Please see below for a proposal to make an additional set of DFDL features optional.  The goal is to make it considerably easier to create a minimal conforming DFDL processor for binary data.

Regards

Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh@uk.ibm.com
tel:+44-1962-815848
----- Forwarded by Steve Hanson/UK/IBM on 11/05/2012 12:50 -----

Feature	Detection
Text representation for types other than String	dfdl:representation="text" for Number, Calendar or Boolean types
Delimiters	dfdl:separator <> "" or dfdl:initiator <> "" or dfdl:terminator <> "" or dfdl:lengthKind="delimited"
BCD calendars	dfdl:binaryCalendarRep="bcd"
Multiple schemas	xs:include or xs:import in xsd
Named Formats	dfdl:defineFormat or dfdl:ref
Choices	xs:choice in xsd **
Arrays where size not known in advance	dfdl:occursCountKind 'implicit', 'parsed', 'stopValue' **
Advanced expressions	Advanced features of the DFDL expression language (tbd)

** Including one of these features mean that speculative parsing is needed.

Remaining questions:

1) What about lengthKind 'endOfParent' ?
2) Is leaving out choices too restrictive?
3) Expression language subset

The result is that a minimal conformant DFDL implementation just needs to support the following annotations and properties, and does not need speculative parsing.

dfdl:element
dfdl:sequence
dfdl:format

byteOrder
encoding
utf16width
alignment
alignmentUnits (bytes)
fillByte
leadingSkip
trailingSkip
lengthKind (explicit, implicit)
length
lengthUnits (bytes, characters)
representation (binary)
textPadKind
textTrimKind
textStringJustification
textStringPadCharacter
truncateSpecifiedLengthString
decimalSigned
binaryNumberRep
binaryVirtualDecimalPoint
binaryFloatRep (ieee)
binaryBooleanTrueRep
binaryBooleanFalseRep
binaryCalendarRep (binarySeconds, binaryMilliseconds)
binaryCalendarEpoch
sequenceKind (ordered)
occursCountKind (fixed, expression)
occursCount

Regards

Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh@uk.ibm.com
tel:+44-1962-815848


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