On Fri, May 25, 2012 at 7:59 AM, Steve Hanson <smh@uk.ibm.com> wrote:

Tim

I tend to agree with endOfParent as optional.

Expression language was kept in the core to handle occursCountKind 'expression' which is also in the core. The examples of binary data we have seen from NSA and ESA both have occurs counts in the data, in the same way as COBOL does. When you have untagged binary data, it's typically the way to provide an array size. It was felt that dropping this from the core did left us with too little capability.

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

From: Tim Kimber/UK/IBM
To: Steve Hanson/UK/IBM@IBMGB
Cc: dfdl-wg@ogf.org, dfdl-wg-bounces@ogf.org
Date: 25/05/2012 10:07
Subject: Re: [DFDL-WG] Action 174: Making DFDL implementations easier

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@uk.ibm.com
Tel. 01962-816742
Internal tel. 246742

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

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

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
-- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg

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

--
dfdl-wg mailing list
dfdl-wg@ogf.org
https://www.ogf.org/mailman/listinfo/dfdl-wg

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)