Open Grid Forum: Data Format Description Language Working Group

OGF DFDL Working Group Call, April-15-2009

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

Apologies

1. Escape Schemes
Alan has mailed latest refinement (V2) just before the call. MB sent comments
Agreed to drop escapeKind='escapeBlock2' as it was quite resctrictive and was primarily intended for XML style escaping which should be covered by representation='XML'.
We got bogged down in individual use cases so AP agreed to document a set of use cases

2. 'Floating' definitions
SH had sent out an example of need for floating definitions.
The NTE segment in older X12 formats can appear multiple times anywhere within a transaction.
This could be modelled in dfdl using
- an array of choices which has all the possible fields as choices. This would mean that the fields other than the NTE segment could appear in any order so the document could not be validated using just the schema.
- Inserting an optional NTE segment between every other segment. Such a schema would violate UPA rules if any other segments were optional.
SH will investigate further to find out if this is used in versions of X12 that should be supported by DFDL v1.


3. Recursive use of DFDL for variable markup

SH  has sent a use case which WTX solved using 'variable markup'.

The use case is from EDI.  EDI transactions consist of an initial header segment which defines, among other things, the separator that is used by the data segments that follow. The problem is that EDI transactions may be processed in their entirety, or individual data segments may be processed without the header segment.  For the former case, DFDL supports this fine, using an XPath expression to locate the separator, which is defined as an element, the simple type of which enumerates the allowable values, enabling validation. But for the latter case, the XPath expression won't resolve, as there is no header. An explicit dfdl:separator property could be used instead, being a space separated list of all the allowable values - but that then duplicates the separator element enums, leaving a maintenance problem.

To be discussed on next call.

4. AOB
Issues to be discussed
- Suman has identified a identified that the short and long form properties require all dfdl properties to be defined at least twice in the schema for DFDL.

- The scoping rules for annotations other than dfdl:format are not specified and need to be clarified.

Actions updated below.

Next call 22 April 14:00 UK

Meeting closed, 15:15

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
020
SH: Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy
22/10: No progress
10/12: added how to decide to overpunch and sign position
11/02: proposal largely agreed. SH to make minor changes
18/02: AP to document unsigned type behaviour
25/02: no progress
08/04: Not discussed
023
MB: Review Schema 1.1
29/1: AP and SH to talk to Sandy Gao
04/02 Call arranged for Friday
11/02: Call took place. Identified useful changes. Consolidate with previous list.
04/03: decided to stay on Schema 1.0.
08/04: Not discussed
024
String XML type
08/04: Not discussed
025
Escape schemes
21/1: discussed requirements
04/02: AP/SH to describe behaviour for known length text fields. Need to discuss if comment escapes should be supported.
11/02 new draft distributed:
18/02: SH up document concerns
25/02: SH and AP have refined proposal ready for approval.
04/03: SH and AP have further refined proposal.
11/03: discussed. suggested a simplified proposal be evaluated.
18/03: SH and AP had further discussions on simplified proposal
08/04: See minutes, review in detail for next call
15/04: See minutes, review for next call
026
SH: Envelopes and Payloads
08/04: Not discussed explicity, but recursive use of DFDL is tied up with this
027
Property precedence tables
08/04: Not discussed
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: Used case was distributed and will be discussed on next call.
029
valueCalc (output length calculation)
08/04: Not discussed
032
DG: Investigate compatibility between DFDL infoset and XDM
08/04: No update
033
AP/TK: Assert/Discriminator semantics. AP to document. TK to check uses of discriminator besides choice.
08/04: In progress within IBM
034
AP: Remove redundant properties, correct old examples
08/04: No update
035
AP: Add validation ranges to spec, update specialized annotations in spec.
08/04: Raised. For draft 0.34
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

Closed actions:

Work items:
No
Item
001
String XML type (Ian P) - Apr 30, 2008
002
Escape schemes (Ian P) - Apr 30, 2008
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
010
(from draft 32) Assertions, discriminators and choice, including discussion of timing option (Suman) - Mar 31, 2008 * in progress *
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 *
025
Augmented infoset and unparsing (Alan)   added but needs work
026  Remove duration




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