Open Grid Forum: Data Format Description Language Working Group

OGF DFDL Working Group Call, March-18-2009


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

Apologies
Mike Beckerle(Oco)


1.  Specialized Annotations

The whole call was taken up discussing the "dfdl:sequence and other specialized annotations" proposal emailed by SH. In summary proposes
- the use of specialized annotations on each schema object. eg dfdl:sequence
- a separate set of scoped properties for each specialization.
<xs:complexType name="myType">
   <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”>
     <dfdl:complexType>
       <dfdl:sequence lengthKind="implicit" ... />
       <dfdl:element lengthKind="delimited" ... />
     </dfdl:complexType>
   </xs:appinfo></xs:annotation>

There was general agreement with the proposal but a lot of discussion about the two issues that SH identified.

a. The meaning of short form annotations on complex type.
<xs:complexType name="myType" dfdl:lengthKind="implicit" ... >

It is not clear which specialized annotation scope the short form properties on complex type should apply to.
There was a lot of discussion between 1) disallowing short form annotation on complex type and 2) applying them to all specialized scopes.
Disallowing short form is simple but makes complex type different, forces long form which is much more verbose, means common properties, eg encoding, to be specified the same on multiple specialized annotations. This is a particular problem for element and simple type.
However applying short form to all specialization introduces a new level of inheritance  and consequent complexity.

b. You are forced to set common properties in multiple places in defineFormat.
<xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”>
 <dfdl:defineFormat>
   <dfdl:sequence encoding="UTF-8" ... />
   <dfdl:element encoding="UTF-8" ... />
   <dfdl:simpleType encoding="UTF-8" ... />
   <dfdl:choice encoding="UTF-8" ... />
   <dfdl:any encoding="UTF-8" ... />
 </dfdl:defineFormat>
</xs:appinfo></xs:annotation>

Possible solution is to wrap with dfdl:format

<xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”>
 <dfdl:defineFormat>
   <dfdl:format encoding="UTF-8" ... >
   <dfdl:sequence ... />
   <dfdl:element ... />
   <dfdl:simpleType ... />
   <dfdl:choice ... />
   <dfdl:any ... />
 </dfdl:defineFormat>
</xs:appinfo></xs:annotation>

The consensus was that there should be a way to provide common properties so this solution was preferred
and you could use the same for complex type

    <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”>
     <dfdl:complexType>
       <dfdl:format encoding="UTF-8" ... >
          <dfdl:sequence ... />
          <dfdl:element ... />
          <dfdl:simpleType ... />
          <dfdl:choice ... />
          <dfdl:any ... />
      </dfdl:complexType>
   </xs:appinfo></xs:annotation>

It was agreed that this was the preferred solution.

During the discussion SK asked what was the precedence of short and long-form properties on the same object. AP subsequently sent SK section 10.3 which states that long-form have precedence over short-form.

2. AOB
To be discussed
-  Escape Schemes
-  Validation ranges and exclusion lists  
- Consuming extraneous data after schema has be used.
-  'Floating' definitions
-  Actions

Next call 25 March 14:00 UK

Meeting closed, 15:00 GMT


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.
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
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.
024
String XML type
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
026
SH: Envelopes and Payloads
027
Property precedence tables
028
Variable markup
029
 valueCalc (output length calculation)
031
DG: Review dfdl v033
11/02:  Initial comments received
18/02: Will include work items 5 and 12.
11/03: complete
032
DG: Investigate compatibility between DFDL infoset and XDM
033
04/03: Assert/Discriminator semantics. AP to document. TK to check uses of discriminator besides choice.
034
04/03: AP remove redundant properties

Closed actions:

034 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

complete - specification updated



Alan Powell

MP 211, IBM UK Labs, Hursley,  Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM     email: alan_powell@uk.ibm.com  
Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898



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