[DFDL-WG] proposed clarification/narrowing - delimited binary data should decimal

[Steve Hanson]

Mike

The correct title of this proposal is "proposed relaxation - delimited 
binary data should be packed or BCD or BLOB"

Section 12.3.8 states what binary reps can be used with lengthKind 
'delimited'.  It explicitly lists just 'packed' and 'bcd'. Therefore 
binary numbers with binaryNumberRep 'binary', binary calendars with 
binaryCalendarRep 'binarySeconds' and 'binaryMilliseconds',  binary floats 
and doubles, binary booleans and xs:hexBinary are disallowed today. 

The binary calendar reps are always treated with fixed length of 4 and 8 
respectively, so no point in making them variable length. 
All binary floats have length 4 and all binary doubles have length 8 so no 
point in making them variable length.

I am ok with being conservative and continuing to disallow binaryNumberRep 
'binary'. As you say we can open this up in future.
Same for  binary booleans.

I agree that xs:hexBinary should be allowed to have lengthKind 
'delimited'. It will be too restrictive to only allow BLOB data to have a 
specified length, or to be bounded by parent. This is shown by IBM 4690 
point-of-sale data streams which contain instances of variable length 
delimited BLOBs. 

If we are in agreement then we need to take an errata on section 12 and 
particularly section 12.3.8 to allow xs:hexBinary to have lengthKind 
'delimited'.

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



From:   Mike Beckerle <mbeckerle.dfdl at gmail.com>
To:     dfdl-wg at ogf.org
Date:   14/08/2012 19:44
Subject:        [DFDL-WG] proposed clarification/narrowing - delimited 
binary data     should be decimal
Sent by:        dfdl-wg-bounces at ogf.org




The spec allows lengthKind='delimited' for binary data.

For calendar types, it allows only 'bcd' and 'packed' binaryCalendarRep.

There is no such restriction for integer types, so those can also be 
'binary' aka twos-complement.

We should be consistent. Either we allow binaryCalendarRep='binary', or we 
disallow binaryNumberRep='binary'.

I propose we disallow binaryNumberRep='binary'. Rationale: conservative 
choice. We could open it up later if there was reason to do so, but we 
can't easily restrict it later if we find it problematic.

This leaves only hexBinary as the exception. Elements of type hexBinary 
can have lengthKind='delimited', and the schema author simply has to 
understand what byte pattern is usable as a delimiter.

-- 
Mike Beckerle | OGF DFDL WG Co-Chair 
Tel:  781-330-0412
--
  dfdl-wg mailing list
  dfdl-wg at 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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.ogf.org/pipermail/dfdl-wg/attachments/20120815/5f73ebcf/attachment.html>