[DFDL-WG] Minutes for OGF DFDL Working Group Call, Aug-19-2009

Alan Powell alan_powell at uk.ibm.com
Thu Aug 20 10:32:00 CDT 2009


Open Grid Forum: Data Format Description Language Working Group

OGF DFDL Working Group Call, Aug-19-2009

Attendees
Steve Hanson (IBM)
Alan Powell (IBM)
Suman Kalia (IBM)

Apologies
Peter Lambros (IBM)
Mike Beckerle (Oco)

1. Actions discussed and updated below.

2. New occursCountKind for when number of occurrences can be resolved by 
parsing. 
There have been email exchanges on the name of the enumeration and the 
semantics.

Need to decide semantics 
- Find as many repeating elements as possible then validate against 
minOccurs and maxOccurs
- Find up to maxOccurs repeating elements. If less than nimOccurs found 
then processing error.

The spec currently implies the later semantic

3. Make dfdl:initiatedContent discriminating 
SH not happy with last calls decision to make discriminating


Next call 26 August 14:00 UK

Meeting closed, 15:00

Actions raised at this meeting

No
Action 
057
Decide semantics and enumeration for 'parsed'  occursCountKind 
058
Should dfdl:initiatedContent be discriminating?




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.
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)
09/06: No Progress (lower priority)
24/06: No Progress (lower priority)
01/07: No Progress (lower priority)
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: 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.
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
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.
09/06: SKK to use example to dicument his proposal
17/06: SKK to refine proposal. Other aspects need progress.
24/06: SKK proposal discussed but not accepted. PL to document simpler 
proposal.
07/01: PL working on proposal
15/07: PL has distributed his proposal. SH, MB and SKK have commented. 
Broad agreement in principle. Need to agree on better name for 
dfdl:variable to reflect the annotation's purpose. PL to update proposal.
15/07: No Progress 
29/07: No Progress 
05/08: SH and others had commented on Variables [Draft proposal - 
20090715].doc. SH stated that fixOnMatch is not needed in dfdl v1.0
MB will document how to implement fixOnMatch behaviour with existing 
function.  PL to update proposal
12/08: PL to update proposal with SKK examples.
17/08: Chase PL for update
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
09/06: No Progress
24/06: No Progress
01/07: AP started investigation and documented issues. Suggest do whatever 
XML does.
15/07: No further progress
29/07: No Progress 
05/08: AP has been in touch with IBM bidi experts.
12/08: No Progress 
17:09: AP has been in touch with  WTX and IBM experts. Support will cover 
    1) Specifying bidi string in DFDL schema,
    2) Representaion in the infoset
    3) bidi propeties to describe instance data, including applicability 
to syntax elements
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 
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.
29/07: No Progress (lower priority)
05/08: No Progress (lower priority)
12/08: No Progress (lower priority)
19/08: No Progress (lower priority)
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.
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
055
Document which properties can take an expression
12/08: AP has distributed proposed list of properties and wording
19/08: SH to review proposal
056
resolve lenghtKind=bits including fillbytes
12/08: No Progress
19/08: No Progress
057
Decide semantics and enumeration for 'parsed'  occursCountKind 
058
Should dfdl:initiatedContent be discriminating?

Closed actions:

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.
09/06: Payload should be specified using a choice rather than xs:any
17/06: SH still working on example using variables 
24/06: SH to document how property list satisfies uses cases.
01/07: SH to document how property list satisfies uses cases. PL looking 
at variable also. MB suggested modelling first separator as data for use 
case 3.
15/07: Action 042 on variables now includes examples of enevlopes and 
payloads. SH will also circulate what he has agreed with WTX team.
29/07: no progress
05/08: see action 042
12/08: see action 042
19/08: As fixOnMatch is no longer required in dfdl v1, Envelopes/payloads 
is completely covered by action 042 Variables.  Closed 



Work items:
No
Item
target version
status
003
Variables (from action 042) 
036
awaiting completion of action 042
005
Improvements on property descriptions 

not started
006
Envelopes and Payloads (from action 026)
036
awaiting completion of actions 026 and 042
007
valueCalc (from action 029) 
036
ensure all aspects documented
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)
036
ensure all behaviour documented
036
Update dfdl schema with change properties 


038
Improve length section including bit handling

not started
042
Mapping of the DFDL infoset to XDM 

not required for V1 specification
051
Revised scoping rules (from action 051)
036
awaiting completion of action 051
052
add entity for  'one or more white space characters'
036

053
name, baseFormat, selector, escapeSchemeRef, textNumberFormatRef, 
textCalendarFormatRef, binaryCalendarFormatRef attributes only
036

054
Add occureCountKind='parsed'
036

055
Make dfdl:initiatedConet discriminating
036











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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