[DFDL-WG] proposed clarification/narrowing - no twos-complement decimal, integer or nonNegativeInteger

[Mike Beckerle]

Do we have a section where this goes?

There are lots of implied implementation limits.

Maximum string length?
Maximum hexbinary length?
Maximum number of packed digits in various numbers.

Maximum length of a delimiter?
Maximum length of a fixed attribute?
Maximum length of a pattern regex expression?
Maximum length of a regular expression?

There's also limits on buffering of data for unparsing, etc.

There's also limits on lookahead/speculation. I.e., how far an
implementation is willing to speculate forward.

etc.

For some types these are clear: e.g., binary xs:int is 32 bits max.

Do we need a numbered section on implementation specific limits.

On Tue, Sep 4, 2012 at 12:30 PM, Steve Hanson <smh at uk.ibm.com> wrote:

> Agreed on DFDL WG call 4th Sept to continue to support twos-complement
> decimal, integer or nonNegativeInteger, but to make the maximum
> implementation defined.
>
> Regards
>
> Steve Hanson
> Architect, Data Format Description Language (DFDL)
> Co-Chair, *OGF DFDL Working Group* <http://www.ogf.org/dfdl/>
> IBM SWG, Hursley, UK*
> **smh at uk.ibm.com* <smh at uk.ibm.com>
> tel:+44-1962-815848
>
>
>
> From:        Steve Hanson/UK/IBM
> To:        Mike Beckerle <mbeckerle.dfdl at gmail.com>
> Cc:        dfdl-wg at ogf.org, dfdl-wg-bounces at ogf.org
> Date:        15/08/2012 13:10
> Subject:        Re: [DFDL-WG] proposed clarification/narrowing - no
> twos-complement decimal, integer or nonNegativeInteger
> ------------------------------
>
>
> Mike
>
> Having thought about this since our call yesterday, I am uncomfortable
> with the proposed narrowing. It means DFDL can not be guaranteed to handle
> the two's complement result of Java BigInteger.toByteArray().  I don't have
> a concrete use case of two's complement data > 8 bytes but I am sure that
> someone in the scientific community will need it at some point. Hence why
> it is allowed in the spec today.
>
> If we do allow it, then we have to decide what happens during unparsing
> and lengthKind is 'prefixed'.   The equivalent of Table 16 for lengthKind
> 'pattern' is needed for lengthKind 'prefixed', as we discussed.  That would
> imply that the unparsing behaviour would be 'Minimum number of bytes to
> represent significant digits and sign'.  In other words, a two's complement
> binary integer is created that is just long enough to represent the infoset
> value.
>
> Regards
>
> Steve Hanson
> Architect, Data Format Description Language (DFDL)
> Co-Chair, *OGF DFDL Working Group* <http://www.ogf.org/dfdl/>
> IBM SWG, Hursley, UK*
> **smh at uk.ibm.com* <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 19:33
> Subject:        [DFDL-WG] proposed clarification/narrowing - no
> twos-complement decimal, integer or nonNegativeInteger
> Sent by:        dfdl-wg-bounces at ogf.org
> ------------------------------
>
>
>
>
> The spec is not clear on whether decimal, integer, and nonNegativeInteger
> support representation='binary' with binaryNumberRep='binary' (aka
> twos-complement). Since these types do not have any size limit, such a
> capability allows arbitrarily large twos-complement integers, or perhaps it
> would be an implementation defined limit.
>
> I believe the right choice is that it should be disallowed. That is, only
> binaryNumberRep of 'bcd' or 'packed' should be allowed for these types.
> These types have always been about decimal-style representations to me.
>
> This keeps twos-complement only for the types long, int, short, byte and
> their unsigned counterparts.
>
> --
> Mike Beckerle | OGF DFDL WG Co-Chair
> Tel:  781-330-0412
> --
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>
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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
>
> --
>   dfdl-wg mailing list
>   dfdl-wg at ogf.org
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>



-- 
Mike Beckerle | OGF DFDL WG Co-Chair
Tel:  781-330-0412
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