Open Grid Forum: Data Format Description Language Working Group

Weekly Working Group Conference Call
13:00 GMT, 12 November 2008


Attendees

Steve Hanson (IBM)
Mike Beckerle(Oco)
Alan Powell (IBM)

1. Schema Component Designator specification changes.

DFDL currently uses as part of the infoset to point to schema item associated with infoset item. Sandy Gao had alerted us to some changes in the SCD spec. MB reviewed these changes and concluded that the changes removed some limitations an so DFDL could now just reference the SCD spec without caveats.
     
2. Selectors

Discussed Suman's comment on last call's decision on selectors. Reconfirmed the decision

3. Moving to XSD 1.1 as base for DFDL

MB has done an initial review of the XSD 1.1 changes and identified some new features that might be used instead of DFDL extensions. Such as Alternative types instead of selectors and xpath instead of DFDL expression language. MB to review further.

4. Multi-level semantics.

Discussed why schema had use this style and concluded it was not necessary for DFDL as we could build on the schema work.

In passing noted the need to standard for examples in the dfdl spec for showing scoped properties

Subsequent MB email

In the DFDL spec., the problem exists of how to express the behavior of a construct in the situation where there are properties in scope surrounding the construct.
 
I believe this kind of syntax can be used in the spec. to make clear the implications of scope:
 
 Properties in scope: lengthKind="implicit"
             representation="text"
<sequence dfdl:separator=”,” dfdl:terminator=”;”
          dfdl:lengthKind="delimited">   // these are local
   <element name=”f1” type=”string” />
   <element name=”f2” type=”string” />
</sequence>
 
I would suggest the above syntax for the DFDL spec as a way to discuss property semantics. The only way properties can get in scope is by way of an enclosing complexType definition; but using that syntax explicitly begs the question of whether one means true lexical enclosure, can there be other enclosing complexTypes also, etc. The above style eliminates these issues.

5. Action Items/ Work Items.

Went through actions. Updated below

6. AOB
Next call 18 November

Meeting closed, 13:10 GMT


Actions raised at this meeting
No
Action
024
String XML type
025
Escape schemes
026
SH: Envelopes and Payloads
027
Property precedence tables
028
Variable markup
029
 valueCalc (output length calculation)

Current Actions:
No
Action
003
AP: Update spec from WTX document
13/8:  All resolved issues have been added to spec. Remaining unresolved items need discussion
10/9: Alan will pull out the remaining unresolved items and circulate for discussion next week
17/9: Doc distributed and partially discussed
15/10: All updateds complete except minlength
22/10: No update
12/11: Updates have been sent to wtx to review. Will chase up for comments
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
018
AP: Agree padding to minimum length
15/10: Needs documenting
22/10: No update
020
SH: Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy
22/10: No progress
023
MB: Review Schema 1.1

Closed actions:
004
MB: Mike will also author a new section in response to comments from Sandy Gao and Suman Kalia, explicitly connecting syntax with DFDL semantics
16/7: no progress
10/9: Mike not convinced this is necessary. Steve to talk to Sandy to see if it is needed for any IBM implementation that extends the existing XML parsing framework
15/10: SH to talk to Sandy
22/10: SH needs reminding of what this issue is about
12/11: Decided not needed. Closed
007
AP: enum + expression wording
13/8: no progress
10/9: No update
17/9: No update
22/10: No update
12/11: converted to work item
014
SH: Use cases for lengthKind pattern on binary fields.
10/9: Not done
17/9: No update
22/10: SH not sure he can provide a concrete use case
12/11: SH had identified need for pattern of complex structures with binary comtent which already included. Decided to allow patterns on simple binary fields for symetry. Closed
016
AP: Add hidden changes to spec
22/10: No update
12/11:converted to work item
017
All: Review EndOfData changes
22/10: SH response mailed to Mike
5/11: Discussed on call and design agreed
12/11: converted to work item
019
AP: Document defineTextNumber etc
22/10: No update
12/11:converted to work item
021
AP: Document textNumberRepresenation and binaryNumberRepresentation
22/10: No update
12/11:converted to work item
022
SH: Talk to Sandy Gao to assess use of schema 1.1
22/10: Mail sent to Sandy
12/11: track as action 023

033 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)
004
Selectors (Suman/Alan) - Apr 30, 2008
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) - *complete but 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 *
013
(from F2F) New scoping rules
014
(from F2F) Occurs, OccurSeparator changes
015
(from F2F) choices and Output (Mike)
016
(from F2F) xpath forward references (Alan) *complete*
017
(IBM WTX review) Minor agreed updates (Alan) *complete*
018
(IBM WTX review) Review generateNewLine (Alan) *complete*
020
(IBM WTX review) Special value for zero seen eg 'zero'. (Steve)
021
(IBM WTX review) 'EndOfData' changes (Alan)
022
(IBM WTX review) Unresolvable choices - infoset changes *complete*
023
(IBM WTX review) separatorKind=’prefix’ ‘infix’ or ‘postfix’ (Alan)
024
(IBM WTX review)  StopValue clarification (Alan)  
025
Augmented infoset and unparsing (Alan)  
026
Hidden changes
027
Add decimal supp to main spec
028
Remove extended floats
029
AP: enum + expression wording
030
AP: Add hidden changes to spec
031
All: Document EndOfData changes
032
AP: Document defineTextNumber etc
032
AP: Document textNumberRepresenation and binaryNumberRepresentation



Alan Powell

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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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