[DFDL-WG] Agenda for OGF WG call 20 May 2009

Wed May 20 05:55:15 CDT 2009

Note: the call is scheduled for 2 hours

Agenda: 

1. Go through actions. 

2.  Codepage for text items in infoset.
  It is proposed that text values in the infoset should be ISO10646.

3. Annotations on Top Level element

4 .Scoping of elements and Types
MB has pointed out a problem with the current scoping rules and proposed 
that propoeties on an element should override those on its type.

5. Scoping rules for assert/discriminator and other annotations 

6. Need for the equivalent of WTX Restart
Restart indicates where in the schema to restart parsing when unable to 
correctly parse content

7. Built-in Specifications
Spec Section 23 Built-in Specifications
TBD: this section gives the names, import URLs for, rep-property 
definition sets, property definitions, etc. for the built-in named format 
definitions

8. AOB 

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. 
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 
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 to issues. 
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 
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 
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 
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 
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 
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. 
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 
039
SKK: Approach for creating Schema-For-DFDL xsds. 
22/04: Resolve issue around multiple declarations needed for DFDL 
properties, perhaps using MB's meta approach 
29/04: Don't like qualified attributes in long form. SKK to check there 
are no code gen implications, eg EMF. 
06/05: SKK will send update by Friday 
040
SH: LengthKind on complex objects.   
29/04: All send comment before next call 
06/05: See minutes. Agreed to remove lengthKind from sequence and choice. 
041
AP: UnorderedInitiated 
29/04: All: Review for next call 
06/05: See minutes: Agreed to generalize to all sequences 
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 
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? 
044
13/05:  Bidi

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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