[DFDL-WG] Agenda for OGF WG call 10 June 2009

Alan Powell alan_powell at uk.ibm.com
Wed Jun 10 05:46:33 CDT 2009


1. Go through actions.

2. Implementation concerns
The implementation of a dfdl editor, validator and parser have highlighted 
some some concern. SH to send email

3. AOB 

Current Actions:
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 
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)
SH: Envelopes and Payloads
08/04: Not discussed explicity, but recursive use of DFDL is tied up with 
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
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
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
09/06: SH proposal discussed. ICU questions to be researched
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.
09/06: SH/AP proposal discussed and MB to document

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)
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.
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
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
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 
20/05: SH No progress
27/05: No Progress
03/06: No Progress
09/06: SH proposed staying with XML built-in types. Closed
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
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
20/05 AP: Scoping for non-format annotations
27/05: Discussed briefly. AP to distribute
03/06: Proposal discussed briefly. Will be updated.
09/06: Doc emailed. Awaiting outcome of variable to define/setvariable 
20/05: AP investigate Restart
27/05: Suggest RESTART is not part of the scope for DFDL.
03/06: not discussed
09/06: Closed
20/05 AP Built-in specification description and schemas
03/06: not discussed
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

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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