[DFDL-WG] Action 174: Making DFDL implementations easier

[Tim Kimber]

1) I would make endOfParent an optional feature - there are not many 
formats that require it.

3) There are many formats that do not require the expression language - it 
is only required when a property value or an assert/discriminator needs to 
query already-parsed data. On that basis, I think the entire expression 
language feature should be optional.

regards,

Tim Kimber, Common Transformation Team,
Hursley, UK
Internet:  kimbert at uk.ibm.com
Tel. 01962-816742 
Internal tel. 246742




From:   Steve Hanson/UK/IBM at IBMGB
To:     dfdl-wg at ogf.org
Date:   25/05/2012 00:08
Subject:        [DFDL-WG] Action 174: Making DFDL implementations easier
Sent by:        dfdl-wg-bounces at ogf.org



Agreed on list, just need to answer questions 1) and 3) below. 

Regards

Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848 
----- Forwarded by Steve Hanson/UK/IBM on 23/05/2012 18:21 ----- 

From:        Steve Hanson/UK/IBM 
To:        dfdl-wg at ogf.org 
Date:        15/05/2012 09:55 
Subject:        Making DFDL implementations easier 


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 at 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 at uk.ibm.com
tel:+44-1962-815848 


Unless stated otherwise above:
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741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU

Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
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