[DFDL-WG] Spec correction ? - Section 9.3.2.1 - second list missing "empty" representation

[Mike Beckerle]

Ah,

So 9.3.2 talks only about the content region being zero length. I get that
now. I was not reading the word "content" specifically enough.

I also get that the second numbered list under 9.3.2.1 can't discuss empty
representation, because the content region has been identified as non-zero
length.

I think there are still some problems here.

In 9.3.2, I believe it's point about delimited lengthKind is problematic.
You don't even know whether you are scanning for a terminator or not unless
you entertain whether nillable, empty/defaultable, or normal - because of
nilValueDelimiterPolicy, emptyValueDelimiterPolicy, and
initiator/terminator. It's not correct to just look for a separator (if
there even is one) here. I think if the lengthKind is 'delimited', then you
must consider the nil representation with framing, empty representation
with framing, and normal representation with framing (for string and
hexBinary), in order to even find, positively, the content region in order
to say that it is zero length. This is particularly true if dfdl:initiator
and dfdl:terminator are the same string.

Delimiter "immediately found" isn't even a valid concept for a non-nillable
complexType, as one must recurse into the type. So I think we need to be
clear that a non-nillable complex type is simply not ever considered
"trivially zero length".

I think the clearest thing to fix 9.3.2 is for 'delimited' is to provide
the case analysis:

'delimited' => if nillable, is content zero length after initiator and
before terminator framing as required by nilValueDelimiterPolicy
                     if simpleType - is content zero length after initiator
and before terminator framing framing as required by
emptyValueDelimiterPolicy
                     if simpleType xs:string or xs:hexBinary - is content
zero length after initiator and before terminator framing (if such framing
is defined.)
                     otherwise - not trivially zero length.

I think 9.3.2.1 needs to make the implied point about being about the
content only, and then about having the corresponding required framing
explicit e.g., the first sentence could change to:

     "If the *content* is length zero as described above, the
representation is then established by checking, in order for:"


After the numbered lists, a concluding sentence can say "In all cases above
establishing a representation includes that it must be surrounded by its
corresponding initiator/terminator if required for that representation's
framing based on dfdl:nilValueDelimiterPolicy,
dfdl:emptyValueDelimiterPolicy, dfdl:initiator, and dfdl:terminator."


9.3.2.2 Similarly needs to specify that "Establishing nil representation
includes that it must be surrounded by its corresponding
initiator/terminator if required based on dfdl:nilValueDelimiterPolicy,
dfdl:initiator, and dfdl:terminator."




Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are
subject to the OGF Intellectual Property Policy
<http://www.ogf.org/About/abt_policies.php>


On Wed, Aug 1, 2018 at 7:45 AM, Steve Hanson <smh at uk.ibm.com> wrote:

> Mike
>
> 9.3.2.1
>
> First numbered list. It's implicit, as is the non-reference to
> nilValueDelimiterPolicy for nil rep.
> Second numbered list. Should not mention empty - can't be empty as not
> zero length.
>
> Don't understand what you mean by empty rep is non-zero length. We are
> talking about the content region only here.
>
> Regards
>
> Steve Hanson
>
> IBM Hybrid Integration, Hursley, UK
> Architect, *IBM DFDL*
> <http://www.ibm.com/developerworks/library/se-dfdl/index.html>
> Co-Chair, *OGF DFDL Working Group* <http://www.ogf.org/dfdl/>
> *smh at uk.ibm.com* <smh at uk.ibm.com>
> tel:+44-1962-815848
> mob:+44-7717-378890
> Note: I work Tuesday to Friday
>
>
>
> From:        Mike Beckerle <mbeckerle.dfdl at gmail.com>
> To:        dfdl-wg at ogf.org
> Date:        17/07/2018 15:11
> Subject:        [DFDL-WG] Spec correction ? - Section 9.3.2.1 - second
> list missing        "empty" representation
> Sent by:        "dfdl-wg" <dfdl-wg-bounces at ogf.org>
> ------------------------------
>
>
>
>
> In section 9.3.2.1, there are two numbered lists.
>
> The first numbered list should qualify its mention of "empty
> representation" with "(when the emptyValueDelimiterPolicy and initiator and
> terminator policies are defined such that zero-length is allowed as the
> empty representation.)"
>
> The second numbered list should mention nil (literal), nil (logical),
> empty, and normal representations.
>
> It is missing discussion of non-zero-length "empty" representations (due
> to emptyValueDelimiterPolicy not none, and initiator and terminator defined
> such that the empty representation is non-zero length).
>
> Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
> *www.tresys.com* <http://www.tresys.com>
> Please note: Contributions to the DFDL Workgroup's email discussions are
> subject to the *OGF Intellectual Property Policy*
> <http://www.ogf.org/About/abt_policies.php>
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