[DFDL-WG] Minutes for OGF DFDL Working Group Call, May 26-2010

Thu May 27 05:58:01 CDT 2010

Open Grid Forum: Data Format Description Language Working Group

OGF DFDL Working Group Call, May 26-2010

Attendees
Steve Hanson (IBM) 
Alan Powell (IBM) 
Suman Kalia (IBM)
Stephanie Fetzer (IBM)
Mike Beckerle (Oco)

Apologies
Tim Kimber(IBM) 

1 Nils, defaults
The whole call was spent discussing the proposed changes to the nils and 
defaults sections including Stephanie's comments.

Definition of 'has default value'
Minor clarifications to simple element. For complex element it is an 
'effective' default value.
Clarified default for choices.

Definition:'required'
Clarified that required is in terms of the infoset.

Didn't like the used of 'index' in the definition of variable occurrence 
elements.

Agreed that ASSERTs do not make an element required. Stephanie to consider 
examples to confirm this is correct.

Suggest introducing 'required context' to explain defaulting in complex 
elements.

Discussed the restriction that choice branches may noy have minOccurs = 0 
and whether that was sufficient. The was introduced to prevent the empty 
string being implicitly a valid choice but Mike pointed out that making 
all the children of a choice branch optional has the same effect. Not 
resolved.

Discussed whether anonymous sequences and choices were required. Concluded 
that it wasn't a valid question when required is in terms of the infoset. 
Thus if anonymous sequences and choices have an initiator or terminator 
they will always be present in the data stream. If they need to be 
optional then the seq/choice has to be wrapped in an element.

Suggest removing the definition of success.

Largely agreed on the definition of missing.

2  OGF 29   
Chicago, June 20-22 
Not discussed

3 Current Actions 
Not discussed

4 Trailing alignment with lengthKind delimited or endOfParent 
Is it sensible to allow Trailing skip bytes with LK delimited 

The grammar says that trailing alignment is applied before the separator 

So the parser must search for the separator then remove the trailing bytes 
from the value and length. 

@Data1   *Data2*#       -  Test1 value=Data1 length=5

@Data1*Data2*#          -  Test1 value=Da length=2   (do we require that 
the trailing data must be the fillByte?) 

But bear in mind that the grammar effectively says: 

        RightFraming = Terminator TrailingSkipBytes 

So the combination of dfdl:lengthKind="delimited" & dfdl:trailingSkipBytes 
would work when the delimiter is a terminator. 
Not discussed

Meeting closed, 16:30

Next call  Wednesday 02 June  2010  15:00 UK  (10:00 ET)

