both the envelope and payload must be defined 
(probably using import) in the same dfdl schema.

Action 27 Property precedence

Work on precedence tables highlighted missing design for outputMinLength. 
AP distributed proposal which used lengthkind to control minimum padding 
behaviour. Group decided to modify this so that 
-  outputMinLength was only used on types that did not  have a minLength 
facet
- should  document that outputMinLength=0 is the same as turning padding 
off.
Converted to work item


2.  DFDL V1 Workshop

IBM are to make concerted effort over the next 2 weeks to resolve all the 
actions. Conference calls will be held on the same number at the same time 
Monday 8th -Wednesday 10th and Tuesday - Wednesday 16th

3. dfdl:textBooleanIgnoreCase 

If has been suggested that it would be helpful to ignore the case on 
textBooleanTrueRep and textBooleanFalseRep. Options are a 
textBooleanIngoreCase propety or allow a list of values for 
textBooleanTrue/falseRep 

This will be included in Variable markup discussion

Next call 10 June 14:00 UK   Scheduled for 2 hours

Meeting closed, 16:15 UK

Actions raised at this meeting

No
Action 












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)
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.
03/06: Dynamic runtime binding will not be supported.
SH investigating use of variables to enable standalone and use in envelope 
of global element.
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. 
03/06: Further updates to clarify 'core'. Also identified missing design 
for outputMinLength
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
03/06: General desire to avoid having to introduce variable markup in V1.
Proposed having a property to control case behaviour of all syntax 
(initiator, terminator,separator) rather than separate ones for each. 
Similar property to 'values' (textZeroRep, textBooleanTrueRep, etc). and 
allowing lists of values. SH need to solve remaining uses case as 
described in action 026
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
03/06: Discussed proposal. MB to update dealing with uses cases raised. 
Options include a new lenghtKind='Reference' to make it easier to 
distinguish from fixed length case. Or use outputLengthCalc to separate 
calculation of parsing and unparsing length.


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)
03/06: No Progress (lower priority)
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.
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. 
03/06: On hold
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.
03/06: Pointed out problem of declaring variables input or output when 
used to define syntax which is used both times. MB to update proposal to 
include how variables are set externally and how specific properties  such 
as encoding are set.
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
03/06: 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
03/06: 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
047
20/05 AP: Scoping for non-format annotations
27/05: Discussed briefly. AP to distribute
03/06: Proposal discussed briefly. Will be updated.
048
20/05: AP investigate Restart
27/05: Suggest RESTART is not part of the scope for DFDL.
03/06: not discussed
049
20/05 AP Built-in specification description and schemas
03/06: not discussed
050
27/05: xs:any currently limited to initiated text element. Is this 
sufficient? Should xs:any in its current form be deferred?
03/06: not discussed



Closed actions:

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
03/06: Closed
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?
03/06: A mapping of the dfdl infoset to XDM needs to be provided. 
Converted 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)


040
Document outputMinLength  (A027)


041
Floating  (a036)


042
mapping of the dfdl infoset to XDM 

Not required for V1 specification






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






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