Next action: 092
Actions raised at this meeting

No
Action 

Current Actions:
No
Action 
066
Investigate format for defining test cases
25/11:IBM to see if it is possible to publish its test case format.
04/12: no update
...
17/02: IBM is willing in principle to publish the test case format and 
some of the test cases. May need some time to build a 'compliance suite'
24/03: No progress
03/03: Discussions have been taking place on the subset of tests that will 
be provided.
10/03: work is progressing
17/03: work is progressing
31/03: work is progressing
14/04: And XML test case format has been defined and is being tested.
21/04. Schema for TDML defined. Need to define how this and the test cases 
will be made public
05/05: Work still progressing
12/05: Work still progressing
084
Check behaviour of dfdl:inputValueCalc and outputValueCalc.
14/04: no prorgess
21/04: no progress
05/05: no progress
26/05: Alan has looked at the precedence tables and the look OK. Suggest 
closing.
085
ALL: publicize Public comments phase to ensure a good review..
14/04: see minutes
21/04: Press release, OMG and other standards bodies.
05/05: Alan and Steve H have contacted other standards bodies. Will ask 
them to add comments on spec
15/05: still no public comments
086
AP: Nils and Defaults during unparsing - update table
31/03: TK to documetn use cases for parsing
14/04: Investigate new property to control empty string behaviour.
21/04: After investigation a new property is not required. New rules 
developed and tables updated.
Need examples of complexTypes to confirm tables apply. 
Review Nils, defaulting spec section.
05/05: Discussed defaulting complex elements. Tables updated but need to 
add terminator.
SH; to confirm WMD behaviour when infoset item has no value on unparsing
Need to describe defaulting choices.
15/05: More discussion. Alan updating sections
26/05: Discussed draft updates. Stephanie to confirm asserts do not make 
an element required. 
Alan will update draft..  All: review rest of draft.
088
define semantics of choiceKind 'fixedLength' 
31/03: TK to provide definition of calculable length.
Investigate  PL/I varchars and Cobol occurs dependingon.
14/04Tim had distributed a document starting the definition of calculable 
length for the longest choice member.
Alan had done some investigation of COBOL occurs depending on and when 
used in the working section of a program then the maximum storage was 
reserved but when used in the linkage section the dependent number was 
uses. We need to understand how the WMB COBOL importer deals with ODO.
21/04: Need to define 'calculable length' and WMB importer ODO behaviour.
05/05: TK: Still need definition of calculable length.
SKK: WMB COBOL imported behaviour with ODO
15/05: Suman sent an expmle of an imported Cobol ODo which suggested that 
the maximum space was reserved. He will extend the example.
091
The IBM team had questioned whether timezones should be just UTC+/- offset 
or should GMT and other short time zones be allowed. Alan to investigate
15/05: Alan to talk to Ruth.
26/05: Ruth confirmed that it was only the offset from UTC or GMT. For 
DFDL purposes thates are the same. Suggest closing.

Closed actions
No
Action 

Work items:
No
Item
target version
status
005
Improvements on property descriptions 

not started
012
Reordering the properties discussion: move representation earlier, improve 
flow of topics 

not started 
036
Update dfdl schema with change properties 
ongoing

042
Mapping of the DFDL infoset to XDM 
none
not required for V1 specification
070
Write DFDL primer 

071
Write test cases.

083
Implement RFC2116

097
Remove functions that returns duration

 098
 occursCountKind="expression" is parsing only

099
nilValue and OccuresStopValue cannot have an expression.
On unparsing only outputValueCalc can have a forward reference.

100
Need to state in 4.1.2 Infoset that value is optional.

101
When dfdl:textNumberRep is ?zoned? only the pattern for positive numbers 
is used. Only the following pattern characters may be used: 

  '+' MUST BE present at the beginning or end of the pattern to indicate 
whether the leading or trailing digit carries the overpunched sign, if the 
logical type is signed 
  '+' MAY BE present at the beginning or end of the pattern to indicate 
whether the leading or trailing digit carries the overpunched sign, if the 
logical type is unsigned 
  'V' MAY BE used  to indicate the location of an implied decimal point 
  '0' indicates the number of required digits (including overpunched). 
 '#' indicates the number optional digits.

102
Also  textNumberPolicy implies it applies to zoned, but doesn't state what 
zoned behaviour it covers. I think it should be consistent with 
binaryNumberCheckPolicy for packed, and control whether positive punched 
data is accepted or rejected when parsing an unsigned type, and whether 
unpunched data is accepted or rejected when parsing a signed type.

103
- textStandardBase 
- textStandardGroupSeparator 
- textStandardExponentCharacter 
- textStandardInfinityRep 
- textStandardNanRep 
- textStandardZeroRep 
- textZonedSignStyle 

104
4 Unsigned decimal 
Proposed solution: 
- Allow xs:nonNegativeInteger which enables unsigned unbounded integers to 
be modelled.  The problem to solve is then just for xs:decimal. 
- Call the new property dfdl:decimalSigned. It only applies to xs:decimal 
or user defined restrictions thereof.  It applies to all physical 
decimals, as its name implies (not just zoned or packed). 

Regards

Alan Powell

Development - MQSeries, Message Broker, ESB
IBM Software Group, Application and Integration Middleware Software
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